2022

Mesoscale Discussion #0007


Concerning...Severe potential...Tornado Watch likely 


Valid 011737Z - 011930Z


Probability of Watch Issuance...95 percent


SUMMARY...A gradual increase in thunderstorm coverage is anticipated from northern LA, southeast AR, and central/northern MS this afternoon. Tornadoes are possible and a Tornado Watch will likely be issued to cover this threat.


DISCUSSION...Recent surface analysis reveals a broad warm sector in place from south-central AR/northern LA eastward into MS. Temperatures within this region are generally in the mid 70s with dewpoints in the mid to upper 60s. Objective analysis and modified RAP soundings show generally 500 to 1000 J/kg of MLCAPE, with the overall buoyancy currently limited by relatively warm mid-level temperatures. Visible satellite imagery shows numerous south-southwest to north-northeast oriented cloud bands, evidence of the increasing large scale forcing for ascent as well as persistent northward moisture return. Numerous showers have developed within these bands, and a few embedded updrafts have become strong enough to 35+ dBZ. Lightning has not been observed thus far, but the persistent moisture advection coupled with increasing large-scale forcing for ascent will likely result in at least a few more robust/organized updrafts. 


Kinematic fields throughout this warm sector are quite strong, with regional VAD profiles at SHV and DGX sampling 40 to 50 kt winds in the 1 to 2 km layer. Mesoanalysis estimates effective bulk shear is over 60 kt for most of the region. Surface winds are modestly veered but the strong low to mid-level flow still results in enough low-level curvature for tornadogenesis. Expectation is for a gradual increase in updraft depth/lightning activity over the next few hours. As these storms organize, a few discrete supercells are possible, with an attendant risk for tornadoes and damaging wind gusts. A Tornado Watch will eventually be needed to cover this potential threat.

Mesoscale Discussion #0054


Concerning...Severe potential...Watch possible 


Valid 091056Z - 091230Z


Probability of Watch Issuance...40 percent


SUMMARY...The threat for a tornado or two may persist for another couple of hours, and a small tornado watch could be needed.


DISCUSSION...The anchoring storm of a persistent cluster has developed more persistent/obvious supercell structure as it moves into southeast Sabine Parish in west central LA.  The storm in riding near or just north of the marine warm front which demarcates 68-70 F boundary-layer dewpoints, and the VWP from POE has shown a recent increase in 0-1 km SRH to near 300 m2/s2.  Thus, while the window of opportunity may be rather small (given somewhat weaker buoyancy and dewpoints a few degrees lower to the east), the near-storm environment appears favorable for a tornado threat for the next couple of hours.  Thus, a small tornado watch could be needed soon.


**This MCD was issued as the Sabine Parish EF2 was ongoing

Mesoscale Discussion #0120


Concerning...Severe potential...Watch likely 


Valid 031553Z - 031800Z


Probability of Watch Issuance...80 percent


SUMMARY...Storms have developed in southeastern Louisiana and will continue eastward today. Modest destabilization and strong shear will support organized storms capable of damaging winds and tornadoes. A watch is likely by early afternoon.


DISCUSSION...A line of pre-frontal thunderstorms has developed within the last 30 minutes west of Lake Pontchartrain. Other discrete storms have developed along the Mississippi/Alabama Gulf Coast and shown some rotation before weakening as they move inland. Warm/moist air continues to advect northward ahead of this activity as the surface low will steadily migrate northeastward through the Tennessee Valley today. Based on this morning's observed and model forecast soundings, it appears that temperatures will have to reach the low 70s F for storms to become surface based. At least muted surface heating south of greater mid/high-level clouds in northern Mississippi and northern Alabama should support this by early afternoon. MLCAPE of 500-1000 J/kg and 35-50 kts of effective shear (values increasing from south to north) will support organized storms. Along with damaging winds, a threat for tornadoes will exist given the strong low-level veering present in regional WSR-88D VAD profiles. Storm mode will predominantly be clusters and quasi-linear segments. Discrete storms within the warm sector would pose a greater tornado threat, but lack of stronger surface heating and low-level forcing decrease confidence in this possibility. A watch will likely be needed by early afternoon.

Mesoscale Discussion #0122


The severe weather threat for Tornado Watch 18 continues.


SUMMARY...Strong to severe storms will continue northeastward into central Alabama. Some local extension in watch area may be needed if storms maintain intensity through the afternoon.


DISCUSSION...Semi-organized linear segments continue to move eastward across southern MS/AL. An embedded supercell in the Sumter County, AL, vicinity has been the most organized storm this afternoon. A possible TDS was evident on the KDGX radar around 1:10 PM CST with this storm. Storms moving into central Alabama may reach the eastern edge of the watch prior to expiration. Buoyancy becomes more limited with northeastward extent, but local extensions in area of the watch may be needed if storms maintain intensity. Across southern MS/AL, storms have been less organized despite greater buoyancy. Showers continue to develop along a pre-frontal convergence zone as well. This activity has struggled to mature. The probability of a discrete storm ahead of the cold front remains low. With time, the stronger mid-level forcing will lift northeastward and the surface low along with it. Linear forcing along the front should keep the primary threat damaging winds, given the strong low level winds that will remain.

Mesoscale Discussion #0142


Concerning...Severe potential...Tornado Watch likely 


Valid 171605Z - 171830Z


Probability of Watch Issuance...80 percent


SUMMARY...Potential for scattered discrete supercell development appears likely to increase near and east of the Mississippi River by around Noon through 3 PM CST.  These storms will pose a risk of producing tornadoes, at least a couple of which could become strong.


DISCUSSION...Influx of highest low-level moisture content is focused in a narrow pre-frontal corridor across the lower Mississippi Valley, generally along a very strong south to southwesterly lower/mid-tropospheric jet (including speeds of 50-70+ in the 850-700 mb layer).  Through 18-21Z the core of this jet is forecast to nose across the northwestern Mississippi Delta Region through middle Tennessee, but flow in excess of 50 kt likely will continue to trail south-southwestward into Louisiana coastal areas.


Along and to the west/northwest of this jet axis, large-scale ascent has been contributing to sustained convective development, but (based on soundings and visible satellite imagery) this activity has remained rooted above above a relatively deep surface-based layer characterized by weak lapse rates near moist adiabatic. This may remain the case into midday as activity gradually spreads eastward. However, breaks in cloud cover do appear to be allowing for at least weak boundary-layer destabilization near and east of the Mississippi River vicinity, and as the area of convective development/forcing for ascent approaches this region toward 18Z, intensifying boundary-layer based thunderstorm development seems increasingly possible.


Strongest mid/upper forcing for ascent appears likely to overspread much of western Kentucky and Tennessee, where boundary-layer destabilization remains much more uncertain.  However, beneath at least weakly difluent upper flow to the south, the environment is expected to be conducive to discrete storm development, in the presence of strong deep-layer shear supportive of supercells.


Of primary concern, low-level hodographs within the destabilizing warm sector will become large and clockwise curved, characterized by modest veering of winds with height and strong to extreme speed shear.  This environment may become conducive to a few sustained and strong, fast moving low-level mesocyclones, with the potential to produce strong tornadoes.

Mesoscale Discussion #0194


Concerning...Severe potential...Tornado Watch likely 


Valid 051920Z - 052145Z


Probability of Watch Issuance...80 percent


SUMMARY...Storms are expected to gradually increase in coverage and intensity this afternoon. A few tornadoes, damaging winds, and large hail all appear possible. Watch issuance is likely in the next couple of hours.


DISCUSSION...An area of precipitation with embedded storms is ongoing early this afternoon across parts of western/central IA and vicinity. This activity is being aided by strong low-level warm and moist advection occurring with a 40-50+ kt south-southwesterly low-level jet. As pronounced ascent associated with a shortwave trough ejecting across the central Plains overspreads the warm sector across IA and northern MO, additional convection is forecast to develop over the next couple of hours. The airmass across this region is gradually destabilizing, with surface temperatures generally in the mid 50s to upper 60s, and dewpoints in the low to mid 50s. Around 500-1000 J/kg of MLCAPE may ultimately develop as modest diurnal heating through cloud breaks occurs, as mid-level temperatures are expected to rapidly cool with the approach of the shortwave trough. Deep-layer shear of 50+ kt will favor supercells with a threat for both large hail and damaging winds.


There is still some uncertainty in the coverage and intensity of severe storms later this afternoon owing to the modest instability and leading band of ongoing storms, which may hamper additional diurnal heating. Potential does exist for this leading band to strengthen as it moves across central/eastern IA while posing a threat for mainly hail and strong/gusty winds. Current expectations are for a greater severe threat to develop with supercells that should form near the NE/IA/MO border, in close proximity to the surface low over northeastern KS. This activity should have access to slightly greater instability and low-level moisture, with a better chance for these storms to become surface based and produce isolated large hail. Strong low-level wind fields and 200-300 m2/s2 of effective SRH should prove favorable for updraft rotation, and a few tornadoes appear possible with any storms that can remain at least semi-discrete. Scattered damaging winds should also occur as convection attempts to grow upscale later this afternoon/early evening while moving quickly eastward across IA and northern MO. A watch will likely be needed within the next couple of hours as the severe threat gradually increases.

Mesoscale Discussion #0195


The severe weather threat for Tornado Watch 27 continues.


SUMMARY...Ongoing severe storms should continue to track east northeast over the next several hours across IA and northern MO. Damaging wind gusts, large hail and a few tornadoes will be possible. Some upscale growth is expected as storms track farther east into central and eastern Iowa later this evening.


DISCUSSION...As of 21:45 UTC, a semi-discrete band of supercells were ongoing across far southwestern IA and northwestern MO. In the wake of early-day storms, clearing ahead of a strong surface cyclone and upper trough have allowed weak destabilization (500-1000 J/kg) of MLCAPE to propagate ahead of the cells ongoing across central IA and northern MO. These storms should continue to keep pace with the rapidly recovering warm sector posing a risk for all hazards over the next few hours.


Initial storm mode has been messy with multiple updrafts in close proximity across western IA. This is likely a result of relatively-long straight-line hodographs above weekly veered surface flow. Additional upscale growth appears likely with these storms as they track northeastward. All hazards, including damaging wind gusts, and a few tornadoes will however remain possible given strong low-level shear (0-1km srh 150-200 m2/s2) supporting small mesocyclones. 


Farther south, more discrete convection across northern MO were tracking toward southern IA. Greater residence time within the expanding warm sector and resulting stronger low-level mesocyclones may result in a locally greater risk of tornadoes over the next several hours. Upscale growth into more linear segments with a risk of damaging gusts appears possible into portions of eastern Iowa where an additional watch may be needed later this afternoon/evening.

Mesoscale Discussion #0197


The severe weather threat for Tornado Watch 27 continues.


SUMMARY...The tornado threat will be focused in parts of central and southeast Iowa this evening. This threat may extend beyond the WW 27 and an additional downstream tornado watch will likely be considered this evening.


DISCUSSION...A strong supercell continues to move through southern suburbs of Des Moines. This storm has had consistent rotational velocities in the 55-70 kt range over the past hour. Other discrete storms are moving out of north-central Missouri into south-central Iowa. At least one tornado was reported in Wayne County, IA, with this activity. These storms are moving into a similar environment and will continue to pose a threat for tornadoes over the next 1-2 hours. To the west of these discrete storms, a more broken line of convection has developed along the cold front. This activity will pose greater threats for large hail and damaging winds than tornadoes.


Farther to the north and east, earlier cloud cover and precipitation has limited destabilization. For parts of eastern Iowa and perhaps far northeastern Missouri, an additional downstream tornado watch will need to be considered this evening.

Mesoscale Discussion #0292


Concerning...Severe potential...Tornado Watch likely 


Valid 211923Z - 212130Z


Probability of Watch Issuance...95 percent


SUMMARY...Conditions are becoming more favorable for supercell thunderstorms capable of all severe hazards, including very large hail (i.e. greater than 2" in diameter) and tornadoes.


DISCUSSION...Recent mesoanalysis shows a strong (i.e. 50-55 kt at 850 mb) low-level jet throughout much of the warm sector. This mesoanalysis is verified by area 18Z soundings, with CRP and FWD sampling 55 kt and 65 kt at 850 mb, respectively. Some convective contamination may have contributed to the stronger winds at FWD, but the general expectation is for these strong winds to persist throughout the warm sector this afternoon and evening. 


At the same time, strong moisture advection is contributing to air mass destabilization. Dewpoints increases around 4 deg F have occurred over the last 3 hours throughout much of central and eastern TX, with dewpoints now ranging from the upper 60s/low 70s in the AUS/CLL vicinity to low 60s across much of the Metroplex. Recent mesoanalysis indicates MLCIN has eroded across much of central TX. This is verified by a recent special sounding from St. Edwards University in Austin, which sampled limited convective inhibition remaining. Recent 18Z sounding from Texas A&M shows a bit more convective inhibition remaining.


The improving thermodynamics, supercell wind profiles and gradually strengthening ascent all suggest the potential for discrete supercells capable of all severe hazards this afternoon, including very large hail (i.e. greater than 2" in diameter) and tornadoes. Convective interference may limit the duration of any one discrete cell, but the environmental conditions do support potentially long-lived updrafts and intense supercells, particularly over central TX/TX Hill Country. A Tornado Watch will be needed this afternoon to cover this severe potential.

Mesoscale Discussion #0295


Concerning...Tornado Watch 54...


Valid 212232Z - 220000Z


The severe weather threat for Tornado Watch 54 continues.


SUMMARY...The severe threat continues across Tornado Watch #054. Large hail, damaging gusts and tornadoes may accompany any mature storm within the watch. A corridor of greater severe potential is likely developing near Austin, TX and will progress northeast through the remainder of the afternoon.


DISCUSSION...Multiple supercells, thunderstorm clusters, and linear segments have developed across the western portions of Tornado Watch #054 over the past couple of hours, with a history of tornadoes near Jacksboro and Bowie Texas. Storms continue to develop ahead of a Pacific front/dryline just west of the I-35 corridor, and are advancing east into a buoyant airmass. These storms are also progressing toward the axis of the low-level jet, where greater moisture and low-level shear exist (per 22z mesoanalysis). 20Z RAP forecast soundings (valid for 22-00Z) show large, curved hodographs downshear of the ongoing storms). As such, tornado potential is expected to increase through the remainder of the afternoon into the evening hours. 


Of particular concern are the supercells along a line from Burnet to Guadalupe Counties, which are tracking in an thermodynamic environment characterized by 2000+ J/kg MLCAPE. Given the storm mode and aforementioned buoyancy/shear, a heightened tornado threat may develop. Any supercell that becomes dominant/discrete (relatively pristine inflow) will have the greatest risk for producing strong tornadoes, and a long-lived, long-tracked tornado cannot be completely ruled out.

Mesoscale Discussion #0296


Concerning...Severe potential...Watch likely 


Valid 220003Z - 220100Z


Probability of Watch Issuance...95 percent


SUMMARY...Tornado threat will increase downstream of ww54 in the next few hours. New tornado watch will be warranted by 01z.


DISCUSSION...Strong upper trough is ejecting across TX this evening as 500mb speed max translates through the base of the short wave toward southeast OK where speeds should increase in excess of 100kt by 06z. This feature will focus an intense LLJ across northeast TX/eastern OK with an eastward shift into AR by late evening. Air mass is expected to recover across northeast TX into the Arklatex region as the surface low tracks deeper into OK.


Several long-lived supercells with confirmed tornadoes are ongoing across central/south-central TX.  Wind profiles are very favorable for this activity to track northeast across the remainder of ww54 over the next several hours. New tornado watch will likely be issued immediately downstream by 01z to account for this evolution.

Mesoscale Discussion #0297


Concerning...Tornado Watch 54...


Valid 220024Z - 220200Z


The severe weather threat for Tornado Watch 54 continues.


SUMMARY...The severe threat continues across Tornado Watch 054. A QLCS tornado and damaging-wind threat is expected across the northern portions of the watch, while supercells with tornadoes (some possibly strong) should continue across central parts of the watch for at least a few more hours.


DISCUSSION...A QLCS is maturing across northern Texas per latest MRMS mosaic radar imagery. Meanwhile, at least 4 supercells with a history of producing tornadoes are ongoing across central Texas. Storms within both regimes are impinging on the western fringes of the low-level jet and associated strong low-level shear, which is likely supporting the relatively robust tornado production that has been observed over the past few hours. A moist, buoyant thermodynamic profile is accompanying the low-level jet per 23Z mesoanalysis, with over 2000 J/kg MLCAPE residing ahead of both the supercells and QLCS. 


Damaging winds and isolated tornado potential should continue with the QLCS through the remainder of the evening, including in areas east of the ongoing watch (please see Mesoscale Discussion #0296 for more details). Farther south, supercells are remaining discrete and are continuing in a favorable CAPE/shear environment for continued tornado production. It is possible that the Pacific front/dryline to the immediate west may catch up to the storms. In this case, the supercells may grow upscale into an MCS similar to what has happened farther north. However, Warn-on-Forecast high-resolution ensemble guidance suggests that supercells may remain discrete through 02Z. The best corridor for tornadic supercells may be from Falls/Lee County and points northeast, as storms farther to the south may be struggling due to weaker flow in the 850-700 mb layer.

Mesoscale Discussion #0310


Concerning...Tornado Watch 61...


Valid 221719Z - 221915Z


The severe weather threat for Tornado Watch 61 continues.


SUMMARY...One or two sustained, long track supercells with the potential to produce strong tornadoes may gradually begin to emerge across south central through east central Mississippi through 18-21Z, in advance of a squall line progressing east of the lower Mississippi Valley.


DISCUSSION...Strongest boundary-layer destabilization the past few hours has been focused along a corridor of stronger low-level warm advection, preceding the increasingly extensive cluster of thunderstorms slowly spreading into/across the lower Mississippi Valley.  This is contributing to deepening convective development across much of southern through central Mississippi, which likely will continue through the 18-21Z time frame.  Though the number of cells will probably decrease, stronger more widely scattered discrete storms probably will begin to emerge in an environment with CAPE increasing to 1500+ J/kg.  The continued inland and northward propagation of a strong southerly 850 mb speed maximum has and will continue to contribute to very large, clockwise curved low-level hodographs conducive to the evolution of sustained, strong mesocyclones with the potential to produce significant tornadoes. Given the strength of the south-southwesterly deep-layer mean flow, these will be fast moving (in excess of 50 kt) with the potential for one or two to become fairly long track.

Mesoscale Discussion #0312


Concerning...Tornado Watch 61...


Valid 222005Z - 222200Z


The severe weather threat for Tornado Watch 61 continues.


SUMMARY...Isolated supercell development remains possible inland of coastal areas, across southeastern Louisiana and Mississippi into the 4-6 PM CDT time frame.  This may pose the risk for producing tornadoes and/or locally damaging wind gusts.


DISCUSSION...To the south of a mesoscale convective vortex migrating northeast of Greenwood MS, rear inflow into the associated organized convective system has contributed to an eastward acceleration of outflow across much of northern and central Mississippi.  The southwestern flank of this outflow trails into the Mississippi/Louisiana state border area, south of Natchez, where it intersects a slower eastward advancing initial cold front, which trails into the northwestern Gulf of Mexico.  Southeast of these boundaries, a plume of seasonably moist boundary-layer air is contributing to moderate mixed-layer CAPE on the order of 1500-2000 J/kg, as far east as the southern Mississippi/Alabama border vicinity.


Although stronger mid/upper forcing for ascent now appears to be shifting northeastward, to the north of the Interstates 20/59 corridors (of central Mississippi/Alabama), much of the region remains beneath broadly difluent and cyclonic mid-level flow.  And southerly low-level flow remains strong as far south as coastal areas (including 50+ kt around 850 mb).  This regime probably will remain conducive to widely scattered discrete thunderstorm development, in advance of the frontal convective band, with occasional isolated supercells emerging, accompanied by the risk of producing tornadoes.

Mesoscale Discussion #0316


The severe weather threat for Tornado Watch 64 continues.


SUMMARY...An uptick in tornado potential may be developing in association with two maturing supercells in far southeast Louisiana. A strong tornado is possible.


DISCUSSION...Two discrete supercells continue to mature across the St. Tammany and Jefferson Parish areas, with KLIX radar data showing the development of more persistent mid-level mesocyclones (especially for the northern storm). The 00Z LIX observed sounding shows ample MLCAPE (1500 J/kg) driven by steep 850-600 mb lapse rates and 70+ F surface dewpoints. More so, the observed hodograph shows a long, curved shape, with over 400 m2/s2 effective SRH. Given the discrete and organized nature of the large supercells, a locally heightened risk of tornadoes exist. A significant tornado is possible given the magnitude of low level shear, with the St, Tammany Parish storm exhibiting a 40+ kt rotational velocity within the past few minutes.

Mesoscale Discussion #0328


Concerning...Tornado Watch 67...


Valid 232035Z - 232230Z


The severe weather threat for Tornado Watch 67 continues.


SUMMARY...Large hail and damaging winds remain possible with supercell thunderstorms in West Virginia and southeast Ohio. The tornado threat will be greatest along the West Virginia/Ohio border with more limited potential to the south and east.


DISCUSSION...Supercell thunderstorms continue to move northeastward into West Virginia from Kentucky. These storms will remain capable of large hail and damaging wind gusts. KPBZ and KRLX VAD winds continue to show 200-300 m2/s2 SRH which will continue to support some threat for tornadoes. At present, the greatest potential for a tornado over the next 1-2 hours will be along the West Virginia and Ohio border. The storm near Point Pleasant will continue northeast where temperatures are in the mid 70s F and dewpoints in the mid 50s F. Another severe storm south of Charleston will also progress into a similar environment in the short term. However, temperatures farther downstream are cooler and stable boundary-layer clouds are evident on visible satellite. The tornado threat with this southern storm will likely be shorter in duration.

Mesoscale Discussion #0354


Concerning...Severe potential...Watch likely 


Valid 301529Z - 301630Z


Probability of Watch Issuance...95 percent


SUMMARY...Intensifying thunderstorm development, including supercells, is expected through Noon-2 PM CDT, accompanied by a gradually increasing risk for tornadoes and potentially damaging wind gusts.


DISCUSSION...Strong southerly low-level flow, including speeds of 50-60+ kt around 850 mb, will be maintained across Louisiana coastal areas through much of the lower Mississippi Valley into this afternoon, in advance of a vigorous short wave trough pivoting in a negatively tilted fashion across the southern Great Plains.  In association with this regime, a more substantive influx of low-level moisture is ongoing off the northwestern Gulf of Mexico, across upper Texas coastal areas as far north as areas near/east of the Ark-La-Tex. This moistening is forecast to continue gradually spreading northeastward and eastward across the lower Mississippi Valley into this afternoon.


The latest Rapid Refresh suggests that substantive boundary-layer destabilization has already been occurring the past few hours across much of Louisiana.  As this persists and develops northeastward, coupled with strengthening large-scale ascent, weakening mid-level inhibition seems likely to allow for increasing and intensifying thunderstorm development.  In the presence of wind profiles including strong deep-layer shear and large clockwise-curved low-level hodographs, the evolution of a few supercell structures seems probable.  This may include within a developing line along an eastward advancing convectively enhanced surface boundary, and isolated discrete cells ahead of it, through 17-19Z.

Mesoscale Discussion #0356


Concerning...Tornado Watch 76...77...


Valid 301747Z - 301845Z


The severe weather threat for Tornado Watch 76, 77 continues.


SUMMARY...Severe thunderstorms posing increasing risk to produce tornadoes and/or strong, damaging wind gusts through 2-4 PM CDT. This may including increasing potential for a strong tornado or two by late afternoon.


DISCUSSION...Surface dew point increases through the mid 60s has now contributed to moderate mixed-layer CAPE of 1500+ J/kg along a narrow corridor of stronger 2 hourly (as of 17Z) surface pressure falls, from near Fort Polk LA into the Greenville MS area. Southerly flow around the 850 mb layer is forecast to continue to increase up to around 70 kt along and east of the this axis through 19-21Z, contributing to further enlargement of already sizable clockwise curved low-level hodographs.  With this coinciding with the sustained strong, and gradually intensifying, thunderstorm development, supercell structures with strong low-level mesocyclones will continue to evolve and pose increasing risk for tornadoes and/or localized strong damaging wind gusts.

Mesoscale Discussion #0363


Concerning...Tornado Watch 78...


Valid 302331Z - 310130Z


The severe weather threat for Tornado Watch 78 continues.


SUMMARY...Monitoring for a downscale evolution from squall line to supercell across southeast LA into far southern MS this evening.  If supercell development occurs and becomes sustained, the tornado risk for southeast LA into far southern MS would likely be heightened/most focused with any supercell.


DISCUSSION...Water-vapor imagery early this evening shows a mid-level dryslot punching into the lower MS Valley as a shortwave trough becomes negatively tilted over the Arklatex.  A 130 kt jet 250 mb streak centered over south TX will continue to move towards the central Gulf Coast region this evening and become more favorable for the evacuation of hydrometeors near updrafts, potentially favoring more cellular modes versus linear. Surface analysis indicates rich low-level moisture has inundated southeast LA into the MS/AL gulf coast with 68-70 deg F dewpoints observed at 6pm CDT.  Greater buoyancy resides across southeast LA into the coastal counties of southern MS/AL where 1000-1500 J/kg MLCAPE is indicated by 6pm RAP-based SPC objective analysis fields.


The combination of greater buoyancy and long hodographs will probably favor some transition to from primarily linear to a mix of linear and cellular modes.  Higher echo tops noted per KLIX imagery suggests this possible scenario could evolve over the next few hours.  The tornado risk will likely increase in tandem as the evolution of storms transitions to more cellular.  Damaging gusts will also accompany the stronger storms.

Mesoscale Discussion #0366


Concerning...Tornado Watch 80...


Valid 310133Z - 310230Z


The severe weather threat for Tornado Watch 80 continues.


SUMMARY...Locally higher tornado threat over the next 1 to 2 hours.


DISCUSSION...A supercell has developed strong low-level rotation in far northwest Greene County, Alabama. This cell will be absorbed by the main squall line in the next 15 minutes or so when it becomes less clear how the evolution will continue. At a minimum, an increased threat for significant wind is possible in the vicinity of this storm merger.


Farther south, a line embedded supercell is moving from Lauderdale county Mississippi into Sumter county, Alabama. This storm has had the tallest echo tops for awhile, and has had a few TDS observed across Lauderdale county. The environment ahead of this storm remains favorable for tornadoes. In fact, low-level flow has recently backed in this region which further increases low-level streamwise vorticity. Therefore, this storm will continue to pose a tornado threat, and potentially a strong tornado threat over the next 1 to 2 hours.

Mesoscale Discussion #0367


Concerning...Tornado Watch 80...


Valid 310144Z - 310345Z


The severe weather threat for Tornado Watch 80 continues.


SUMMARY...Increasing tornado potential for parts of southwest and central AL through 1030 pm CDT as warm sector supercells develop ahead of the convective band.


DISCUSSION...Radar imagery from KMOB shows developing supercells over Clarke and Marengo Counties as of 840pm CDT.  These storms have recently developed within the warm conveyor belt within an environment characterized by intense low- to mid-tropospheric wind fields (per KBMX 88D VAD data) and weak but increasing buoyancy. The low-level moisture contribution to buoyancy will be the key factor in the conditionality of tornado potential with these storms. It appears the northern rim of mid 60s deg F dewpoints is near this activity.  Very strong low-level moisture advection via 50-60 kt 1-2 km southerly flow will act to destabilize the airmass immediately downstream of these storms.  As a result of an increasingly favorable environment, tornado potential will likely begin to focus over central AL during the next 2 hours with these warm sector supercells.  A strong tornado is possible, especially if updrafts can further intensify/mature.

Mesoscale Discussion #0368


Concerning...Tornado Watch 82...


Valid 310150Z - 310245Z


The severe weather threat for Tornado Watch 82 continues.


SUMMARY...A significant tornado threat is materializing across southeast Mississippi and southwest Alabama.


DISCUSSION...Several mature supercells have emerged from the squall line across Wayne, Perry, and Greene counties in southeast Mississippi. The tornadic environment ahead of these storms is improving substantially with a STP bullseye around 4 near these storms. Low-level convergence has strengthened considerably in the vicinity of each of these supercells. Therefore, given storm trends and the increasingly favorable tornadic environment ahead of these storms, the strong tornado threat is increasing.

Mesoscale Discussion #0370


Concerning...Tornado Watch 82...


Valid 310257Z - 310500Z


The severe weather threat for Tornado Watch 82 continues.


SUMMARY...Increasing confidence in the severe threat (significant wind damage and tornado risk) with a couple of embedded supercells as they moves across southwest AL through 12am CDT.


DISCUSSION...KMOB radar imagery shows a couple of supercells embedded in the convective line over southwest AL/far southeast MS in proximity to a very moisture rich airmass.  Surface observations show dewpoints in the upper 60s deg F.  Very strong low-level wind fields increasing with height will favor supercellular mode, despite a convective line contributing to a messy/erratic low-level rear-flank downdraft structure.  Recent Warn-on-Forecast guidance has highlighted this general corridor across southwest AL with model ensemble Updraft Helicity swaths.  Observations in terms of an intense storm in southwest AL seem to be aligning with this guidance thus far.  Current expectation is for both the tornado and damaging wind threat to increase despite HP structure as they move east-northeast over the next couple of hours.

Mesoscale Discussion #0371


Concerning...Tornado Watch 80...


Valid 310320Z - 310445Z


The severe weather threat for Tornado Watch 80 continues.


SUMMARY...Significant tornado threat will likely continue in central AL through 12am CDT.


DISCUSSION...An intense pair of supercells will likely move northeast across parts of central AL during the next 1-2 hours. The warm sector supercells will continue to reside in an increasingly moisture-rich airmass (mid 60s deg F surface dewpoints) and buoyant environment co-located with intense low- to mid-level flow. A significant tornado risk will likely accompany these storms.

Mesoscale Discussion #0374


Concerning...Tornado Watch 84...


Valid 310854Z - 311100Z


The severe weather threat for Tornado Watch 84 continues.


SUMMARY...A threat for damaging wind gusts, isolated large hail and a tornado or two will continue early this morning across parts of southeast Alabama, southwest Georgia and the Florida Panhandle. New watch issuance will need be to considered to the east of the current watch.


DISCUSSION...Latest mosaic radar imagery shows an organized convective line extending from near Dothan, Alabama extending north-northeastward to Columbus, Georgia. A shortwave trough with a band of large-scale ascent is located over far southwest Georgia, evident on water-vapor imagery. This feature will move northeastward this morning into south-central Georgia providing support for continued thunderstorm development. In addition, the WSR-88D VWP out of Valdosta, Georgia has 0-6 km shear near 65 kt with a looped hodograph. This will be favorable for supercells embedded in the line with a potential for tornadoes. These storms could also produce wind damage and isolated large hail, especially with segments that obtain bowing structure.  The severe threat should continue through daybreak. New weather watch issuance may become necessary to the east of WW 84.


**Note: This MCD preceded the  Wausau, Florida EF3

Mesoscale Discussion #0406


Concerning...Severe potential...Tornado Watch likely 


Valid 051515Z - 051715Z


Probability of Watch Issuance...95 percent


SUMMARY...A threat for several tornadoes and numerous damaging winds will spread eastward this afternoon. Some of the tornadoes could be strong. Tornado Watch issuance will be needed.


DISCUSSION...A small bowing complex with a history of producing damaging winds and embedded tornadoes is moving eastward across southern AL this morning. A couple of low-topped supercells are also present ahead of the line. Recent visible satellite trends show a fair amount of mid and high-level cloudiness downstream of this activity across much of GA and parts of the FL Panhandle. Even so, the airmass across this region is expected to destabilize enough to support surface-based storms this afternoon. 15Z surface observations show temperatures rising into the upper 60s and 70s, with dewpoints gradually increasing into the 60s. MLCAPE should increase into the 500-1500 J/kg range as this occurs, even though mid-level lapse rates should remain fairly modest.


A 40-50+ kt south-southwesterly low-level jet will spread eastward over GA this afternoon. A strongly veering and strengthening wind profile with height through mid levels will likely support updraft rotation both within the line and with any cells that can remain discrete ahead of it. Given the enhanced low-level shear, a threat for tornadoes will likely exist, especially with any supercells that can remain at least semi-discrete. A strong tornado will remain a possibility with favorably enhanced low-level hodographs. The bowing line of convection should also remain capable of producing numerous damaging winds. Based on recent radar trends, Tornado Watch issuance across parts of southern/central GA and vicinity appears increasingly likely by 16-17Z (12-1 PM EDT).

Mesoscale Discussion #0408


Concerning...Tornado Watch 95...


Valid 051545Z - 051715Z


The severe weather threat for Tornado Watch 95 continues.


SUMMARY...The greatest severe threat, including the potential for strong tornadoes, should focus across parts of southeastern Alabama in the next 1-2 hours.


DISCUSSION...A small bowing line and two leading supercells ahead of it will continue to move eastward across parts of southeastern AL this morning. The low-level airmass ahead of this activity is not overly unstable, but boundary-layer instability will probably be sufficient for a persistent severe threat. Recent VWPs from KMXX and KEOX show a very favorable low-level wind profile, with 0-1 km SRH exceeding 400 m2/s2. Indeed, strong low-level rotation has been noted with both leading supercells, and a tornado threat remains apparent. A strong tornado also remains a possibility given the strength of the low-level flow and enhanced hodograph in the 0-3 km layer. Damaging winds should be a threat with the bowing line as well.

Mesoscale Discussion #0415


Concerning...Tornado Watch 96...98...


Valid 052022Z - 052145Z


The severe weather threat for Tornado Watch 96, 98 continues.


SUMMARY...The greatest threat for strong tornadoes should focus across parts of east-central Georgia into South Carolina over the next 1-2 hours.


DISCUSSION...Multiple tornadic circulations with TDS markers have recently been observed from the KJGX radar with a broken line of storms in central GA. A separate TDS and very strong low-level rotation was also noted earlier with a supercell over Allendale County SC. The core of a 40-50 kt south-southwesterly low-level jet overlies this region, and ample low-level shear is present to support updraft rotation and tornado potential. The northern extent of the surface-based thunderstorm and substantial tornado threat will likely be constrained by a surface warm front that is draped southwest to northeast across central SC. The presence of mid to upper 60s and even some low 70s surface dewpoints with filtered diurnal heating is supporting MLCAPE from 500-1000 J/kg, which is more than sufficient for surface-based convection. The threat for strong tornadoes in the next 1-2 hours will likely be greatest with any supercells that can mature ahead of the line across east-central GA into parts of central/coastal SC. Embedded tornadoes within the line may also be capable of becoming strong given 300-400 m2/s2 of 0-1 km SRH per recent VWPs from KJGX and KCLX.

Mesoscale Discussion #0418


Concerning...Tornado Watch 98...99...


Valid 052230Z - 060000Z


The severe weather threat for Tornado Watch 98, 99 continues.


SUMMARY...Tornadic supercells ahead of the squall line will continue to pose a threat for significant tornadoes over the next 1-2 hours across southern South Carolina.


DISCUSSION...Supercells ahead of an approaching squall line have maintained intensity and organization over the past hour. The effects of downstream diabatic cooling continue to be overcome by strong kinematics ahead of the parent cyclone to the north/northwest. Favorable low-level moisture (60+ F dewpoints) outlining the effective warm sector is matching the forward speed of these supercells, maintaining an environment with around 1000 J/kg MLCAPE and 300-400 m2/s2 0-1 km SRH (based on regional VWPs). This will support a continued tornado threat for the next 1-2 hours, possibly lasting into the mid to late evening hours for portions of coastal SC. Given the kinematic environment and VROT values noted with recent circulations, a couple of significant tornadoes are possible.

Mesoscale Discussion #0447


Concerning...Severe potential...Watch likely 


Valid 111934Z - 112130Z


Probability of Watch Issuance...80 percent


SUMMARY...Scattered strong to severe storm development is likely over the next few hours. Scattered damaging gusts, very large hail, and a few tornadoes are all likely, and a strong tornado or two is also possible. A Tornado Watch issuance will be needed soon.


DISCUSSION...An elongated 1006 mb surface low continues to meander east across northern Texas, with the triple point situated along the Red River near GLE, and a quasi-stationary baroclinic zone draped along a line roughly from ADM to FSM per latest surface observations. A deepening cumulus field has already become established across eastern OK into northeast TX and western AR. The approach of a modest 500 mb vort max over the Southern Plains combined with adequate diurnal heating should foster an increase in thunderstorm development near the triple point and along the quasi-stationary baroclinic zone over the next few hours. The last few deterministic HRRR and Warn-on-Forecast ensemble runs suggest that storms may become established as early as 20Z. 8.5 C/km mid-level lapse rates overspreading mid 60s F surface dewpoints are contributing to over 2000 J/kg MLCAPE, with MLCINH continuing to erode with time. 


Modest veering/strengthening of the surface-700 mb flow yields modestly curved hodographs (via SRX and LZK VAD profilers), with supercell structures likely given the initial discrete storm mode expected. Damaging gusts and large hail may accompany any storm that can mature, and 2+ inch hail may also accompany the longer-lived robust supercells given the steep mid-level lapse rates. While the low-level jet continues to weaken and shift eastward towards the MS River, enough low-level directional shear should promote low-level rotation and tornado potential with the more persistent supercells. If supercells can remain discrete while propagating eastward into AR (closer to the low-level jet axis), a strong tornado or two may also occur. A Tornado Watch will be needed soon.

Mesoscale Discussion #0449


Concerning...Tornado Watch 107...


Valid 112237Z - 120030Z


The severe weather threat for Tornado Watch 107 continues.


SUMMARY...An isolated supercell may persist for several more hours, moving eastward near/north of the Interstate 40 corridor east of Fort Smith into the Little Rock area through 7-9 PM.  This will continue to pose a risk for tornadoes, one or two possibly strong, with some potential to begin to grow upscale with severe wind becoming more prominent later this evening.


DISCUSSION...The axis of the primary mid-level short wave trough appears to be progressing to the east of the region, and likely to continue across and east of the Mississippi River into the lower Ohio Valley through early evening.  As this occurs, more prominent mid-level height rises are forecast across the southeastern Great Plains and Ozark Plateau, with the northern periphery of warmer and more strongly capping elevated mixed-layer air shifting northward toward the I-40 corridor through 00-02Z.  This seems likely to become the primary focus for continuing stronger thunderstorm development, aided by continuing forcing for ascent associated with lower/mid tropospheric warm advection.  The boundary-layer along this corridor likely has reached peak late afternoon instability, including CAPE on the order of 1500-2500+ J/kg.  


Given this instability, modest clockwise curved low-level hodographs and strong deep-layer shear, beneath 30-50 kt southerly to westerly flow in the 850-500 mb layer will remain conducive to discrete supercell development.  The westerly component to the deeper layer mean flow may be contributing to the the eastward propagation of the one significant ongoing supercell now east of Fort Smith.  It appears that this could be maintained for several hours, coincident with a near-surface thermal gradient associated with the remnants of a previous outflow boundary, providing an environment favorable for at least periodic, if not sustained, potential tornadic development.

Mesoscale Discussion #0450


Concerning...Severe Thunderstorm Watch 108...


Valid 112346Z - 120115Z


The severe weather threat for Severe Thunderstorm Watch 108 continues.


SUMMARY...The severe risk continues across WW108. Supercells capable of all hazards will continue east-northeast into WW107.


DISCUSSION...Regional radar and surface analysis showed several supercells ongoing across southeastern Oklahoma in the vicinity of a subtle warm front lifting through the ArkLaTex. Ahead of these storms the airmass remain warm, moist, and unstable with low to mid 60s F dewpoints and 2000-3000 J/kg of MLCAPE. Regional VWPs show 40-50 kt of effective shear which will continue to support updraft organization/rotation as these storms move east-northeastward. In addition to the favorable mid-level shear, VWPs show increasingly large low-level hodographs with eastward extent. Given the favorable mode and the expected increase in 0-1km ESRH with the developing nocturnal low-level jet, low-level mesocyclone strengthen and the subsequent tornado threat may increase as storms move out of WW108 into WW107. Otherwise, these supercells remain capable of producing large to very large hail and damaging wind gusts.


Latest radar and visible imagery also show several attempts at discrete warm sector Ci across far southeastern OK and western AR. Likely driven by subtle confluence near the aforementioned lifting warm front, any supercells able to become established within the free warm sector would likely pose a risk for tornadoes this evening given STP values of 3-4 from the latest SPC mesoanalysis.

Mesoscale Discussion #0457


Concerning...Severe potential...Tornado Watch likely 


Valid 121948Z - 122115Z


Probability of Watch Issuance...95 percent


SUMMARY...Convective initiation is expected by around 21-23z. A tornado watch will likely be needed in the next hour or so. Severe thunderstorms capable of large hail, damaging gusts and a few tornadoes are possible.


DISCUSSION...A surface low is located near the central NE/SD border as of 19z. A warm front was noted in surface analysis arcing from the low across northeast NE into southern IA. Meanwhile, the surface cold front was located across central NE and rapidly approaching the surface dryline just a few counties to the east. Increasing cumulus has been noted in visible satellite imagery along the dryline and across the warm sector to the east across northeast NE. The cumulus along the dryline has shown modest vertical development where capping is likely less than further east. As the warm front continues to lift northward and better quality boundary-layer moisture works northward in conjunction with strong large-scale ascent, convection is expected to develop near the triple point by 21-23z. 


Initial convection across southeast SD into southwest MN to near the NE/IA border may be elevated near/just to the cold side of the warm front, with a better-quality warm sector remaining quite narrow from near the MO River into northwest IA. Fast storm motion toward the northeast could result in these storms rapidly moving away from the better warm sector as they mature. Nevertheless, strong vertical shear, steepening midlevel lapse rates and sufficient instability should support organized supercells capable of large hail and perhaps strong gusts. Any storm that develops in the better warm sector or that can anchor to the warm front will access better low-level shear and see an increased risk for tornado development. Furthermore, any storm that develops further south along the cold front/dryline in NE may be higher-based, posing a threat for large hail and damaging gusts. If any dryline convection persists eastward into better moisture, these cells also could become surface-based within the better-quality warm sector with a corresponding increase in tornado potential. With time into the evening, more linear convective development is expected near/east of the MO River as the cold front surges east.

Mesoscale Discussion #0458


Concerning...Severe potential...Watch likely 


Valid 122007Z - 122200Z


Probability of Watch Issuance...80 percent


SUMMARY...The tornado threat is expected to increase into the evening hours across parts of central Texas.


DISCUSSION...One supercell and several additional cells have developed along and near the dryline in west-central Texas this afternoon. Storms organization has been slow, likely due to the convoluted wind profile in the wake of the passing upper-level trough. However, deep layer flow is expected to improve into this evening with 45 to 50 knots of effective shear forecast across the warm sector by 23Z. Additionally, current storm activity is in a well-mixed airmass with 30+ F temperature-dewpoint spreads and veered surface flow. As these storms move east, they will encounter a less mixed airmass with backed surface flow and dewpoints in the upper 60s. These south-southeasterly surface winds combined with strengthening lower tropospheric flow, will likely result in a low-level wind profile favorable for tornadoes. Therefore, a tornado watch will likely be needed east of watch 110 late this afternoon into the early evening hours.

Mesoscale Discussion #0459


Concerning...Tornado Watch 112...


Valid 122232Z - 130000Z


The severe weather threat for Tornado Watch 112 continues.


SUMMARY...Ongoing severe storms including supercells are gradually moving into a more moist and unstable thermodynamic environment near I-35. Increasing shear with time may also favor an enhanced tornado threat with more discrete convection farther south along the dryline in WW112.


DISCUSSION...As of 2225 UTC, regional radar showed a cluster of severe thunderstorms and several semi-discrete supercells ongoing along the US-281/I-35 corridor. Ahead of these storms low-level moisture gradually increases with upper 60s to low 70s F dewpoints now present. 3000-3500 J/kg of MLCAPE will continue to support robust updrafts as this cluster moves east. Coincident with the improving thermodynamics, strong flow aloft near a southern stream shortwave trough over east Texas is enhancing mid-level shear profiles. Regional VWPs show storms are entering 35-45 kts of effective shear more supportive of semi-discrete/rotating updrafts. Recent radar trends point to greater organization within the cluster over the last 15 minutes especially with two semi-discrete cells in the vicinity of Waco. While low-level shear is not overly strong, VAD hodographs and surface obs show backed low-level flow with a large component of streamwise vorticity within the effective inflow layer. Tornado potential may be increasing as storms move farther east into a lower LCL and stronger sheared environment. In addition, large hail and damaging winds will remain likely given the magnitude of the buoyancy and very steep lapse rates aloft.


Greater uncertainty exists on the southern end of the cluster where discrete initiation has occurred near San Antonio. Displaced from stronger forcing, these updrafts have been slow to organize but may strengthen as they move farther east into better moisture.

Mesoscale Discussion #0460


Concerning...Tornado Watch 111...113...


Valid 122245Z - 130045Z


The severe weather threat for Tornado Watch 111, 113 continues.


SUMMARY...Sustained strong supercells appear increasingly likely through early evening.  Some probably will pose a risk for producing tornadoes, particularly around the Storm Lake and Fort Dodge IA areas by 7-9 PM CDT, where a strong tornado or two is possible. Additional, a severe thunderstorm watch will probably be issued soon to the north of the current watch, where severe hail may become an increasing concern this evening.


DISCUSSION...Thunderstorms are now initiating along the warm frontal zone, north through east of a deep surface cyclone slowly migrating east-northeast of the Sioux City area.  This is being supported by lift driven by low-level warm advection, and perhaps a subtle mid-level perturbation forecast to migrate north-northeastward across the mid Missouri Valley around Sioux City through early evening.


The strongest thunderstorms probably will tend to evolve along the front to the east-southeast of the warm front/dryline intersection, now generally east of the Missouri River, where a narrow tongue of modest boundary-layer moistening wrapping toward the surface low center may be contributing to mixed-layer CAPE as high as 3000 J/kg to the southwest of Fort Dodge.  Into the the 00-02Z time frame, southerly 850 mb flow across the narrow warm sector, into and across the warm frontal zone is forecast to strengthen to 50-60+ kt, contributing to very large, clockwise curved low-level hodographs.


As this occurs, the warm frontal zone is expected to become the focus for intensifying supercells, including the evolution of strong low-level mesocyclones, potentially capable of producing tornadoes. The warm front is rather sharp, and the air to the north of the front rather cool and stable.  However, the front is slowly advancing northward, and model forecast soundings indicate low-level thermodynamic profiles will destabilize across much of northwestern through north central Iowa into early evening.  It appears possible that this will become sufficient for tornado development, with highest probabilities for sustained/longer track tornadic supercell development around the Storm Lake/Fort Dodge Iowa vicinities.


As storms progress north of the warm frontal zone, into the colder air, stronger cells could continue to pose a risk for severe hail while the tornado threat diminishes.

Mesoscale Discussion #0471


Concerning...Severe potential...Watch possible 


Valid 131205Z - 131430Z


Probability of Watch Issuance...60 percent


SUMMARY...Additional storm development/intensification is likely this morning.  A tornado watch will probably need to be considered for parts of this region later this morning.  Isolated large hail will be the primary risk with the initial strong/severe storms.


DISCUSSION...Water-vapor imagery this morning shows an intense mid-level shortwave trough moving east through the TX Panhandle as it moves through the base of a larger-scale trough over the central U.S.  Radar imagery during the past hour has shown a pronounced increase in storm development both along the cold front over central OK and in the warm sector in a pre-frontal band of developing storms over north-central TX.  


Surface analysis indicates an outflow boundary is draped from parts of central MS westward into northern LA and into far northeast TX in wake of a MCV and associated MCS that moved across the Arklatex/Arklamiss during the overnight. The airmass over northeast TX and southeast OK is moderately unstable with surface dewpoints in the upper 60s as rich low-level moisture advects north-northeast on the western periphery stable low levels.  


Increasing forcing for ascent and strengthening deep-layer shear will favor additional storm development/organization over the next several hours.  Large hail will be the primary threat prior to storms transitioning to becoming surface based late this morning. Although timing of a surface-based transition is uncertain at this time (most likely 10am-12pm), the severe risk will correspondingly evolve to some tornado threat developing with an evolution to maturing supercells.

Mesoscale Discussion #0476


Concerning...Severe potential...Tornado Watch likely 


Valid 131732Z - 131930Z


Probability of Watch Issuance...80 percent


SUMMARY...Rapid destabilization is expected across portions of the Ohio and Mid-Mississippi Valley


DISCUSSION...A stable airmass is currently in place across the lower Ohio Valley and mid-Mississippi Valley in the wake of a morning MCV. However, low-level moisture is expected to improve significantly over the next several hours. The leading edge of richer Gulf moisture can now be seen on visible satellite where the cu field is expanding north across Mississippi and western Alabama. Extrapolating northward movement of this better moisture and northeastward movement of ongoing thunderstorm activities, it appears better low-level moisture will arrive prior to the convective line east of the Mississippi River and possibly slightly west. Expect this better moisture to reach the Missouri bootheel around 19-20Z, southern Illinois 20-21Z and southern Indiana around 22Z. MLCAPE is expected to increase to the 1000 to 2000 J/kg range ahead of these storms which should be sufficiently unstable to not only support a significant severe weather threat with the squall line, but also potentially allow for some more discrete convection to develop ahead of the line. In addition, surface winds are expected to back across the warm sector as the upper-level trough advances northeastward. Therefore, significant elongation of the low-level hodographs is anticipated. Therefore, all severe weather hazards are expected this afternoon/evening including the potential for 75+ mph wind gusts and a couple of strong (EF2+) tornadoes. A tornado watch will likely be issued in the next 1 to 2 hours.

Mesoscale Discussion #0483


Concerning...Tornado Watch 122...124...


Valid 132148Z - 132345Z


The severe weather threat for Tornado Watch 122, 124 continues.


SUMMARY...An organized squall line will continue to push east into middle Tennessee and southern Kentucky over the next couple of hours. The greatest near-term tornado potential will reside ahead of a bowing segment in southwestern Kentucky, but damaging winds and brief embedded tornadoes remain possible along the entire line.


DISCUSSION...The line of storms that has emerged from northeast AR is now a well-organized squall line with a balanced inflow/outflow convergence zone from western KY into the Memphis, TN area. Several embedded circulations have been noted over the past hour within the line, and wind damage has also been reported. In general, the overall convective environment immediately downstream of this line remains favorable for QLCS maintenance as MLCAPE continues to slowly increase (up to 1000-1500 J/kg per latest RAP mesoanalysis and forecast soundings) with 45-55 knot effective bulk shear over the region. As such, the severe threat will likely persist into middle TN and southern KY in the coming hours.


The most severe section of the line resides across southwestern KY where a bowing segment is noted immediately south of a broad book-end vortex (noted in recent KPAH imagery). This bowing segment will not only be favorable for widespread damaging winds, but is oriented more orthogonal to low-level shear vectors, which is supportive of embedded circulations and brief tornadoes. Forecast soundings suggest the veering 0-3 km hodograph structure noted in KHPX VWP observations will persist through at least 00Z, which will maintain the tornado threat. Further south along the line, embedded circulations remain possible, but will be conditional on more meridional line re-orientations. To address this tornado potential a downstream tornado watch will likely be needed soon.

Mesoscale Discussion #0491


Concerning...Severe Thunderstorm Watch 127...


Valid 140140Z - 140245Z


The severe weather threat for Severe Thunderstorm Watch 127 continues.


SUMMARY...A QLCS is expected to pose a risk for damaging wind gusts and isolated tornadoes as it moves to the east southeast. A corridor of enhanced damaging wind potential maybe developing with a bowing segment across eastern MS.


DISCUSSION...As of 0130z a fast moving QLCS was located across eastern MS near the border with AL. Recent reports of damaging wind gusts (some 75+ mph) have occurred with a bowing segment within the line. As the line shifts eastward into a drier low-level thermodynamic environment across western AL (dewpoints in the low 60s F), significant damaging wind potential may be developing. Hi-res guidance and observation trends suggests the southern most portion of the line will become dominant as it slides southeastward into the corridor of better low-level moisture advection across southwestern AL. Sufficient buoyancy and vertical shear exist to support a continued severe threat with the QLCS this evening. One uncertainty remains the potential for tornadoes. While low-level shear remains fairly strong (0-1km SRH of 100-200 m2/s2) the drier low-level environment and weaker buoyancy may favor stronger outflow and limit the potential for tornadoes with eastward extent.

Mesoscale Discussion #0582


Concerning...Severe potential...Tornado Watch likely 


Valid 291923Z - 292200Z


Probability of Watch Issuance...80 percent


SUMMARY...Monitoring for supercell development along the dryline this afternoon. Strong tornadoes, very large hail, and damaging gusts will all be possible with this activity. A Tornado Watch will likely be needed for parts of the area.


DISCUSSION...Water vapor imagery indicates a strong midlevel speed maximum approaching KS/OK, where modest midlevel height falls are occurring. As this speed maximum continues overspreading the area, a NNE-SSW oriented dryline will sharpen across east-central KS into north-central OK. The strengthening dryline circulation, combined with south-southwesterly low-level flow oriented largely parallel to the dryline should allow for isolated convective initiation between 20Z-23Z. Surface dewpoints in the middle/upper 60s F beneath very steep midlevel lapse rates will support a strongly unstable airmass (MLCAPE nearing 3000 J/kg), while effective bulk shear increases to around 40 knots. These factors, coupled with strongly veering wind profiles in the boundary-layer (200-300 m2/s2 effective SRH) would certainly favor supercells capable of strong tornadoes, very large hail, and damaging gusts. There is still some uncertainty in the overall coverage and location of the severe threat, though trends will continue to be monitored for Tornado Watch issuance for parts of this area.

Mesoscale Discussion #0583


Concerning...Severe potential...Tornado Watch likely 


Valid 292146Z - 292245Z


Probability of Watch Issuance...95 percent


SUMMARY...There is increasing confidence in a storm or two initiating along the dryline in western Oklahoma. Very large hail and tornadoes will be possible. A tornado watch will likely be needed shortly.


DISCUSSION...Temperatures west of the dryline Oklahoma and northwest Texas have risen to the upper 90s F to around 100 F near Altus, OK. Visible satellite continues to show towering cumulus developing from near Frederick, OK to near Watonga, OK. Given the nearly stationary nature of the dryline and the low-level parcel trajectories, it seems that residence time in the dryline circulation should be sufficient for a storm or two to develop this afternoon. Effective shear vectors are orthogonal to the boundary at 40-50 kts. Storms should be discrete. The 21Z OUN sounding showed a near 9 C/km lapse rate in the mid-levels. Furthermore, the capping inversion has weakened slightly. Very large hail will be a possibility. As dewpoints have largely remained in the mid/upper 60s F and the low-level jet expected to increase in central Oklahoma this evening, tornadoes, perhaps strong, are also possible. A tornado watch will likely be needed shortly.

Mesoscale Discussion #0585


Concerning...Tornado Watch 158...


Valid 292354Z - 300130Z


The severe weather threat for Tornado Watch 158 continues.


SUMMARY...A storm or two may still initiate along the dryline west of Wichita. Tornadoes and large/very-large hail would be possible with these discrete storms. Additional convection is possible as the cold front moves through the area later this evening. Convection along the cold front would pose more of a damaging-wind threat.


DISCUSSION...Cumulus development has continued to increase to the west of Wichita. Recent KICT radar imagery shows weak, but steadily increasing reflectivity presentation with this activity. While upper-level forcing is not as strong as to the north, there remains a window over the next few hours where storms could mature this evening. The KICT VWP shows 0-1 km SRH in excess of 200 m2/s2. Tornadoes as well as large to very large hail would be possible with these discrete storms. There does remain some uncertainty on storm coverage as temperature in the warm sector have cooled slightly and objective analysis shows a coincident increase in MLCIN.


Later this evening, the cold front, reinforced by convective outflow, will move through the area. Given the linear forcing, wind damage would then become the primary threat along with a more isolated risk for large hail and QLCS tornadoes.


**Note: This MCD preceded the  Andover, Kansas EF3

Mesoscale Discussion #0589


Concerning...Tornado Watch 158...


Valid 300158Z - 300400Z


The severe weather threat for Tornado Watch 158 continues.


SUMMARY...Wind damage is expected to become the primary risk with time as the cold front moves east. QLCS tornadoes will also remain possible. The greatest tornado risk in the short term will exist with discrete convection east of Wichita. A new watch south and east of these areas may be needed as the cold front moves into those areas.


DISCUSSION...Convection has increased along the advancing cold front in easter Kansas. KTWX and KICT radars continue to show several line-embedded circulations. A few reported tornadoes have occurred along the line in the last hour. With the downstream environment remaining favorably sheared at low-levels, some threat for QLCS tornadoes will continue this evening. However, the primary threat with the linear convection should be damaging winds.


Farther south, east of Wichita, two discrete supercells continue east-northeastward. One of these cells produced a tornado near Augusta, KS around 820 CDT and another near El Dorado around 847 CDT. These discrete storms will pose the greatest tornado threat over the next couple of hours. With time, the cold front will eventually undercut these storms. Again, damaging winds will become the primary threat as this occurs along with a secondary threat of QLCS tornadoes.


The expectation is for the convection along the cold front to build southwestward to some degree later this evening. This will place a few strong to severe storms into parts of north-central and northeast Oklahoma towards midnight. However, with capping increasing with southward extent, it is not clear how far south this activity will reach. Nevertheless, there is potential for a new watch to be issued that would include parts of northern Oklahoma and southwest Missouri.

Mesoscale Discussion #0607


Concerning...Severe potential...Watch likely 


Valid 011804Z - 012030Z


Probability of Watch Issuance...95 percent


SUMMARY...The threat for very large hail, damaging winds, and perhaps a few tornadoes will increase as thunderstorms develop this afternoon. Some of the very large hail could be 3 to 4+ inches in diameter. Watch issuance will likely be needed in the next couple of hours.


DISCUSSION...Low-level moisture continues to stream northward early this afternoon in tandem with a 20-25 kt southeasterly low-level jet across parts of west TX and vicinity. Diurnal heating of this moist airmass and the presence of rather steep mid-level lapse rates indicated on the 12Z MAF sounding are already supporting MLCAPE of 1500-2000 J/kg as of 18Z. Additional heating and surface dewpoints generally increasing into the low to mid 60s will likely foster even stronger instability by late afternoon, with MLCAPE of 2500-3500 J/kg possible. The east-southeasterly low-level upslope flow will likely aid convective initiation across the higher terrain of southeastern NM and west TX over the next couple of hours. A veering and strengthening wind profile with height through mid levels will support around 40-50 kt of effective bulk shear, with considerable speed shear noted at mid/upper levels in various NAM/RAP forecast soundings across this region.


This favorable thermodynamic and kinematic environment will easily support scattered supercells with an attendant threat for very large hail. Some of the this hail could be 3 to 4+ inches in diameter given the large reservoir of buoyancy that will be available, presence of steep mid-level lapse rates, and long/straight hodographs in the 3-9 km layer. Although the low-level flow is fairly modest at the moment, some strengthening of the southeasterly low-level jet is forecast by early evening. As low-level hodographs correspondingly increase/lengthen, there should be a risk for a few tornadoes, especially along/near the northward-advancing warm front. Severe/damaging winds could also become a concern as supercells may eventually congeal into small bowing clusters across parts of the Edwards Plateau this evening. Observational trends will be closely monitored for signs of convective initiation across west TX, and a watch will likely be needed in the next couple of hours.

Mesoscale Discussion #0622


Concerning...Severe potential...Tornado Watch likely 


Valid 021830Z - 022030Z


Probability of Watch Issuance...95 percent


SUMMARY...The severe threat will rapidly increase this afternoon. Tornadoes, some of which could be strong, significant damaging winds, and very large hail all appear likely. Tornado Watch issuance will be needed by 20Z (3 PM CDT).


DISCUSSION...A surface low is present over southwestern KS at 1830Z, with a dryline extending southward from the low across the far eastern TX Panhandle into western OK. An effective warm front/outflow boundary from earlier convection extends southeastward from the surface low into northwestern and central OK. Surface temperatures have generally warmed into the 70s and low 80s along/south of this boundary, with dewpoints increasing into the low to mid 60s. At least isolated thunderstorms are expected to initiate along the dryline across northwestern OK by 20Z (3 PM CDT), as forcing for ascent associated with a shortwave trough over the central High Plains overspreads the warm sector.


Modestly steepened mid-level lapse rates overlying the moist low-level airmass and continued diurnal heating will likely support moderate to strong instability by late afternoon, with MLCAPE ranging from around 2000-3000+ J/kg. Veering/strengthening wind profiles with height through mid levels will easily support supercells with initial development off the dryline. Effective SRH of 200-250+ m2/s2 this afternoon will foster low-level rotation with any thunderstorms that develop, with a corresponding threat for tornadoes. Some of the tornadoes could be strong given the rather favorable thermodynamic and kinematic environment, especially along the effective warm front/outflow boundary from earlier convection. Very large hail will also be possible with any supercells that can persist and remain at least semi-discrete.


The most probable area for initiation will be close to the surface triple point in northwestern OK, where the cu field is already becoming agitated. Most high-resolution guidance continues to suggest one or more intense supercells will form across this region and spread eastward into north-central OK this afternoon and early evening. The greatest threat for strong tornadoes will likely be associated with this activity. The potential for additional convective development farther south along the dryline across west-central OK remains unclear, as the better forcing associated with the compact shortwave trough and mid-level jet should remain focused along/near the OK/KS border area. Still, if a thunderstorm or two can form farther south, they would likely become severe quickly while also posing a threat for tornadoes and very large hail.


The supercells across north-central OK should grow upscale into a bowing squall line this evening, with a continued threat for embedded tornadoes and significant severe/damaging winds as convection spreads east-southeastward into central/eastern OK. Tornado Watch issuance will be needed by 20Z (3 PM CDT), as convective initiation across northwestern OK appears likely by this time.

Mesoscale Discussion #0624


Concerning...Tornado Watch 171...


Valid 022032Z - 022200Z


The severe weather threat for Tornado Watch 171 continues.


SUMMARY...The greatest threat for tornadoes and very large hail should focus across parts of southern Kansas and northwestern Oklahoma through 5 PM CDT.


DISCUSSION...A supercell has developed over part of southwestern KS in close proximity to the surface low, with large hail up to 1.75 inches in diameter reported so far. Other convection has initiated along the dryline in northwestern OK and is gradually intensifying into supercells. Recent VWPs from KVNX show a strengthening wind profile with height through mid levels, with around 200 m2/s2 of 0-1 km SRH and 50+ kt of deep-layer shear. Even stronger low-level SRH may be present farther east into north-central OK along/near the effective warm front. Any supercells that can remain at least semi-discrete will continue to pose a threat for very large hail (2 to 3 inch diameter) and tornadoes as they move eastward over the next hour or two given this favorable low-level and deep-layer shear, and the presence of 1000-2500 J/kg of MLCAPE. Greater boundary-layer instability is present over northwestern into north-central OK in a fairly narrow corridor, where robust heating is occurring and surface dewpoints have recently surged into the upper 60s. This area will probably have the best chance for a strong tornado in the short term.

Mesoscale Discussion #0626


Concerning...Severe potential...Watch possible 


Valid 022208Z - 022315Z


Probability of Watch Issuance...60 percent


SUMMARY...Storms near a northward lifting warm front has increased in intensity. The environment will be favorable for tornadoes, particularly near the front. A watch is possible for this activity.


DISCUSSION...A cluster of storms developed over the last 60-90 minutes west/southwest of Fort Smith, AR. These storms have been somewhat disorganized. However, as the warm front slowly moves northward, some intensification has been noted. The storm in Le Flore County, OK in particular has taken on a more supercellular structure. With the favorable low-level shear near the warm front -- just north of the boundary, KSRX shows around 400 m2/s2 SRH -- tornado potential is likely increasing for this storm. The main limiting factor will be the storm motion that may take it to the cool side of the boundary relatively quickly.


To the southwest, a differential heating boundary is in place near the Red River. Some guidance shows further development along this boundary. With a similarly favorable supercell environment, tornadoes and large hail would be possible should this occur.

Mesoscale Discussion #0646


Concerning...Tornado Watch 176...177...


Valid 042252Z - 050015Z


The severe weather threat for Tornado Watch 176, 177 continues.


SUMMARY...Storms moving into Northwest Texas and southwest Oklahoma may pose and increasing threat for tornadoes and very large hail as they encounter richer low-level moisture.


DISCUSSION...Ongoing right-moving supercells southwest of Childress, TX has produced 2+ inch hail recently. As this storm moves northeastward, it will reach upper 60s F dewpoints in southwest Oklahoma. Furthermore, it appears that billow clouds in southwest Oklahoma have evolved into more cumuliform over the past couple of hours per visible satellite. This would indicate most inhibition has been eroded. Low-level wind profiles show less turning within the region as compared to central Oklahoma. However, some increase in the low-level jet should promote large effective SRH with time. Tornado potential is expected to increase as storms move into this environment. Very large hail will also be likely with around 2500-3000 J/kg MLCAPE and over 8 C/km mid-level lapse rates.

Mesoscale Discussion #0649


Concerning...Tornado Watch 176...


Valid 050019Z - 050115Z


The severe weather threat for Tornado Watch 176 continues.


SUMMARY...A supercell thunderstorm near the Seminole/Okfuskee County border will continue in a favorable environment for the next 1-2 hours. A local areal extension of WW 176 may be needed.


DISCUSSION...A supercell which has produced tornadoes over the past hour will continue in a favorable environment for the next 1-2 hours as it moves northeast. Inflow air into the storm remains in the mid/upper 70s F with dewpoints having increased by a degree ahead of it (into the upper 60s F). This mature storm should be able to maintain its intensity. A storm to its southwest has also shown increasing organization and tornado potential. Eventually, cooler/drier to the east will lead to a downward trend. A local extension in area of WW 176 may be needed.

Mesoscale Discussion #0650


Concerning...Tornado Watch 177...


Valid 050036Z - 050200Z


The severe weather threat for Tornado Watch 177 continues.


SUMMARY...The greatest tornado potential will continue to exist in Northwest Texas with a supercell moving east just south of Crowell, TX. The downstream environment will remain favorable and low-level winds may improve slightly as well.


DISCUSSION...A strong supercell continues east in Foard County, TX. Tornadoes have been observed with this storm over the last 60-90 minutes. Low-level hodographs are not as enlarged as compared to the east. However, with the unimpeded inflow of upper 70s F temperatures and upper 60s F dewpoints, this storm is expected to maintain intensity as of moves east. As this occurs, it will encounter at least a modestly stronger low-level jet. Tornado and very-large hail potential will continue with this storm.


Another supercell in the southeastern Panhandle continues to show a strong reflectivity signature. Large/very-large hail will remain possible. The tornado potential with this storm should diminish as it will cross north of the warm front into more stable conditions.

Mesoscale Discussion #0651


Concerning...Tornado Watch 176...177...


Valid 050213Z - 050345Z


The severe weather threat for Tornado Watch 176, 177 continues.


SUMMARY...Convective trends suggest that clustering/MCS development may occur over the next few hours along/south of the warm front. Damaging winds will become more common with time. Tornadoes are most likely with discrete storms in Northwest Texas, though line-embedded supercells and circulations are possible as well. Replacement watches will likely be needed this evening.


DISCUSSION...Convective trends in southwestern Oklahoma and Northwest Texas show increasing storm coverage. Supercells are ongoing just south of the Red River, with the lead cell continuing to produced tornadoes. IR satellite trends also indicate cloud cooling along the warm front and NLDN shows an increase in lightning activity. These trends all suggest that MCS development may occur over the next several hours. While temperatures south of the warm front have cooled, low 70s F dewpoints will keep that cooling to a minimum. Given the downstream instability and forcing from the trough, storms should continue along and south of the boundary this evening/overnight. Damaging winds will become more common as a transition away from discrete cells occurs. While some activity will occur north of the warm front, storms there should generally be more of a threat for hail


The greatest short-term tornado threat will continue to be in Northwest Texas with the supercells moving east. Given the low-level wind fields, however, tornadoes will remain possible even with more linear activity.


A replacement tornado watch is likely for activity south of the boundary. The hail threat north of the boundary may be sufficient for a severe thunderstorm watch.

Mesoscale Discussion #0737


Concerning...Severe Thunderstorm Watch 206...


Valid 121942Z - 122145Z


The severe weather threat for Severe Thunderstorm Watch 206 continues.


SUMMARY...The probability for widespread severe wind gusts (including several 75+ mph wind gusts) is increasing across central to northeastern Nebraska. Portions of this area will be be upgraded to a Moderate risk (wind-related).


DISCUSSION...Latest radar imagery from KUEX shows a line of convection rapidly lifting to the north/northeast across southern NE. This activity has produced multiple severe wind reports over the past hour, including an 80 mph wind gust over Dawson county, NE. Recent IR imagery and lightning trends suggest this line is strengthening as MLCIN continues to erode amid strong daytime heating across central/eastern NE (where temperatures are climbing into the low 90s). Further intensification is expected through the afternoon as daytime heating continues to drive boundary-layer mixing and steepening low-level lapse rates ahead of this complex. Furthermore, this line is moving into an environment with increasing MLCAPE (up to 2500-3000 J/kg) and effective bulk shear (near 30-45 knots) per latest RAP mesoanalysis estimates. Consequently, the potential for widespread severe wind (including significant severe winds over 75 mph) is increasing for parts of central to northeastern NE.

Mesoscale Discussion #0738


Concerning...Severe potential...Watch likely 


Valid 121947Z - 122215Z


Probability of Watch Issuance...95 percent


SUMMARY...Severe storms will develop along the fronts in South Dakota later today, and move into eastern South Dakota from the southwest. Widespread damaging winds and several tornadoes are anticipated.


DISCUSSION...Surface analysis shows a cold front approaching central SD and extending into the NE Panhandle. Meanwhile, a warm front extends from near Pierre to south of Aberdeen to Brookings. Visible imagery shows substantial towering CU along and south of this area where temperatures are rising and MLCAPE is over 3000 J/kg. Midlevel lapse rates are very steep, and suggest explosive supercell development will be possible from central into northeast SD. Low-level shear favors tornadoes near the warm front, and a strong tornado will be possible.


To the south, a line of severe storms is quickly taking shape over central NE, and will rapidly move north/northeast across the MO River after 21Z. Significant wind damage will be possible into southeast SD through evening as storms expand into the most unstable air.

Mesoscale Discussion #0739


Concerning...Severe Thunderstorm Watch 208...


Valid 122149Z - 122230Z


CORRECTED FOR TYPO "MONTANA" INSTEAD OF "MINNESOTA"


The severe weather threat for Severe Thunderstorm Watch 208 continues.


SUMMARY...A very intense squall line will bring likely hurricane force winds across portions of southeast South Dakota into southwest Minnesota this evening.


DISCUSSION...A well developed squall line has developed across Nebraska and has already produced multiple wind gusts in the 70 to 90 mph range over the past 1 to 2 hours. This line is moving over 60 knots and is moving into an increasingly favorable environment for severe wind gusts with MLCAPE of 3000 to 4000 J/kg, DCAPE of 1400 J/kg, and effective shear around 50 knots.


All signs point toward a swath of high end wind damage across southeast South Dakota and possibly into southwest Minnesota. Widespread velocities of 90 to 100 knots are being sampled around 4000 feet across Yankton and Bon Homme counties as of 4:30 PM. This is the same region where several consecutive runs of the WoFS have shown a swath with ensemble maximum surface winds of 90 to 100 knots. Therefore, widespread 75+ mph winds are likely with some wind gusts approaching 100 mph possible.

Mesoscale Discussion #0742


Concerning...Tornado Watch 209...


Valid 122223Z - 130030Z


The severe weather threat for Tornado Watch 209 continues.


SUMMARY...The tornado threat is expected to quickly develop across parts of northeastern South Dakota over the next hour. The threat will spread northward with time and increase, especially in the northern and eastern parts of WW 209.


DISCUSSION...The latest radar imagery from Aberdeen, South Dakota shows a severe line segment producing widespread wind damage located across southeastern South Dakota. More discrete cells are developing on the northwestern edge of the line about 50 miles from south to southwest of Aberdeen.  The storms are ongoing in an extremely unstable environment with MLCAPE in the 4000 to 5000 J/kg range. In addition, the Aberdeen WSR-88D VWP has 0-6 km shear near 50 knots with 0-3 km storm relative helicity around 400 m2/s2. This along with a looping hodograph will be favorable for supercells and tornadoes over the next one to two hours. The tornado threat will likely increase due to a strengthening low-level jet as the storms move across northeastern South Dakota. A strong tornado will be possible with any supercell that can become dominant.


The storms will move into southeastern North Dakota and into parts of western Minnesota over the next hour, where a new weather watch will be issued shortly.

Mesoscale Discussion #0746


Concerning...Tornado Watch 211...


Valid 130012Z - 130215Z


The severe weather threat for Tornado Watch 211 continues.


SUMMARY...A wind-damage and tornado threat will continue over the next couple of hours from far northeast South Dakota and southeast North Dakota into west-central and south-central Minnesota.


DISCUSSION...The latest high-resolution radar imagery from Aberdeen shows a severe synoptic-scale bowing line segment located from far northeast South Dakota extending eastward and southward across southwest Minnesota. The line is located to the northeast of a maxima of strong instability, where the RAP is analyzing MLCAPE in the 2500 to 3500 J/kg range. The line of severe storms will continue to move northeastward into a strengthening 50 to 60 knot low-level jet. The jet was creating strong low-level shear, with 0-3 km storm relative helicity at Minneapolis and Aberdeen above 300 m2/s2. This combined with 50 to 60 knots of deep-layer shear will continue to be favorable for severe thunderstorms over the next couple of hours. The low-level jet will continue to increase in strength early this evening, which will support a tornado threat with supercells and bowing line segments. Also, the line was moving northeastward at 65 to 70 knots, which will be very favorable for damaging wind gusts. Isolated wind gusts of over 70 knots will be possible ahead of the more intense portions of the line.

Mesoscale Discussion #1922


Mesoscale Discussion 1922

NWS Storm Prediction Center Norman OK

0717 PM CDT Fri Nov 04 2022


Areas affected...ArkLaTex and southeastern Oklahoma


Concerning...Tornado Watch 560...561...


Valid 050017Z - 050145Z


The severe weather threat for Tornado Watch 560, 561 continues.


SUMMARY...Confirmed dangerous tornadoes are ongoing across portions of the ArkLaTex region. Threat will continue over the next couple of hours.


DISCUSSION...Radar trends continue to show an uptick in intensity of supercells across portions of the ArkLaTex region near the Red River in the last couple of hours. Several confirmed tornadoes have been reported within this region and are continuing. Near this region lies the most favorable overlap of deep layer shear around 40-50+ kts (as observed by VAD profiles at Shreveport and Ft. Smith)  along with storm relative helicity 0-1 km around 300 m2/s2 and MLCAPE around 1000-1500 J/kg slowly nudging north and eastward with time. Objective surface analysis shows a sharp theta-e axis extending into portions of western Louisiana into western Arkansas and eastern Oklahoma. This will continue to be a favored region for more discrete organized supercells and strong tornadoes in the next couple of hours ahead of the cold front.


  ..Thornton/Guyer.. 11/05/2022

Mesoscale Discussion #1978


Mesoscale Discussion 1978

NWS Storm Prediction Center Norman OK

1120 AM CST Tue Nov 29 2022


Areas affected...northern LA...extreme southeast Arkansas and into central MS


Concerning...Severe potential...Tornado Watch likely 


Valid 291720Z - 291945Z


Probability of Watch Issuance...95 percent


SUMMARY...A PDS tornado watch will be needed by 19z/1pm CT for portions of northern Louisiana, extreme southeast Arkansas and into central Mississippi. Tornadoes, a couple potentially long-track and strong, large hail and damaging gusts will be possible into the evening hours.


DISCUSSION...Rich Gulf boundary-layer moisture continues to rapidly return northward across the Lower MS Valley vicinity. Surface dewpoints near 65 F have developed as far north as south-central MS and northern LA late this morning. Meanwhile, the marine warm front, roughly delineating 70 F dewpoints, extends west-to east from southeast TX through central LA into southern MS. Moisture should continue to rapidly increase across northern LA into far southeast AR and MS through the afternoon. A plume of steep midlevel lapse rates will continue to overspread the region, aiding in MLCAPE increasing to 1000-2000 J/kg by mid-afternoon. Breaks in cloud cover across northeast LA into central MS will further aid in destabilization as greater heating occurs within these cloud breaks.


Strong vertical shear, with effective shear magnitudes greater than 45 kt is already in place across the region. Regional VWPs and profilers already show enlarged, favorably curved low-level hodographs with 0-1 km SRH values greater than 250 m2/s. Large-scale ascent will remain modest across the region, resulting in a large warm sector supporting discrete supercells. One or more bands of supercells will be possible within low-level confluence zones. 


A particular dangerous situation is expected to develop across northeast LA into central MS through this evening as multiple supercells track across the area. Tornadoes, a couple strong and long-track, will be possible, in addition to large hail (scattered 2+ inch) and damaging gusts.


   ..Leitman/Hart.. 11/29/2022

Mesoscale Discussion #1984


Mesoscale Discussion 1984

NWS Storm Prediction Center Norman OK

0512 PM CST Tue Nov 29 2022


Areas affected...northern and central Louisiana northeastward to northern Mississippi


Concerning...Tornado Watch 572...


Valid 292312Z - 300045Z


The severe weather threat for Tornado Watch 572 continues.


SUMMARY...Severe-weather risk continues across the WW area, with greatest risk for significant tornadoes evident with supercells crossing northern Louisiana at this time.


DISCUSSION...Latest radar loop shows a broken band of severe/supercell storms extending from near the Sabine River over far eastern Texas, northeastward into northwestern Alabama -- within Tornado Watch 572.  The environment remains quite supportive of ongoing tornado risk, given the moist/unstable and favorably sheared pre-frontal environment.  However, rotation/supercell characteristics with several of the storms have to some degree remained rather transient.  Still, a few longer-lived/sustained supercells continue, and expect additional/more organized evolution over the next couple of hours.


The most substantial of these better-organized rotating cells are moving east-northeastward across northern Louisiana.  One of these, now crossing northern Tensas Parish, should cross the Mississippi River in the Vicksburg vicinity over the next half hour or so.  A second of these longer-lived supercells is crossing southern Winn Parish, while a third has organized over northern Sabine County in East Texas, and will move into Sabine Parish in Louisiana over the next half hour.  All three of the aforementioned storms appear capable of producing tornadoes over the next 1 to 2 hours.  


Finally, a separate/potentially tornadic supercell continues to organize/evolve over southern Jefferson Davis County in Mississippi, well south of the main convective band.  This storm has produced a tornado within the past half hour or so, and will move out of the southeastern portion of Tornado Watch 572 and into newly issued Tornado Watch 574.


   ..Goss.. 11/29/2022

Mesoscale Discussion #2032


Mesoscale Discussion 2032

NWS Storm Prediction Center Norman OK

0120 PM CST Wed Dec 14 2022


Areas affected...Southern MS...Southwest AL...Eastern LA


Concerning...Tornado Watch 588...


Valid 141920Z - 142045Z


The severe weather threat for Tornado Watch 588 continues.


SUMMARY...The threat for strong, long-track tornadoes continues.


DISCUSSION...Regional radar imagery continues to show numerous discrete supercells, including a few which have rotational velocity around 40 to 50 kt. The overall environment remain very conducive to tornadic supercells with ample low-level moisture and buoyancy in the presence of strong low to mid-level flow. Recent KLIX VAD data shows increasing winds in the 1-2 km layer. This increase is likely due to a mesoscale low-level jet, which is expected to move northeastward across far southern MS and into southwest AL over the next several hours. Attendant strengthening of the low-level shear within this corridor could augment the already favorable conditions. Surface observations also numerous gusts of 25 to 30 kt across southeast LA.


Additionally, ongoing storms will likely strengthen as they approach and interact the warm front, which now extends from about 50 miles northwest of MEI southeastward to south of GZH in southern AL.


In all, the threat for strong, long-track tornadoes will continue for at least the next few hours across eastern LA and southern MS, eventually reaching southwest AL later this afternoon/early this evening.


   ..Mosier/Hart.. 12/14/2022