Severe Storms

MD 0866 CONCERNING SEVERE THUNDERSTORM WATCH 274... FOR SOUTHEASTERN NEBRASKA
Mesoscale Discussion 0866 NWS Storm Prediction Center Norman OK 0408 AM CDT Tue May 21 2024 Areas affected...southeastern Nebraska Concerning...Severe Thunderstorm Watch 274... Valid 210908Z - 211115Z The severe weather threat for Severe Thunderstorm Watch 274 continues. SUMMARY...Local severe risk continues across the southeastern quarter of Nebraska. DISCUSSION...Thunderstorms continue across a sizable portion of southeastern Nebraska at this time, with the strongest convection in a roughly north-south band crossing the Howard/Hall/Kearney/Franklin County vicinity. This convection is ongoing either side of the primary surface baroclinic zone, near the nose of a 60-kt south-southwesterly low-level jet. Downstream from this eastward-moving band of storms, around 1500 J/kg mixed-layer CAPE is indicated by RAP-based objective analysis on the warm side of the front. This -- along with lift provided by the surface front and aforementioned low-level jet -- should allow storms to persist over the next couple of hours, with a couple of wind gusts to near severe levels still possible, along with marginal hail. ..Goss.. 05/21/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...OAX...GID... LAT...LON 39909896 40599885 41449792 42059632 41079567 40409581 39909896 Read more

WW 0274 Status Updates
STATUS REPORT ON WW 274 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 40 WSW BIE TO 10 E OLU TO 10 WNW OFK. ..GOSS..05/21/24 ATTN...WFO...OAX...GID...LBF... STATUS REPORT FOR WS 274 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS IAC085-129-133-155-165-211140- IA . IOWA COUNTIES INCLUDED ARE HARRISON MILLS MONONA POTTAWATTAMIE SHELBY NEC021-023-025-037-039-053-055-067-095-097-109-119-131-139-151- 153-155-159-167-173-177-179-211140- NE . NEBRASKA COUNTIES INCLUDED ARE BURT BUTLER CASS COLFAX CUMING DODGE DOUGLAS GAGE JEFFERSON JOHNSON LANCASTER MADISON OTOE PIERCE SALINE SARPY SAUNDERS SEWARD STANTON THURSTON WASHINGTON WAYNE Read more

WW 0274 Status Updates
STATUS REPORT ON WW 274 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 40 WSW BIE TO 10 E OLU TO 10 WNW OFK. ..GOSS..05/21/24 ATTN...WFO...OAX...GID...LBF... STATUS REPORT FOR WS 274 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS IAC085-129-133-155-165-211140- IA . IOWA COUNTIES INCLUDED ARE HARRISON MILLS MONONA POTTAWATTAMIE SHELBY NEC021-023-025-037-039-053-055-067-095-097-109-119-131-139-151- 153-155-159-167-173-177-179-211140- NE . NEBRASKA COUNTIES INCLUDED ARE BURT BUTLER CASS COLFAX CUMING DODGE DOUGLAS GAGE JEFFERSON JOHNSON LANCASTER MADISON OTOE PIERCE SALINE SARPY SAUNDERS SEWARD STANTON THURSTON WASHINGTON WAYNE Read more

WW 0274 Status Updates
STATUS REPORT ON WW 274 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 40 WSW BIE TO 10 E OLU TO 10 WNW OFK. ..GOSS..05/21/24 ATTN...WFO...OAX...GID...LBF... STATUS REPORT FOR WS 274 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS IAC085-129-133-155-165-211140- IA . IOWA COUNTIES INCLUDED ARE HARRISON MILLS MONONA POTTAWATTAMIE SHELBY NEC021-023-025-037-039-053-055-067-095-097-109-119-131-139-151- 153-155-159-167-173-177-179-211140- NE . NEBRASKA COUNTIES INCLUDED ARE BURT BUTLER CASS COLFAX CUMING DODGE DOUGLAS GAGE JEFFERSON JOHNSON LANCASTER MADISON OTOE PIERCE SALINE SARPY SAUNDERS SEWARD STANTON THURSTON WASHINGTON WAYNE Read more

WW 0274 Status Updates
STATUS REPORT ON WW 274 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 40 WSW BIE TO 10 E OLU TO 10 WNW OFK. ..GOSS..05/21/24 ATTN...WFO...OAX...GID...LBF... STATUS REPORT FOR WS 274 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS IAC085-129-133-155-165-211140- IA . IOWA COUNTIES INCLUDED ARE HARRISON MILLS MONONA POTTAWATTAMIE SHELBY NEC021-023-025-037-039-053-055-067-095-097-109-119-131-139-151- 153-155-159-167-173-177-179-211140- NE . NEBRASKA COUNTIES INCLUDED ARE BURT BUTLER CASS COLFAX CUMING DODGE DOUGLAS GAGE JEFFERSON JOHNSON LANCASTER MADISON OTOE PIERCE SALINE SARPY SAUNDERS SEWARD STANTON THURSTON WASHINGTON WAYNE Read more

WW 0274 Status Updates
STATUS REPORT ON WW 274 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 40 WSW BIE TO 10 E OLU TO 10 WNW OFK. ..GOSS..05/21/24 ATTN...WFO...OAX...GID...LBF... STATUS REPORT FOR WS 274 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS IAC085-129-133-155-165-211140- IA . IOWA COUNTIES INCLUDED ARE HARRISON MILLS MONONA POTTAWATTAMIE SHELBY NEC021-023-025-037-039-053-055-067-095-097-109-119-131-139-151- 153-155-159-167-173-177-179-211140- NE . NEBRASKA COUNTIES INCLUDED ARE BURT BUTLER CASS COLFAX CUMING DODGE DOUGLAS GAGE JEFFERSON JOHNSON LANCASTER MADISON OTOE PIERCE SALINE SARPY SAUNDERS SEWARD STANTON THURSTON WASHINGTON WAYNE Read more

WW 274 SEVERE TSTM IA KS NE 210430Z - 211200Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 274 NWS Storm Prediction Center Norman OK 1130 PM CDT Mon May 20 2024 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Extreme western Iowa Extreme north central Kansas Central into eastern Nebraska * Effective this Monday night and Tuesday morning from 1130 PM until 700 AM CDT. * Primary threats include... Widespread damaging winds and isolated significant gusts to 75 mph likely Scattered large hail events to 1.5 inches in diameter likely A tornado or two possible SUMMARY...Ongoing storms with a hail/wind threat may persist for a couple more hours across eastern Nebraska/western Iowa, while storms well to the west will grow upscale into a larger/bowing convective system overnight into central then eastern Nebraska. Damaging wind swaths up to 75 mph will be the main threat, along with large hail up to 1.5 inches in diameter and a tornado or two with embedded circulations. The severe thunderstorm watch area is approximately along and 65 statute miles north and south of a line from 60 miles south southwest of Broken Bow NE to 20 miles northeast of Omaha NE. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU4). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. && OTHER WATCH INFORMATION...This severe thunderstorm watch replaces severe thunderstorm watch number 271. Watch number 271 will not be in effect after 1130 PM CDT. CONTINUE...WW 269...WW 272...WW 273... AVIATION...A few severe thunderstorms with hail surface and aloft to 1.5 inches. Extreme turbulence and surface wind gusts to 65 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 25035. ...Thompson Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0404 AM CDT Tue May 21 2024 Valid 241200Z - 291200Z ...DISCUSSION... ...Day 4/Fri - Mid MS Valley/Upper Great Lakes vicinity... An upper shortwave trough over the northern Plains will pivot northeast across the Upper Midwest on Friday. At the surface, low pressure will develop northward across MN/WI and a trailing cold front will push east, becoming positioned from WI to central OK/MO by Saturday morning. Some severe potential is possible ahead of the front from the Mid-MS Valley into the Great Lakes vicinity. However, ongoing convection early Friday and large-scale ascent lifting northeast of the region with time is resulting in uncertainty. Severe probabilities will likely be needed in subsequent outlooks as mesoscale details become better resolved, but confidence is too low to delineate an unconditional 15 percent probability at this time. ...Day 5/Sat - Southern Plains to the Ozarks vicinity... Low-amplitude west/southwest mid/upper flow is forecast across the southern Plains to the Mid-South vicinity for much of the diurnal period on Saturday. By 00z, forecast guidance suggests a shortwave trough will eject from the southern Rockies into the southern Plains, and eventually impinging on the Ozarks/Mid-South area by Sunday morning. A very moist and unstable airmass is forecast over the southern Plains vicinity ahead of this feature as a surface warm front lifts northward through the day. Increasing ascent may not arrive until after 00-03z, limiting convective initiation until the nighttime hours. If storms can develop during the day across portions of OK/TX, all hazards severe potential will exist. Otherwise, thunderstorm potential may be more likely during the evening/overnight from north TX into southeast OK and AR as large-scale ascent increases and a 65-75 kt 500 mb jet overspreads the region. The north and west bounds of severe potential are a bit uncertain, so this area may shift in subsequent outlooks. ...Day 6/Sun - Ozarks to the Lower OH and TN Valleys... An upper shortwave trough will progress across the region on Sunday. Forecast guidance depicts a 50-60 kt southwesterly 700 mb jet overspreading the region during the day. Meanwhile, a surface low will intensify over MO/IL, shifting northeast along the OH River through the period. A very moist and unstable airmass is depicted ahead of the low and attendant south/southeastward-progressing cold front. Intense severe thunderstorms will likely accompany this system. Consistency among deterministic guidance, favorable synoptic pattern, as well as CSU/NSSL ML output, support introduction of 15 percent probabilities for Sunday. ...Days 7-8/Mon-Tue... Spread among forecast guidance increases substantially by the end of the forecast period. However, a pattern shift by Day 8/Tue appears possible, with an amplified upper ridge potentially building over the western half of the CONUS. Overall, predictability is too low to delineate areas of severe potential across the eastern half of the CONUS. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0404 AM CDT Tue May 21 2024 Valid 241200Z - 291200Z ...DISCUSSION... ...Day 4/Fri - Mid MS Valley/Upper Great Lakes vicinity... An upper shortwave trough over the northern Plains will pivot northeast across the Upper Midwest on Friday. At the surface, low pressure will develop northward across MN/WI and a trailing cold front will push east, becoming positioned from WI to central OK/MO by Saturday morning. Some severe potential is possible ahead of the front from the Mid-MS Valley into the Great Lakes vicinity. However, ongoing convection early Friday and large-scale ascent lifting northeast of the region with time is resulting in uncertainty. Severe probabilities will likely be needed in subsequent outlooks as mesoscale details become better resolved, but confidence is too low to delineate an unconditional 15 percent probability at this time. ...Day 5/Sat - Southern Plains to the Ozarks vicinity... Low-amplitude west/southwest mid/upper flow is forecast across the southern Plains to the Mid-South vicinity for much of the diurnal period on Saturday. By 00z, forecast guidance suggests a shortwave trough will eject from the southern Rockies into the southern Plains, and eventually impinging on the Ozarks/Mid-South area by Sunday morning. A very moist and unstable airmass is forecast over the southern Plains vicinity ahead of this feature as a surface warm front lifts northward through the day. Increasing ascent may not arrive until after 00-03z, limiting convective initiation until the nighttime hours. If storms can develop during the day across portions of OK/TX, all hazards severe potential will exist. Otherwise, thunderstorm potential may be more likely during the evening/overnight from north TX into southeast OK and AR as large-scale ascent increases and a 65-75 kt 500 mb jet overspreads the region. The north and west bounds of severe potential are a bit uncertain, so this area may shift in subsequent outlooks. ...Day 6/Sun - Ozarks to the Lower OH and TN Valleys... An upper shortwave trough will progress across the region on Sunday. Forecast guidance depicts a 50-60 kt southwesterly 700 mb jet overspreading the region during the day. Meanwhile, a surface low will intensify over MO/IL, shifting northeast along the OH River through the period. A very moist and unstable airmass is depicted ahead of the low and attendant south/southeastward-progressing cold front. Intense severe thunderstorms will likely accompany this system. Consistency among deterministic guidance, favorable synoptic pattern, as well as CSU/NSSL ML output, support introduction of 15 percent probabilities for Sunday. ...Days 7-8/Mon-Tue... Spread among forecast guidance increases substantially by the end of the forecast period. However, a pattern shift by Day 8/Tue appears possible, with an amplified upper ridge potentially building over the western half of the CONUS. Overall, predictability is too low to delineate areas of severe potential across the eastern half of the CONUS. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0404 AM CDT Tue May 21 2024 Valid 241200Z - 291200Z ...DISCUSSION... ...Day 4/Fri - Mid MS Valley/Upper Great Lakes vicinity... An upper shortwave trough over the northern Plains will pivot northeast across the Upper Midwest on Friday. At the surface, low pressure will develop northward across MN/WI and a trailing cold front will push east, becoming positioned from WI to central OK/MO by Saturday morning. Some severe potential is possible ahead of the front from the Mid-MS Valley into the Great Lakes vicinity. However, ongoing convection early Friday and large-scale ascent lifting northeast of the region with time is resulting in uncertainty. Severe probabilities will likely be needed in subsequent outlooks as mesoscale details become better resolved, but confidence is too low to delineate an unconditional 15 percent probability at this time. ...Day 5/Sat - Southern Plains to the Ozarks vicinity... Low-amplitude west/southwest mid/upper flow is forecast across the southern Plains to the Mid-South vicinity for much of the diurnal period on Saturday. By 00z, forecast guidance suggests a shortwave trough will eject from the southern Rockies into the southern Plains, and eventually impinging on the Ozarks/Mid-South area by Sunday morning. A very moist and unstable airmass is forecast over the southern Plains vicinity ahead of this feature as a surface warm front lifts northward through the day. Increasing ascent may not arrive until after 00-03z, limiting convective initiation until the nighttime hours. If storms can develop during the day across portions of OK/TX, all hazards severe potential will exist. Otherwise, thunderstorm potential may be more likely during the evening/overnight from north TX into southeast OK and AR as large-scale ascent increases and a 65-75 kt 500 mb jet overspreads the region. The north and west bounds of severe potential are a bit uncertain, so this area may shift in subsequent outlooks. ...Day 6/Sun - Ozarks to the Lower OH and TN Valleys... An upper shortwave trough will progress across the region on Sunday. Forecast guidance depicts a 50-60 kt southwesterly 700 mb jet overspreading the region during the day. Meanwhile, a surface low will intensify over MO/IL, shifting northeast along the OH River through the period. A very moist and unstable airmass is depicted ahead of the low and attendant south/southeastward-progressing cold front. Intense severe thunderstorms will likely accompany this system. Consistency among deterministic guidance, favorable synoptic pattern, as well as CSU/NSSL ML output, support introduction of 15 percent probabilities for Sunday. ...Days 7-8/Mon-Tue... Spread among forecast guidance increases substantially by the end of the forecast period. However, a pattern shift by Day 8/Tue appears possible, with an amplified upper ridge potentially building over the western half of the CONUS. Overall, predictability is too low to delineate areas of severe potential across the eastern half of the CONUS. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0404 AM CDT Tue May 21 2024 Valid 241200Z - 291200Z ...DISCUSSION... ...Day 4/Fri - Mid MS Valley/Upper Great Lakes vicinity... An upper shortwave trough over the northern Plains will pivot northeast across the Upper Midwest on Friday. At the surface, low pressure will develop northward across MN/WI and a trailing cold front will push east, becoming positioned from WI to central OK/MO by Saturday morning. Some severe potential is possible ahead of the front from the Mid-MS Valley into the Great Lakes vicinity. However, ongoing convection early Friday and large-scale ascent lifting northeast of the region with time is resulting in uncertainty. Severe probabilities will likely be needed in subsequent outlooks as mesoscale details become better resolved, but confidence is too low to delineate an unconditional 15 percent probability at this time. ...Day 5/Sat - Southern Plains to the Ozarks vicinity... Low-amplitude west/southwest mid/upper flow is forecast across the southern Plains to the Mid-South vicinity for much of the diurnal period on Saturday. By 00z, forecast guidance suggests a shortwave trough will eject from the southern Rockies into the southern Plains, and eventually impinging on the Ozarks/Mid-South area by Sunday morning. A very moist and unstable airmass is forecast over the southern Plains vicinity ahead of this feature as a surface warm front lifts northward through the day. Increasing ascent may not arrive until after 00-03z, limiting convective initiation until the nighttime hours. If storms can develop during the day across portions of OK/TX, all hazards severe potential will exist. Otherwise, thunderstorm potential may be more likely during the evening/overnight from north TX into southeast OK and AR as large-scale ascent increases and a 65-75 kt 500 mb jet overspreads the region. The north and west bounds of severe potential are a bit uncertain, so this area may shift in subsequent outlooks. ...Day 6/Sun - Ozarks to the Lower OH and TN Valleys... An upper shortwave trough will progress across the region on Sunday. Forecast guidance depicts a 50-60 kt southwesterly 700 mb jet overspreading the region during the day. Meanwhile, a surface low will intensify over MO/IL, shifting northeast along the OH River through the period. A very moist and unstable airmass is depicted ahead of the low and attendant south/southeastward-progressing cold front. Intense severe thunderstorms will likely accompany this system. Consistency among deterministic guidance, favorable synoptic pattern, as well as CSU/NSSL ML output, support introduction of 15 percent probabilities for Sunday. ...Days 7-8/Mon-Tue... Spread among forecast guidance increases substantially by the end of the forecast period. However, a pattern shift by Day 8/Tue appears possible, with an amplified upper ridge potentially building over the western half of the CONUS. Overall, predictability is too low to delineate areas of severe potential across the eastern half of the CONUS. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0404 AM CDT Tue May 21 2024 Valid 241200Z - 291200Z ...DISCUSSION... ...Day 4/Fri - Mid MS Valley/Upper Great Lakes vicinity... An upper shortwave trough over the northern Plains will pivot northeast across the Upper Midwest on Friday. At the surface, low pressure will develop northward across MN/WI and a trailing cold front will push east, becoming positioned from WI to central OK/MO by Saturday morning. Some severe potential is possible ahead of the front from the Mid-MS Valley into the Great Lakes vicinity. However, ongoing convection early Friday and large-scale ascent lifting northeast of the region with time is resulting in uncertainty. Severe probabilities will likely be needed in subsequent outlooks as mesoscale details become better resolved, but confidence is too low to delineate an unconditional 15 percent probability at this time. ...Day 5/Sat - Southern Plains to the Ozarks vicinity... Low-amplitude west/southwest mid/upper flow is forecast across the southern Plains to the Mid-South vicinity for much of the diurnal period on Saturday. By 00z, forecast guidance suggests a shortwave trough will eject from the southern Rockies into the southern Plains, and eventually impinging on the Ozarks/Mid-South area by Sunday morning. A very moist and unstable airmass is forecast over the southern Plains vicinity ahead of this feature as a surface warm front lifts northward through the day. Increasing ascent may not arrive until after 00-03z, limiting convective initiation until the nighttime hours. If storms can develop during the day across portions of OK/TX, all hazards severe potential will exist. Otherwise, thunderstorm potential may be more likely during the evening/overnight from north TX into southeast OK and AR as large-scale ascent increases and a 65-75 kt 500 mb jet overspreads the region. The north and west bounds of severe potential are a bit uncertain, so this area may shift in subsequent outlooks. ...Day 6/Sun - Ozarks to the Lower OH and TN Valleys... An upper shortwave trough will progress across the region on Sunday. Forecast guidance depicts a 50-60 kt southwesterly 700 mb jet overspreading the region during the day. Meanwhile, a surface low will intensify over MO/IL, shifting northeast along the OH River through the period. A very moist and unstable airmass is depicted ahead of the low and attendant south/southeastward-progressing cold front. Intense severe thunderstorms will likely accompany this system. Consistency among deterministic guidance, favorable synoptic pattern, as well as CSU/NSSL ML output, support introduction of 15 percent probabilities for Sunday. ...Days 7-8/Mon-Tue... Spread among forecast guidance increases substantially by the end of the forecast period. However, a pattern shift by Day 8/Tue appears possible, with an amplified upper ridge potentially building over the western half of the CONUS. Overall, predictability is too low to delineate areas of severe potential across the eastern half of the CONUS. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0404 AM CDT Tue May 21 2024 Valid 241200Z - 291200Z ...DISCUSSION... ...Day 4/Fri - Mid MS Valley/Upper Great Lakes vicinity... An upper shortwave trough over the northern Plains will pivot northeast across the Upper Midwest on Friday. At the surface, low pressure will develop northward across MN/WI and a trailing cold front will push east, becoming positioned from WI to central OK/MO by Saturday morning. Some severe potential is possible ahead of the front from the Mid-MS Valley into the Great Lakes vicinity. However, ongoing convection early Friday and large-scale ascent lifting northeast of the region with time is resulting in uncertainty. Severe probabilities will likely be needed in subsequent outlooks as mesoscale details become better resolved, but confidence is too low to delineate an unconditional 15 percent probability at this time. ...Day 5/Sat - Southern Plains to the Ozarks vicinity... Low-amplitude west/southwest mid/upper flow is forecast across the southern Plains to the Mid-South vicinity for much of the diurnal period on Saturday. By 00z, forecast guidance suggests a shortwave trough will eject from the southern Rockies into the southern Plains, and eventually impinging on the Ozarks/Mid-South area by Sunday morning. A very moist and unstable airmass is forecast over the southern Plains vicinity ahead of this feature as a surface warm front lifts northward through the day. Increasing ascent may not arrive until after 00-03z, limiting convective initiation until the nighttime hours. If storms can develop during the day across portions of OK/TX, all hazards severe potential will exist. Otherwise, thunderstorm potential may be more likely during the evening/overnight from north TX into southeast OK and AR as large-scale ascent increases and a 65-75 kt 500 mb jet overspreads the region. The north and west bounds of severe potential are a bit uncertain, so this area may shift in subsequent outlooks. ...Day 6/Sun - Ozarks to the Lower OH and TN Valleys... An upper shortwave trough will progress across the region on Sunday. Forecast guidance depicts a 50-60 kt southwesterly 700 mb jet overspreading the region during the day. Meanwhile, a surface low will intensify over MO/IL, shifting northeast along the OH River through the period. A very moist and unstable airmass is depicted ahead of the low and attendant south/southeastward-progressing cold front. Intense severe thunderstorms will likely accompany this system. Consistency among deterministic guidance, favorable synoptic pattern, as well as CSU/NSSL ML output, support introduction of 15 percent probabilities for Sunday. ...Days 7-8/Mon-Tue... Spread among forecast guidance increases substantially by the end of the forecast period. However, a pattern shift by Day 8/Tue appears possible, with an amplified upper ridge potentially building over the western half of the CONUS. Overall, predictability is too low to delineate areas of severe potential across the eastern half of the CONUS. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0404 AM CDT Tue May 21 2024 Valid 241200Z - 291200Z ...DISCUSSION... ...Day 4/Fri - Mid MS Valley/Upper Great Lakes vicinity... An upper shortwave trough over the northern Plains will pivot northeast across the Upper Midwest on Friday. At the surface, low pressure will develop northward across MN/WI and a trailing cold front will push east, becoming positioned from WI to central OK/MO by Saturday morning. Some severe potential is possible ahead of the front from the Mid-MS Valley into the Great Lakes vicinity. However, ongoing convection early Friday and large-scale ascent lifting northeast of the region with time is resulting in uncertainty. Severe probabilities will likely be needed in subsequent outlooks as mesoscale details become better resolved, but confidence is too low to delineate an unconditional 15 percent probability at this time. ...Day 5/Sat - Southern Plains to the Ozarks vicinity... Low-amplitude west/southwest mid/upper flow is forecast across the southern Plains to the Mid-South vicinity for much of the diurnal period on Saturday. By 00z, forecast guidance suggests a shortwave trough will eject from the southern Rockies into the southern Plains, and eventually impinging on the Ozarks/Mid-South area by Sunday morning. A very moist and unstable airmass is forecast over the southern Plains vicinity ahead of this feature as a surface warm front lifts northward through the day. Increasing ascent may not arrive until after 00-03z, limiting convective initiation until the nighttime hours. If storms can develop during the day across portions of OK/TX, all hazards severe potential will exist. Otherwise, thunderstorm potential may be more likely during the evening/overnight from north TX into southeast OK and AR as large-scale ascent increases and a 65-75 kt 500 mb jet overspreads the region. The north and west bounds of severe potential are a bit uncertain, so this area may shift in subsequent outlooks. ...Day 6/Sun - Ozarks to the Lower OH and TN Valleys... An upper shortwave trough will progress across the region on Sunday. Forecast guidance depicts a 50-60 kt southwesterly 700 mb jet overspreading the region during the day. Meanwhile, a surface low will intensify over MO/IL, shifting northeast along the OH River through the period. A very moist and unstable airmass is depicted ahead of the low and attendant south/southeastward-progressing cold front. Intense severe thunderstorms will likely accompany this system. Consistency among deterministic guidance, favorable synoptic pattern, as well as CSU/NSSL ML output, support introduction of 15 percent probabilities for Sunday. ...Days 7-8/Mon-Tue... Spread among forecast guidance increases substantially by the end of the forecast period. However, a pattern shift by Day 8/Tue appears possible, with an amplified upper ridge potentially building over the western half of the CONUS. Overall, predictability is too low to delineate areas of severe potential across the eastern half of the CONUS. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0404 AM CDT Tue May 21 2024 Valid 241200Z - 291200Z ...DISCUSSION... ...Day 4/Fri - Mid MS Valley/Upper Great Lakes vicinity... An upper shortwave trough over the northern Plains will pivot northeast across the Upper Midwest on Friday. At the surface, low pressure will develop northward across MN/WI and a trailing cold front will push east, becoming positioned from WI to central OK/MO by Saturday morning. Some severe potential is possible ahead of the front from the Mid-MS Valley into the Great Lakes vicinity. However, ongoing convection early Friday and large-scale ascent lifting northeast of the region with time is resulting in uncertainty. Severe probabilities will likely be needed in subsequent outlooks as mesoscale details become better resolved, but confidence is too low to delineate an unconditional 15 percent probability at this time. ...Day 5/Sat - Southern Plains to the Ozarks vicinity... Low-amplitude west/southwest mid/upper flow is forecast across the southern Plains to the Mid-South vicinity for much of the diurnal period on Saturday. By 00z, forecast guidance suggests a shortwave trough will eject from the southern Rockies into the southern Plains, and eventually impinging on the Ozarks/Mid-South area by Sunday morning. A very moist and unstable airmass is forecast over the southern Plains vicinity ahead of this feature as a surface warm front lifts northward through the day. Increasing ascent may not arrive until after 00-03z, limiting convective initiation until the nighttime hours. If storms can develop during the day across portions of OK/TX, all hazards severe potential will exist. Otherwise, thunderstorm potential may be more likely during the evening/overnight from north TX into southeast OK and AR as large-scale ascent increases and a 65-75 kt 500 mb jet overspreads the region. The north and west bounds of severe potential are a bit uncertain, so this area may shift in subsequent outlooks. ...Day 6/Sun - Ozarks to the Lower OH and TN Valleys... An upper shortwave trough will progress across the region on Sunday. Forecast guidance depicts a 50-60 kt southwesterly 700 mb jet overspreading the region during the day. Meanwhile, a surface low will intensify over MO/IL, shifting northeast along the OH River through the period. A very moist and unstable airmass is depicted ahead of the low and attendant south/southeastward-progressing cold front. Intense severe thunderstorms will likely accompany this system. Consistency among deterministic guidance, favorable synoptic pattern, as well as CSU/NSSL ML output, support introduction of 15 percent probabilities for Sunday. ...Days 7-8/Mon-Tue... Spread among forecast guidance increases substantially by the end of the forecast period. However, a pattern shift by Day 8/Tue appears possible, with an amplified upper ridge potentially building over the western half of the CONUS. Overall, predictability is too low to delineate areas of severe potential across the eastern half of the CONUS. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0404 AM CDT Tue May 21 2024 Valid 241200Z - 291200Z ...DISCUSSION... ...Day 4/Fri - Mid MS Valley/Upper Great Lakes vicinity... An upper shortwave trough over the northern Plains will pivot northeast across the Upper Midwest on Friday. At the surface, low pressure will develop northward across MN/WI and a trailing cold front will push east, becoming positioned from WI to central OK/MO by Saturday morning. Some severe potential is possible ahead of the front from the Mid-MS Valley into the Great Lakes vicinity. However, ongoing convection early Friday and large-scale ascent lifting northeast of the region with time is resulting in uncertainty. Severe probabilities will likely be needed in subsequent outlooks as mesoscale details become better resolved, but confidence is too low to delineate an unconditional 15 percent probability at this time. ...Day 5/Sat - Southern Plains to the Ozarks vicinity... Low-amplitude west/southwest mid/upper flow is forecast across the southern Plains to the Mid-South vicinity for much of the diurnal period on Saturday. By 00z, forecast guidance suggests a shortwave trough will eject from the southern Rockies into the southern Plains, and eventually impinging on the Ozarks/Mid-South area by Sunday morning. A very moist and unstable airmass is forecast over the southern Plains vicinity ahead of this feature as a surface warm front lifts northward through the day. Increasing ascent may not arrive until after 00-03z, limiting convective initiation until the nighttime hours. If storms can develop during the day across portions of OK/TX, all hazards severe potential will exist. Otherwise, thunderstorm potential may be more likely during the evening/overnight from north TX into southeast OK and AR as large-scale ascent increases and a 65-75 kt 500 mb jet overspreads the region. The north and west bounds of severe potential are a bit uncertain, so this area may shift in subsequent outlooks. ...Day 6/Sun - Ozarks to the Lower OH and TN Valleys... An upper shortwave trough will progress across the region on Sunday. Forecast guidance depicts a 50-60 kt southwesterly 700 mb jet overspreading the region during the day. Meanwhile, a surface low will intensify over MO/IL, shifting northeast along the OH River through the period. A very moist and unstable airmass is depicted ahead of the low and attendant south/southeastward-progressing cold front. Intense severe thunderstorms will likely accompany this system. Consistency among deterministic guidance, favorable synoptic pattern, as well as CSU/NSSL ML output, support introduction of 15 percent probabilities for Sunday. ...Days 7-8/Mon-Tue... Spread among forecast guidance increases substantially by the end of the forecast period. However, a pattern shift by Day 8/Tue appears possible, with an amplified upper ridge potentially building over the western half of the CONUS. Overall, predictability is too low to delineate areas of severe potential across the eastern half of the CONUS. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0404 AM CDT Tue May 21 2024 Valid 241200Z - 291200Z ...DISCUSSION... ...Day 4/Fri - Mid MS Valley/Upper Great Lakes vicinity... An upper shortwave trough over the northern Plains will pivot northeast across the Upper Midwest on Friday. At the surface, low pressure will develop northward across MN/WI and a trailing cold front will push east, becoming positioned from WI to central OK/MO by Saturday morning. Some severe potential is possible ahead of the front from the Mid-MS Valley into the Great Lakes vicinity. However, ongoing convection early Friday and large-scale ascent lifting northeast of the region with time is resulting in uncertainty. Severe probabilities will likely be needed in subsequent outlooks as mesoscale details become better resolved, but confidence is too low to delineate an unconditional 15 percent probability at this time. ...Day 5/Sat - Southern Plains to the Ozarks vicinity... Low-amplitude west/southwest mid/upper flow is forecast across the southern Plains to the Mid-South vicinity for much of the diurnal period on Saturday. By 00z, forecast guidance suggests a shortwave trough will eject from the southern Rockies into the southern Plains, and eventually impinging on the Ozarks/Mid-South area by Sunday morning. A very moist and unstable airmass is forecast over the southern Plains vicinity ahead of this feature as a surface warm front lifts northward through the day. Increasing ascent may not arrive until after 00-03z, limiting convective initiation until the nighttime hours. If storms can develop during the day across portions of OK/TX, all hazards severe potential will exist. Otherwise, thunderstorm potential may be more likely during the evening/overnight from north TX into southeast OK and AR as large-scale ascent increases and a 65-75 kt 500 mb jet overspreads the region. The north and west bounds of severe potential are a bit uncertain, so this area may shift in subsequent outlooks. ...Day 6/Sun - Ozarks to the Lower OH and TN Valleys... An upper shortwave trough will progress across the region on Sunday. Forecast guidance depicts a 50-60 kt southwesterly 700 mb jet overspreading the region during the day. Meanwhile, a surface low will intensify over MO/IL, shifting northeast along the OH River through the period. A very moist and unstable airmass is depicted ahead of the low and attendant south/southeastward-progressing cold front. Intense severe thunderstorms will likely accompany this system. Consistency among deterministic guidance, favorable synoptic pattern, as well as CSU/NSSL ML output, support introduction of 15 percent probabilities for Sunday. ...Days 7-8/Mon-Tue... Spread among forecast guidance increases substantially by the end of the forecast period. However, a pattern shift by Day 8/Tue appears possible, with an amplified upper ridge potentially building over the western half of the CONUS. Overall, predictability is too low to delineate areas of severe potential across the eastern half of the CONUS. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0404 AM CDT Tue May 21 2024 Valid 241200Z - 291200Z ...DISCUSSION... ...Day 4/Fri - Mid MS Valley/Upper Great Lakes vicinity... An upper shortwave trough over the northern Plains will pivot northeast across the Upper Midwest on Friday. At the surface, low pressure will develop northward across MN/WI and a trailing cold front will push east, becoming positioned from WI to central OK/MO by Saturday morning. Some severe potential is possible ahead of the front from the Mid-MS Valley into the Great Lakes vicinity. However, ongoing convection early Friday and large-scale ascent lifting northeast of the region with time is resulting in uncertainty. Severe probabilities will likely be needed in subsequent outlooks as mesoscale details become better resolved, but confidence is too low to delineate an unconditional 15 percent probability at this time. ...Day 5/Sat - Southern Plains to the Ozarks vicinity... Low-amplitude west/southwest mid/upper flow is forecast across the southern Plains to the Mid-South vicinity for much of the diurnal period on Saturday. By 00z, forecast guidance suggests a shortwave trough will eject from the southern Rockies into the southern Plains, and eventually impinging on the Ozarks/Mid-South area by Sunday morning. A very moist and unstable airmass is forecast over the southern Plains vicinity ahead of this feature as a surface warm front lifts northward through the day. Increasing ascent may not arrive until after 00-03z, limiting convective initiation until the nighttime hours. If storms can develop during the day across portions of OK/TX, all hazards severe potential will exist. Otherwise, thunderstorm potential may be more likely during the evening/overnight from north TX into southeast OK and AR as large-scale ascent increases and a 65-75 kt 500 mb jet overspreads the region. The north and west bounds of severe potential are a bit uncertain, so this area may shift in subsequent outlooks. ...Day 6/Sun - Ozarks to the Lower OH and TN Valleys... An upper shortwave trough will progress across the region on Sunday. Forecast guidance depicts a 50-60 kt southwesterly 700 mb jet overspreading the region during the day. Meanwhile, a surface low will intensify over MO/IL, shifting northeast along the OH River through the period. A very moist and unstable airmass is depicted ahead of the low and attendant south/southeastward-progressing cold front. Intense severe thunderstorms will likely accompany this system. Consistency among deterministic guidance, favorable synoptic pattern, as well as CSU/NSSL ML output, support introduction of 15 percent probabilities for Sunday. ...Days 7-8/Mon-Tue... Spread among forecast guidance increases substantially by the end of the forecast period. However, a pattern shift by Day 8/Tue appears possible, with an amplified upper ridge potentially building over the western half of the CONUS. Overall, predictability is too low to delineate areas of severe potential across the eastern half of the CONUS. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0404 AM CDT Tue May 21 2024 Valid 241200Z - 291200Z ...DISCUSSION... ...Day 4/Fri - Mid MS Valley/Upper Great Lakes vicinity... An upper shortwave trough over the northern Plains will pivot northeast across the Upper Midwest on Friday. At the surface, low pressure will develop northward across MN/WI and a trailing cold front will push east, becoming positioned from WI to central OK/MO by Saturday morning. Some severe potential is possible ahead of the front from the Mid-MS Valley into the Great Lakes vicinity. However, ongoing convection early Friday and large-scale ascent lifting northeast of the region with time is resulting in uncertainty. Severe probabilities will likely be needed in subsequent outlooks as mesoscale details become better resolved, but confidence is too low to delineate an unconditional 15 percent probability at this time. ...Day 5/Sat - Southern Plains to the Ozarks vicinity... Low-amplitude west/southwest mid/upper flow is forecast across the southern Plains to the Mid-South vicinity for much of the diurnal period on Saturday. By 00z, forecast guidance suggests a shortwave trough will eject from the southern Rockies into the southern Plains, and eventually impinging on the Ozarks/Mid-South area by Sunday morning. A very moist and unstable airmass is forecast over the southern Plains vicinity ahead of this feature as a surface warm front lifts northward through the day. Increasing ascent may not arrive until after 00-03z, limiting convective initiation until the nighttime hours. If storms can develop during the day across portions of OK/TX, all hazards severe potential will exist. Otherwise, thunderstorm potential may be more likely during the evening/overnight from north TX into southeast OK and AR as large-scale ascent increases and a 65-75 kt 500 mb jet overspreads the region. The north and west bounds of severe potential are a bit uncertain, so this area may shift in subsequent outlooks. ...Day 6/Sun - Ozarks to the Lower OH and TN Valleys... An upper shortwave trough will progress across the region on Sunday. Forecast guidance depicts a 50-60 kt southwesterly 700 mb jet overspreading the region during the day. Meanwhile, a surface low will intensify over MO/IL, shifting northeast along the OH River through the period. A very moist and unstable airmass is depicted ahead of the low and attendant south/southeastward-progressing cold front. Intense severe thunderstorms will likely accompany this system. Consistency among deterministic guidance, favorable synoptic pattern, as well as CSU/NSSL ML output, support introduction of 15 percent probabilities for Sunday. ...Days 7-8/Mon-Tue... Spread among forecast guidance increases substantially by the end of the forecast period. However, a pattern shift by Day 8/Tue appears possible, with an amplified upper ridge potentially building over the western half of the CONUS. Overall, predictability is too low to delineate areas of severe potential across the eastern half of the CONUS. Read more

WW 0274 Status Updates
STATUS REPORT ON WW 274 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 40 NE HLC TO 5 NE BUB. ..GOSS..05/21/24 ATTN...WFO...OAX...GID...LBF... STATUS REPORT FOR WS 274 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS IAC085-129-133-155-165-211040- IA . IOWA COUNTIES INCLUDED ARE HARRISON MILLS MONONA POTTAWATTAMIE SHELBY KSC183-211040- KS . KANSAS COUNTIES INCLUDED ARE SMITH NEC001-003-011-019-021-023-025-035-037-039-053-055-059-061-067- 071-077-079-081-093-095-097-099-109-119-121-125-129-131-139-141- 143-151-153-155-159-163-167-169-173-175-177-179-181-183-185- 211040- NE . NEBRASKA COUNTIES INCLUDED ARE Read more