Severe Storms

No Mesoscale Discussions are in effect as of Wed Mar 22 21:25:02 UTC 2023.

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0255 PM CDT Wed Mar 22 2023 Valid 222000Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM CENTRAL/NORTHERN MISSOURI AND SOUTHEAST IOWA INTO NORTHERN/CENTRAL INDIANA... ...SUMMARY... Isolated strong to severe thunderstorms -- capable of large hail -- are possible from central/northern Missouri and southern Iowa eastward to northern Indiana. ...Discussion... Only minor changes were made to the 10-percent thunderstorm probability boundary based on visible satellite trends and calibrated thunderstorm guidance. ..Smith.. 03/22/2023 .PREV DISCUSSION... /ISSUED 1106 AM CDT Wed Mar 22 2023/ ...MO/IA/IL/IN... A cluster of elevated thunderstorms is ongoing across central IL late this morning. This activity will continue eastward into parts of IN/OH through the afternoon on the nose of a modest southwesterly low-level jet and warm advection regime. Weak elevated instability may support small hail in the short term. By late afternoon into this evening, upper 50s to low 60s F surface dewpoints will spread northward into central MO/IL ahead of a southeastward-advancing cold front. As the low-level jet increases to around 40-50 kt, organized thunderstorms are expected to develop across north-central MO into southeast IA and central IL near/after 00z. This activity will likely remain elevated as it spreads eastward across IN into western OH overnight. Nevertheless, effective shear magnitudes around 30-35 kt will support organized convection. Elongated hodographs above 3 km, along with the bulk of instability in the 700-400 mb layer, will support large hail potential with strongest activity this evening/overnight. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0124 PM CDT Wed Mar 22 2023 Valid 231200Z - 241200Z ...NO CRITICAL AREAS... The previous forecast remains on track for no widespread elevated or critical fire-weather conditions on D2/Thursday. Localized elevated fire-weather conditions are possible Thursday afternoon in some portions of the southern High Plains. Strengthening mid-level flow will yield dry, downsloping winds in southeast CO, but the extent of boundary-layer mixing is questionable. Further south in West TX and southeastern NM, the meteorological and fuel factors mentioned in the previous discussion preclude the introduction of an Elevated area at this time. ..Flournoy/Wendt.. 03/22/2023 .PREV DISCUSSION... /ISSUED 0157 AM CDT Wed Mar 22 2023/ ...Synopsis... Southwesterly flow aloft over the southern half of the CONUS will continue to amplify ahead of trough ejecting out of the Desert Southwest D2/Thursday. A lee cyclone initially over eastern CO is forecast to move eastward, supporting gusty winds over the southern and central High Plains. Isolated fire-weather conditions may develop over portions of southwest TX and the southern High Plains, but area fuels remain mostly unfavorable for significant fire-weather concerns. ...Southwest Texas and the southern High Plains... As the lee cyclone moves eastward into Day2/Thursday, a trailing surface pressure trough/weak dryline will pass through portions of southwest TX and the southern High Plains. Behind this boundary, model soundings show deep and well-mixed boundary layers with afternoon RH values in the teens. Coincident with winds of 15-25 mph, a few hours of elevated meteorological conditions appear possible from the TX Big Bend, northwestward into far southeastern NM. However, fuels across this area appear only marginally receptive to fire spread. Area ERC values near or slightly below seasonal averages suggest any fire-weather threat will likely remain local in nature. While meteorological conditions would normally necessitate an categorical upgrade to Elevated, confidence in the coverage of sustained fire-weather concerns remains low, owing to marginal fuels. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1234 PM CDT Wed Mar 22 2023 Valid 231200Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF EASTERN AND SOUTHERN OKLAHOMA INTO PARTS OF CENTRAL TEXAS... ...SUMMARY... Thunderstorms capable of hail, some very large, are possible Thursday afternoon through Friday morning across parts of the southern Great Plains. ...Southern Great Plains into the mid MS Valley... Models show a strong upper jet centered over the Great Lakes and moving to the Northeast during the period. A frontal zone will sag southward across parts of the lower MO Valley and OK during the day before stalling during the late afternoon. Southerly low-level flow will maintain a persistent fetch of a seasonably moisture-rich air across the southern Great Plains, featuring mid 60s dewpoints across north TX and into southern/central OK south of the boundary. Large-scale troughing located over the Desert Southwest will gradually move east and approach the southern High Plains by early Friday morning. Low-level warm-air advection and the front will likely aid in storm development of an initially capped airmass. Models indicate moderate buoyancy developing by mid-late afternoon with MLCAPE ranging from 1000-2000 J/kg from the western part of the Ozark Plateau west-southwestward parts of western north TX. The lack of appreciable cyclogenesis over the Red River Valley will likely play a role in limiting both low-level flow (i.e., low-level shear) and an overall supercell tornado risk. However, strong deep-layer shear will promote updraft organization with the more intense storms and favor a mix mode of supercells and multicellular clusters with time. Large to very large hail is possible with the stronger storms. Additional storms are possible farther south along a dryline over parts of the Edwards Plateau during the evening. Upscale growth into one or more convective bands with some lingering severe risk will be possible into the overnight hours as the activity moves east/southeast to near the north TX I-35 corridor. Farther northeast over MO/IL, weaker buoyancy is progged by model guidance. Scattered thunderstorms are forecast to develop near and north of the front during the evening. A couple of stronger storms could yield an isolated risk for large hail before convective overturning occurs. ...Southern Great Lakes... Elevated thunderstorms will likely be ongoing near a weak surface low across northern IL/northern IN early Thursday morning. Weak buoyancy on the northeast periphery of steeper mid-level lapse rates may result in a stronger storm or two during the morning. However, the coverage/magnitude of a hail threat precludes low-severe probabilities. ..Smith.. 03/22/2023 Read more

No watches are valid as of Tue Mar 21 21:12:02 UTC 2023.

MD 0306 CONCERNING HEAVY SNOW FOR NORTHEAST SOUTH DAKOTA...SOUTHEAST NORTH DAKOTA...AND WEST-CENTRAL MINNESOTA.
Mesoscale Discussion 0306 NWS Storm Prediction Center Norman OK 0357 PM CDT Tue Mar 21 2023 Areas affected...Northeast South Dakota...southeast North Dakota...and west-central Minnesota. Concerning...Heavy snow Valid 212057Z - 220100Z SUMMARY...An area of moderate to heavy snow is expanding across the northern Plains this afternoon/evening. DISCUSSION...Afternoon water vapor imagery shows a shortwave trough moving out of northeast Wyoming and into western South Dakota. Low-level southerly flow has strengthened ahead of this trough with 1km flow increasing from ~15 knots to ~35 kts on the KABR VWP over the past 3-4 hours. As a result, moderate to locally heavy snowfall has expanded across northeast South Dakota this afternoon with heavy snow reported at Aberdeen at 20Z. Expect this area of moderate to heavy snow to increase north-northeastward this evening as isentropic ascent strengthens and a weak surface low develops. Initially, expect heavy snow and 1+ inch per hour snowfall rates to remain isolated with more widespread 1 to 1.5 inch per hour snowfall rates starting between 23-00Z across southeast North Dakota as the system strengthens. ..Bentley/Leitman.. 03/21/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...FGF...ABR...BIS... LAT...LON 45589993 46899911 47169628 46439564 45219763 45319894 45589993 Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0226 PM CDT Tue Mar 21 2023 Valid 212000Z - 221200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected today through tonight. ...Synopsis... The probability for severe thunderstorms remains too low for risk probabilities. Latest GOES and radar imagery shows building cumulus and deepening convection across central CA ahead of the approaching upper low. Sporadic lightning strikes and convection-driven wind gusts up to 50 mph have been noted within the past few hours, and will remain possible through the evening hours as cooling aloft continues to steepen lapse rates. While small hail and strong wind gusts remain possible, the transient nature of deeper convective towers over the past couple of hours, coupled with poor signals for severe convection in recent hi-res guidance, continues to suggest the overall severe threat remains limited. ..Moore/Smith.. 03/21/2023 .PREV DISCUSSION... /ISSUED 1107 AM CDT Tue Mar 21 2023/ ...Discussion... An upper low and attendant trough will continue to shift east across central CA toward the western Great Basin through the period. Strong west/southwest deep-layer flow on the south side of this system will extend from southern CA through the Four Corners. Abundant moisture and cooling aloft, resulting in steep midlevel lapse rates, will support areas of 100-400 J/kg MLCAPE across parts of coastal southern/central CA into the southern Sacramento and San Joaquin Valleys. Isolated thunderstorms will be possible through the period. Sufficient effective shear, with some modest vertically veering wind profiles and small, but favorably curved low-level hodographs, could support a brief/transient supercell or two this afternoon/evening. Small hail and gusty winds would be the main hazards with any stronger convection. However, the risk is expected to remain too conditional and limited in coverage/longevity to include marginal probabilities. Further east, increasing westerly deep-layer flow will overspread the Plains and the Midwest as a series of weak shortwave impulses traverse the region. Low-level warm advection will bring mainly upper 40s to 50s F surface dewpoints as far north as central/eastern KS and eastward into the Lower MS Valley through tonight. Steepening midlevel lapse rates atop an EML around 850 mb will contribute to modest elevated instability (200-500 J/kg MUCAPE). Isolated, elevated thunderstorms will be possible across the Mid-MS Valley vicinity on the nose of stronger warm advection. Severe potential appears limited, but any stronger cells that develop across northern MO near the end of the period could perhaps produce small hail. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0151 PM CDT Tue Mar 21 2023 Valid 221200Z - 231200Z The previous discussion remains on track with elevated to locally critical fire-weather conditions expected on Wednesday afternoon in portions of the Central and Southern High Plains. ...High Plains... Latest guidance continues to suggest that widespread elevated fire-weather conditions will materialize in southeastern CO and the OK/TX Panhandles on Wednesday. An ejecting mid-level wave and associated surface cyclone development will generate broad, gusty and dry conditions. Locally critical conditions might develop in the afternoon, but uncertainties regarding mid-/upper-level cloud cover and how low relative humidities will get preclude the introduction of a Critical area in this outlook. To the south, latest guidance suggests that locally elevated conditions may develop Thursday afternoon in the Caprock. Dry and windy conditions are anticipated, but fuel moisture tends to increase with southward extent. The Elevated area has been extended slightly to the south to reflect these factors. ..Flournoy/Wendt.. 03/21/2023 .PREV DISCUSSION... /ISSUED 0154 AM CDT Tue Mar 21 2023/ ...Synopsis... Southwesterly flow aloft is forecast to amplify further D2/Wednesday ahead of a shortwave trough ejecting eastward. In response to the approach of the trough, lee cyclogenesis will intensify over the southern and central High Plains. Gusty winds and low humidity are expected over the higher terrain, with a risk for elevated to locally critical fire-weather conditions. ...Southern and central High Plains... As the surface lee low deepens, gusty southwesterly winds are expected to develop off the higher terrain across portions of northeastern NM/southern CO, into the OK/TX Panhandles. Surface temperatures in the 70s F, along with mechanical mixing from the strong flow aloft, will allow afternoon RH vales to fall below 20%. Coincident with surface wind gusts of 20-25 kt, widespread Elevated fire-weather conditions are likely within modestly receptive fuels over portions of the southern and central High Plains. Locally critical conditions may also develop with terrain-enhanced winds (gusts 30+ kt) farther north across southeastern CO. However, confidence in critical humidity values there is low, suggesting critical fire-weather conditions may remain more localized in nature. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1211 PM CDT Tue Mar 21 2023 Valid 221200Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM NORTHEAST KANSAS INTO NORTHEAST ILLINOIS AND NORTHWEST INDIANA... ...SUMMARY... Isolated strong to severe thunderstorms capable of large hail are possible from far northeast Kansas across northern Missouri and into the lower Lake Michigan region late Wednesday evening into early Thursday morning. ...Synopsis... An upper wave approaching the southern CA coast is forecast to deepen over the next 24-48 hours across the southwestern CONUS. As this occurs, strengthening zonal flow over the central Rockies will foster the development of a weak lee cyclone over the central Plains by Wednesday afternoon. This low will aid in northward advection of upper 50s/low 60s dewpoints into the lower Missouri River Valley as it moves to the northeast along a diffuse stationary frontal zone left in the wake of a leading shortwave trough across the upper MS Valley/Lake Superior region. The combination of gradually improving low-level moisture and steepening mid-level lapse rates will bolster buoyancy along the frontal zone with MUCAPE as high as 1000-1500 J/kg by late evening across northern MO into central IL. Strengthening flow aloft ahead of the deepening synoptic wave to the west will elongate hodographs and support effective bulk shear values in excess of 40 knots during the overnight hours. Convective initiation appears most likely during the 00-03 UTC period across northern MO/western IL within a warm advection regime ahead of the migratory surface low. Initially discrete storms are expected to gradually grow upscale into clusters given mean flow and deep-layer shear vectors generally oriented along the frontal zone. However, the thermodynamic/kinematic environment should support some degree of storm organization, including the potential for a few elevated supercells capable of large hail and perhaps a strong gust or two. Confidence in the severe threat decreases with eastern extent into IN/lower MI where weaker mid-level lapse rates are expected, but a mature storm or two may migrate into this region during the early morning hours Thursday given the favorable kinematic environment. ..Moore/Smith.. 03/21/2023 Read more

No watches are valid as of Mon Mar 20 21:22:01 UTC 2023.

No Mesoscale Discussions are in effect as of Mon Mar 20 21:22:01 UTC 2023.

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0240 PM CDT Mon Mar 20 2023 Valid 202000Z - 211200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected today. No changes were required to the previous outlook. ..Jewell.. 03/20/2023 .PREV DISCUSSION... /ISSUED 1103 AM CDT Mon Mar 20 2023/ ...Synopsis... A midlevel shortwave impulse will continue to shift east across the Great Basin toward the central Rockies today/tonight. Midlevel moisture, and cool temperatures aloft, combined with steep lapse rates will support 100-300 J/kg MUCAPE. Isolated lightning flashes will continue through the forecast period, especially across southeast ID, UT and western CO. Very modest effective shear, and generally cool and dry low-levels will preclude severe potential. Late tonight, low-level warm advection is forecast across the southern Plains vicinity as weak cyclogenesis occurs over eastern CO in response to the approaching western CONUS shortwave trough. Boundary-layer moisture will remain modest, but increasing midlevel moisture, and steepening lapse rates should be sufficient for developing weak elevated instability through the -12 to -25 C layer. As such, a few lightning flashes are possible across parts of OK/KS after 06z tonight. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0107 PM CDT Mon Mar 20 2023 Valid 211200Z - 221200Z ...NO CRITICAL AREAS... No changes to the ongoing forecast. ..Wendt.. 03/20/2023 .PREV DISCUSSION... /ISSUED 0151 AM CDT Mon Mar 20 2023/ ...Synopsis... Zonal flow aloft will trend more southwesterly with time over portions of the southern and central Rockies ahead of a deepening mid-level trough over the Desert Southwest. While not overly strong, a persistent lee cyclone should support gusty surface winds across much of the southern and central High Plains D2/Tuesday. Localized fire-weather potential may develop to the southwest of the surface low over portions of the southern High Plains. ...Southern High Plains... Broad southerly flow ahead of the surface low should gradually veer to southwesterly through the day across portions of the southern High Plains. Downslope trajectories and increased mixing from strengthening flow aloft ahead of the upper trough will favor some drying of the surface airmass. While to the east, returning Gulf moisture should keep humidity values above criteria, isolated pockets below 25% are possible across the TX/OK Panhandles and northeastern NM Tuesday afternoon. Wind gusts to near 20 kt may briefly overlap with the lower relative humidity, supporting a risk for some fire-weather concerns. However, uncertainty on the spatial and temporal overlap of dry and windy conditions remains high, suggesting the fire-weather threat will remain localized. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1138 AM CDT Mon Mar 20 2023 Valid 211200Z - 221200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected on Tuesday. ...Synopsis... On Tuesday, an upper low will move into central CA with a strong cyclonically-curved midlevel jet nosing into AZ and UT by 12Z Wednesday. Generally zonal flow conditions will prevail across the central and eastern states with high pressure over the East. Cold air aloft across the West will lead to areas of daytime thunderstorms from central and southern CA into the Great Basin. Weak instability is expected to preclude any severe storm threat. While the primary surface low will affect central CA and NV, a secondary low will develop over KS, with increasing low-level moisture return occurring from TX into OK. A leading/weaker wave and associated low-level jet will aid scattered elevated thunderstorms mainly from eastern KS into MO, but instability will be too weak for severe storms. Otherwise, the remainder of the warm sector across the southern Plains is to remain stable due to temporary warming aloft. ..Jewell.. 03/20/2023 Read more

No watches are valid as of Sun Mar 19 21:14:02 UTC 2023.

No Mesoscale Discussions are in effect as of Sun Mar 19 21:14:02 UTC 2023.

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0201 PM CDT Sun Mar 19 2023 Valid 192000Z - 201200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected today. No changes were made to the previous outlook with minimal thunderstorm chances across the CONUS. Isolated lightning flashes remain possible with activity near the FL Straits and perhaps into the Sierra where lift is maximized with minimal MUCAPE. ..Jewell.. 03/19/2023 .PREV DISCUSSION... /ISSUED 1109 AM CDT Sun Mar 19 2023/ ...Synopsis... A mid-level trough will progress across the eastern CONUS as a second upper trough impinges on the West Coast today. Surface high pressure and associated subsidence and cooler temperatures will limit thunderstorm development across most of the CONUS through 12Z Monday. On exception would be offshore areas just south of the FL Keys, where a southward-sagging cold front continues to support few ongoing thunderstorms which are expected to gradually drift away from FL through the day. Another area that may see a couple of lightning flashes would be the higher terrain of the Sierra, where orographic ascent of deep low-level moisture and scant buoyancy may support convective snow potential through the period. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0114 PM CDT Sun Mar 19 2023 Valid 201200Z - 211200Z ...NO CRITICAL AREAS... No changes to the ongoing forecast. ..Wendt.. 03/19/2023 .PREV DISCUSSION... /ISSUED 0153 AM CDT Sun Mar 19 2023/ ...Synopsis... Broad mid-level zonal flow is expected over much of the CONUS as the overall upper-air pattern deamplifys in the wake of the departing East Coast upper low. Transient ridging over the central US should weaken, allowing an area of high pressure at the surface to also weaken as it shifts eastward. Westerly flow over the Rockies will support increased lee troughing and dry southerly return flow across much of the Plains. ...Southern Plains... As surface high pressure over the central US weakens and shifts eastward, southerly return flow over much of the southern and central Plains is expected to develop on it westward flank. Aided by a deepening lee trough/developing surface cyclone, gusty southerly winds of 20-25 mph are possible. While not overly warm, the dry airmass will support afternoon RH values below 25% at times. The combination of gusty winds and lower relative humidity may support localized pockets of elevated fire-weather conditions through the afternoon. Primary uncertainty remains fuel availability and the duration of overlap with the dry/breezy conditions. For now, confidence in sustained fire-weather conditions remains too low for an Elevated area. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1214 PM CDT Sun Mar 19 2023 Valid 201200Z - 211200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected Monday. ...Synopsis... A large area of high pressure will encompass much of the central and eastern CONUS on Monday as an upper trough moves toward the East Coast. Behind this system, moderate west/northwest flow aloft will exist in the southern stream from southern CA into the Gulf of Mexico. Cool midlevel temperatures will exist over the Great Basin north of the jet axis, with daytime heating resulting in scattered weak thunderstorms. To the east, low pressure is forecast to develop over the central Plains overnight and into Tuesday morning, with a strong low-level jet response as the nose of the upper jet moves into the area. The result may be up to 100 J/kg of MUCAPE centered over parts of KS, and a few lightning flashes may result. ..Jewell.. 03/19/2023 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1128 AM CDT Sun Mar 19 2023 Valid 191700Z - 201200Z ...NO CRITICAL AREAS... No changes to the ongoing forecast. ..Wendt.. 03/19/2023 .PREV DISCUSSION... /ISSUED 0151 AM CDT Sun Mar 19 2023/ ...Synopsis... In the mid levels, a broad cyclone over the East Coast will continue offshore with strong northwesterly flow in its wake across the eastern third of the CONUS. At the same time, mostly zonal flow will develop over the central CONUS. Stronger flow aloft will develop farther west ahead of a low-amplitude trough moving onshore across the West Coast. Much of the CONUS will remain post frontal at the surface, with relatively cool and stable conditions expected beneath a broad area of high pressure. However, as the high shifts south and east through the day, lee troughing will begin to support drier and windier conditions across portions of the southern High Plains this afternoon. ...Southern and central High Plains... On the fringes of the remnant post-frontal airmass across the central CONUS, gusty downslope winds and increasingly dry air are possible over portions of the High Plains. As the airmass is modified this afternoon, surface winds greater than 20 kt may overlap with afternoon RH values near or below 20% for a few hours across portions of northeastern NM, portions of eastern CO, and western KS. While some locally elevated meteorological conditions are possible, fuel conditions remains somewhat marginal given the recent freeze. The poor overlap of dry/windy conditions with receptive fuels suggests the fire-weather threat will remain localized this afternoon. However, should more widespread and longer duration fire-weather conditions appear more likely, a small Elevated area may be introduced in subsequent outlooks. ...Eastern US... Breezy offshore winds are possible today in the wake of the departing upper low off the East Coast. While somewhat drier than normal, winds are not expected to gust more than 15-20 mph with cool temperatures and RH values remaining near or above 30%. A few hours of locally elevated fire-weather conditions may develop over areas of drier than average fuels, but widespread fire-weather concerns are not anticipated. ...Please see www.spc.noaa.gov/fire for graphic product... Read more