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MD 1746 CONCERNING SEVERE POTENTIAL...WATCH LIKELY FOR PORTIONS OF CENTRAL AND EASTERN MT INTO WESTERN ND/SD AND NORTHEAST WY
Mesoscale Discussion 1746 NWS Storm Prediction Center Norman OK 0259 PM CDT Mon Jul 21 2025 Areas affected...portions of central and eastern MT into western ND/SD and northeast WY Concerning...Severe potential...Watch likely Valid 211959Z - 212200Z Probability of Watch Issuance...80 percent SUMMARY...Severe thunderstorm potential will increase over the next 1-3 hours. Potential for large hail 2.5-3.0 inches in diameter, damaging gusts to 80 mph, and possibly a tornado will be possible into the evening hours. A severe thunderstorm watch is likely for parts of the discussion area by 22z. DISCUSSION...Isolated thunderstorms and increasing cumulus are noted near the higher terrain of northern WY/southern MT. This activity is developing within drier air and strong differential heating over higher terrain and as increasing large-scale ascent begins to impinge on the area from the west. With time, additional convection is expected to spread northeast into an axis of great boundary-layer moisture in the upper 50s to low 60s F from central MT into the western Dakotas. Favorable vertical shear amid a roughly west to east oriented tongue of modest to strong instability will support initial cells capable of large hail. Steepened low-level lapse rates and at least some modest dry air noted in forecast soundings centered around 700 mb suggests strong winds also will be possible. This may especially occur if any clusters/bows develop as a low-level jet increases during the evening, and with eastward into the western Dakotas. As storms interact with the moist axis across southeast MT, some potential will exist for a tornado or two if capping is sufficiently eroded and where backed low-level winds will result in locally enhanced 0-1 km SRH. Initial severe thunderstorm watch issuance is expected by 22z, though eastern extent of watch issuance is a bit uncertain and may or may not extend into the western Dakotas with this watch issuance. ..Leitman/Smith.. 07/21/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BIS...UNR...BYZ...GGW...TFX... LAT...LON 44260422 44220359 44340317 44820295 45760286 46920302 47720348 48090542 47840790 47101010 46681056 46231074 45551031 45170739 44880570 44260422 MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 95 MPH MOST PROBABLE PEAK WIND GUST...65-80 MPH MOST PROBABLE PEAK HAIL SIZE...2.00-3.50 IN Read more

WW 0535 Status Updates
STATUS FOR WATCH 0535 HAS NOT BEEN ISSUED YET Read more

WW 0535 Status Updates
STATUS FOR WATCH 0535 HAS NOT BEEN ISSUED YET Read more

WW 0535 Status Updates
STATUS FOR WATCH 0535 HAS NOT BEEN ISSUED YET Read more

WW 535 SEVERE TSTM MT ND SD WY 212135Z - 220500Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 535 NWS Storm Prediction Center Norman OK 335 PM MDT Mon Jul 21 2025 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Southeast Montana Southwest North Dakota Northwest South Dakota Northeast Wyoming * Effective this Monday afternoon and evening from 335 PM until 1100 PM MDT. * Primary threats include... Scattered large hail and isolated very large hail events to 2.5 inches in diameter possible Scattered damaging wind gusts to 70 mph possible A tornado or two possible SUMMARY...Thunderstorms will continue to develop and intensify across parts of northeast Wyoming and southeast Montana through the late afternoon. These storms will track northeastward across the watch area, posing a risk of large hail and damaging wind gusts. The severe thunderstorm watch area is approximately along and 75 statute miles north and south of a line from 60 miles northwest of Billings MT to 25 miles east northeast of Buffalo SD. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU5). 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. && AVIATION...A few severe thunderstorms with hail surface and aloft to 2.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 25030. ...Hart Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1227 PM CDT Mon Jul 21 2025 Valid 221200Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY... ...SUMMARY... Scattered severe thunderstorms are expected over parts of the northern Plains into the upper Mississippi Valley Tuesday and Tuesday night. Isolated strong wind gusts may occur over parts of the Southeast during the afternoon. ...Northern Plains to Upper MS Valley... Southwest flow aloft will persist over the region on Tuesday, with an early wave associated with ongoing convection expected from ND into northern MN. This activity will be supported by a southerly low-level jet around 40 kt. Some of this activity may be elevated early on with a warm front into northern MN, however, the ample instability and PWAT may still lead to damaging winds. In addition, large hail will be possible, conditional on storm mode, given strong deep-layer shear. South of this activity, very strong instability is forecast, with MLCAPE to around 4000 J/kg. This will develop ahead of a cold front from near the Red River southwestward into central SD, and south of the effective warm front over northern MN. Storms are expected to develop along the front near 00Z, and persist into the evening across much of MN and into western WI and perhaps western Upper MI. Eventual upscale growth to an MCS with damaging winds is most likely. While predictability is low for exact placement of MCSs, greater concentrations may occur anywhere within the Slight Risk area. ...Southeast... Gradual height rises will occur over the area, with a surface trough developing with daytime heating from southeast GA into SC. The air mass will remain very moist with high PWAT content, and scattered afternoon storms will be common. Multiple initiation zones are likely, including elevated terrain, sea breeze, and surface trough. Areas of strong outflow are likely, with some damaging gusts possible. ..Jewell.. 07/21/2025 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1227 PM CDT Mon Jul 21 2025 Valid 221200Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY... ...SUMMARY... Scattered severe thunderstorms are expected over parts of the northern Plains into the upper Mississippi Valley Tuesday and Tuesday night. Isolated strong wind gusts may occur over parts of the Southeast during the afternoon. ...Northern Plains to Upper MS Valley... Southwest flow aloft will persist over the region on Tuesday, with an early wave associated with ongoing convection expected from ND into northern MN. This activity will be supported by a southerly low-level jet around 40 kt. Some of this activity may be elevated early on with a warm front into northern MN, however, the ample instability and PWAT may still lead to damaging winds. In addition, large hail will be possible, conditional on storm mode, given strong deep-layer shear. South of this activity, very strong instability is forecast, with MLCAPE to around 4000 J/kg. This will develop ahead of a cold front from near the Red River southwestward into central SD, and south of the effective warm front over northern MN. Storms are expected to develop along the front near 00Z, and persist into the evening across much of MN and into western WI and perhaps western Upper MI. Eventual upscale growth to an MCS with damaging winds is most likely. While predictability is low for exact placement of MCSs, greater concentrations may occur anywhere within the Slight Risk area. ...Southeast... Gradual height rises will occur over the area, with a surface trough developing with daytime heating from southeast GA into SC. The air mass will remain very moist with high PWAT content, and scattered afternoon storms will be common. Multiple initiation zones are likely, including elevated terrain, sea breeze, and surface trough. Areas of strong outflow are likely, with some damaging gusts possible. ..Jewell.. 07/21/2025 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1227 PM CDT Mon Jul 21 2025 Valid 221200Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY... ...SUMMARY... Scattered severe thunderstorms are expected over parts of the northern Plains into the upper Mississippi Valley Tuesday and Tuesday night. Isolated strong wind gusts may occur over parts of the Southeast during the afternoon. ...Northern Plains to Upper MS Valley... Southwest flow aloft will persist over the region on Tuesday, with an early wave associated with ongoing convection expected from ND into northern MN. This activity will be supported by a southerly low-level jet around 40 kt. Some of this activity may be elevated early on with a warm front into northern MN, however, the ample instability and PWAT may still lead to damaging winds. In addition, large hail will be possible, conditional on storm mode, given strong deep-layer shear. South of this activity, very strong instability is forecast, with MLCAPE to around 4000 J/kg. This will develop ahead of a cold front from near the Red River southwestward into central SD, and south of the effective warm front over northern MN. Storms are expected to develop along the front near 00Z, and persist into the evening across much of MN and into western WI and perhaps western Upper MI. Eventual upscale growth to an MCS with damaging winds is most likely. While predictability is low for exact placement of MCSs, greater concentrations may occur anywhere within the Slight Risk area. ...Southeast... Gradual height rises will occur over the area, with a surface trough developing with daytime heating from southeast GA into SC. The air mass will remain very moist with high PWAT content, and scattered afternoon storms will be common. Multiple initiation zones are likely, including elevated terrain, sea breeze, and surface trough. Areas of strong outflow are likely, with some damaging gusts possible. ..Jewell.. 07/21/2025 Read more

No watches are valid as of Mon Jul 21 21:07:02 UTC 2025.

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0255 PM CDT Mon Jul 21 2025 Valid 212000Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN PLAINS... ...SUMMARY... Severe thunderstorms capable of producing large hail, severe gusts, and perhaps a tornado or two will be possible late this afternoon into tonight across parts of the northern Plains. ...20Z Update... The previous forecast remains on track, and only minor adjustments were made with this update. In the northern Plains, the Slight risk was expanded eastward in portions of ND, driven by 15-percent wind probabilities. The latest model guidance is in relatively good agreement, depicting an eastward-moving cluster of storms through the early morning hours -- aided by a strengthening low-level jet and convectively augmented midlevel impulse. Farther south, the Marginal risk was expanded slightly southward across central KS. Here, continued diurnal heating/destabilization amid rich boundary-layer moisture and steep lapse rates will favor severe wind gusts with any storm clusters that evolve through this evening. ..Weinman.. 07/21/2025 .PREV DISCUSSION... /ISSUED 1132 AM CDT Mon Jul 21 2025/ ...Northern Plains into the Upper Midwest... Water-vapor imagery shows a mid-level trough progressing eastward across the Pacific Northwest towards the northern Rockies. A lead mid-level vorticity max rotating through the base of the trough is forecast to pivot east-northeastward from north-central ID into MT by the early evening. In the low levels, a stationary frontal zone extends from near the NE/SD border west-northwestward to near the ID/WY/MT border with an easterly component to the low-level flow being maintained across eastern into central portions of MT. A moisture plume protrudes northwestward along and north of this boundary with a reservoir of 70s F dewpoints over NE to lower 60s in southeast MT (850-mb dewpoints around 16 deg C per objective analysis). A notable capping inversion will likely inhibit storm development until mid afternoon and the initial storm activity will likely focus near higher terrain and over southern MT. Steep mid-level lapse rates and 30-45 kt southwesterly 500-mb flow will support supercells with large to very large hail accompanying these storms from near the Black Hills into southern MT. A tornado risk may develop where locally backed flow in the presence of smaller temperature-dewpoint spreads could evolve near the boundary. Upscale growth into one or more clusters or an MCS seems plausible this evening into the overnight as storms move/develop east into the Dakotas. ...Central Plains... No change was made to the previous forecast for the Central Plains region. Much of the central Plains will remain capped today, as the upper ridge and warm temperatures aloft exert their influence. A surface trough is expected to extend southward across the central High Plains this afternoon, and a remnant MCV related to earlier convection should move eastward along/near the NE/KS border. Both of these features may aid in at least isolated thunderstorm development this afternoon, in the presence of moderate to strong instability amid modest deep-layer shear. Isolated severe hail and wind gusts may occur with any of the more robust cores that can develop and be maintained in an otherwise weak forcing regime. ...Tennessee Valley into the Southeast... Midday visible-satellite imagery shows an agitated cumulus field from southern GA northwestward into the southern Appalachians and Cumberland Plateau. 12 UTC raobs from Jacksonville, Atlanta, and Charleston showed PW in excess of 2 inches, signifying a very moist, deep troposphere. Surface temperatures will continue to warm into the 90s F, thereby steepening 0-2 km lapse rates. As storms develop, some of the stronger water-loaded downdrafts may yield a threat for localized 50-65 mph gusts and pockets of wind damage. This activity will likely diminish by the evening. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0255 PM CDT Mon Jul 21 2025 Valid 212000Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN PLAINS... ...SUMMARY... Severe thunderstorms capable of producing large hail, severe gusts, and perhaps a tornado or two will be possible late this afternoon into tonight across parts of the northern Plains. ...20Z Update... The previous forecast remains on track, and only minor adjustments were made with this update. In the northern Plains, the Slight risk was expanded eastward in portions of ND, driven by 15-percent wind probabilities. The latest model guidance is in relatively good agreement, depicting an eastward-moving cluster of storms through the early morning hours -- aided by a strengthening low-level jet and convectively augmented midlevel impulse. Farther south, the Marginal risk was expanded slightly southward across central KS. Here, continued diurnal heating/destabilization amid rich boundary-layer moisture and steep lapse rates will favor severe wind gusts with any storm clusters that evolve through this evening. ..Weinman.. 07/21/2025 .PREV DISCUSSION... /ISSUED 1132 AM CDT Mon Jul 21 2025/ ...Northern Plains into the Upper Midwest... Water-vapor imagery shows a mid-level trough progressing eastward across the Pacific Northwest towards the northern Rockies. A lead mid-level vorticity max rotating through the base of the trough is forecast to pivot east-northeastward from north-central ID into MT by the early evening. In the low levels, a stationary frontal zone extends from near the NE/SD border west-northwestward to near the ID/WY/MT border with an easterly component to the low-level flow being maintained across eastern into central portions of MT. A moisture plume protrudes northwestward along and north of this boundary with a reservoir of 70s F dewpoints over NE to lower 60s in southeast MT (850-mb dewpoints around 16 deg C per objective analysis). A notable capping inversion will likely inhibit storm development until mid afternoon and the initial storm activity will likely focus near higher terrain and over southern MT. Steep mid-level lapse rates and 30-45 kt southwesterly 500-mb flow will support supercells with large to very large hail accompanying these storms from near the Black Hills into southern MT. A tornado risk may develop where locally backed flow in the presence of smaller temperature-dewpoint spreads could evolve near the boundary. Upscale growth into one or more clusters or an MCS seems plausible this evening into the overnight as storms move/develop east into the Dakotas. ...Central Plains... No change was made to the previous forecast for the Central Plains region. Much of the central Plains will remain capped today, as the upper ridge and warm temperatures aloft exert their influence. A surface trough is expected to extend southward across the central High Plains this afternoon, and a remnant MCV related to earlier convection should move eastward along/near the NE/KS border. Both of these features may aid in at least isolated thunderstorm development this afternoon, in the presence of moderate to strong instability amid modest deep-layer shear. Isolated severe hail and wind gusts may occur with any of the more robust cores that can develop and be maintained in an otherwise weak forcing regime. ...Tennessee Valley into the Southeast... Midday visible-satellite imagery shows an agitated cumulus field from southern GA northwestward into the southern Appalachians and Cumberland Plateau. 12 UTC raobs from Jacksonville, Atlanta, and Charleston showed PW in excess of 2 inches, signifying a very moist, deep troposphere. Surface temperatures will continue to warm into the 90s F, thereby steepening 0-2 km lapse rates. As storms develop, some of the stronger water-loaded downdrafts may yield a threat for localized 50-65 mph gusts and pockets of wind damage. This activity will likely diminish by the evening. Read more

No Mesoscale Discussions are in effect as of Mon Jul 21 20:00:02 UTC 2025.

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0226 PM CDT Mon Jul 21 2025 Valid 231200Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE UPPER MISSISSIPPI VALLEY TO UPPER GREAT LAKES REGION... ...SUMMARY... A few organizing clusters of storms posing a risk for severe wind and perhaps some hail are possible across parts of the Upper Midwest into adjacent Great Lakes region Wednesday through Wednesday night. ...Discussion... An upper ridge will exist over the eastern CONUS, with a belt of moderate winds aloft from the upper MS Valley and Great Lakes. A surface trough will extend roughly from Lake Superior southwestward into NE, with rich moisture to the south and east. Storms are likely to be ongoing over the upper Great Lakes region early on Wednesday, supported by southwest winds at 850 mb within a theta-e plume. Some of this early activity could product strong wind gusts. Behind this activity, destabilization will occur near the surface trough, and new development is likely during the late afternoon from MN into SD and NE. With only subtle features aloft, this activity will likely develop into clusters of storms with east/southeastward propagation and attendant outflow/severe gust threat. Otherwise, isolated severe cells with hail will be possible over the High Plains over southeast MT, eastern WY and CO, as moisture backs westward into the steeper lapse rate environment. Longer hodographs over MT/WY could support a supercell or two, and this area will be monitored for higher probabilities in later outlooks. ..Jewell.. 07/21/2025 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0226 PM CDT Mon Jul 21 2025 Valid 231200Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE UPPER MISSISSIPPI VALLEY TO UPPER GREAT LAKES REGION... ...SUMMARY... A few organizing clusters of storms posing a risk for severe wind and perhaps some hail are possible across parts of the Upper Midwest into adjacent Great Lakes region Wednesday through Wednesday night. ...Discussion... An upper ridge will exist over the eastern CONUS, with a belt of moderate winds aloft from the upper MS Valley and Great Lakes. A surface trough will extend roughly from Lake Superior southwestward into NE, with rich moisture to the south and east. Storms are likely to be ongoing over the upper Great Lakes region early on Wednesday, supported by southwest winds at 850 mb within a theta-e plume. Some of this early activity could product strong wind gusts. Behind this activity, destabilization will occur near the surface trough, and new development is likely during the late afternoon from MN into SD and NE. With only subtle features aloft, this activity will likely develop into clusters of storms with east/southeastward propagation and attendant outflow/severe gust threat. Otherwise, isolated severe cells with hail will be possible over the High Plains over southeast MT, eastern WY and CO, as moisture backs westward into the steeper lapse rate environment. Longer hodographs over MT/WY could support a supercell or two, and this area will be monitored for higher probabilities in later outlooks. ..Jewell.. 07/21/2025 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0226 PM CDT Mon Jul 21 2025 Valid 231200Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE UPPER MISSISSIPPI VALLEY TO UPPER GREAT LAKES REGION... ...SUMMARY... A few organizing clusters of storms posing a risk for severe wind and perhaps some hail are possible across parts of the Upper Midwest into adjacent Great Lakes region Wednesday through Wednesday night. ...Discussion... An upper ridge will exist over the eastern CONUS, with a belt of moderate winds aloft from the upper MS Valley and Great Lakes. A surface trough will extend roughly from Lake Superior southwestward into NE, with rich moisture to the south and east. Storms are likely to be ongoing over the upper Great Lakes region early on Wednesday, supported by southwest winds at 850 mb within a theta-e plume. Some of this early activity could product strong wind gusts. Behind this activity, destabilization will occur near the surface trough, and new development is likely during the late afternoon from MN into SD and NE. With only subtle features aloft, this activity will likely develop into clusters of storms with east/southeastward propagation and attendant outflow/severe gust threat. Otherwise, isolated severe cells with hail will be possible over the High Plains over southeast MT, eastern WY and CO, as moisture backs westward into the steeper lapse rate environment. Longer hodographs over MT/WY could support a supercell or two, and this area will be monitored for higher probabilities in later outlooks. ..Jewell.. 07/21/2025 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0226 PM CDT Mon Jul 21 2025 Valid 231200Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE UPPER MISSISSIPPI VALLEY TO UPPER GREAT LAKES REGION... ...SUMMARY... A few organizing clusters of storms posing a risk for severe wind and perhaps some hail are possible across parts of the Upper Midwest into adjacent Great Lakes region Wednesday through Wednesday night. ...Discussion... An upper ridge will exist over the eastern CONUS, with a belt of moderate winds aloft from the upper MS Valley and Great Lakes. A surface trough will extend roughly from Lake Superior southwestward into NE, with rich moisture to the south and east. Storms are likely to be ongoing over the upper Great Lakes region early on Wednesday, supported by southwest winds at 850 mb within a theta-e plume. Some of this early activity could product strong wind gusts. Behind this activity, destabilization will occur near the surface trough, and new development is likely during the late afternoon from MN into SD and NE. With only subtle features aloft, this activity will likely develop into clusters of storms with east/southeastward propagation and attendant outflow/severe gust threat. Otherwise, isolated severe cells with hail will be possible over the High Plains over southeast MT, eastern WY and CO, as moisture backs westward into the steeper lapse rate environment. Longer hodographs over MT/WY could support a supercell or two, and this area will be monitored for higher probabilities in later outlooks. ..Jewell.. 07/21/2025 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0226 PM CDT Mon Jul 21 2025 Valid 231200Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE UPPER MISSISSIPPI VALLEY TO UPPER GREAT LAKES REGION... ...SUMMARY... A few organizing clusters of storms posing a risk for severe wind and perhaps some hail are possible across parts of the Upper Midwest into adjacent Great Lakes region Wednesday through Wednesday night. ...Discussion... An upper ridge will exist over the eastern CONUS, with a belt of moderate winds aloft from the upper MS Valley and Great Lakes. A surface trough will extend roughly from Lake Superior southwestward into NE, with rich moisture to the south and east. Storms are likely to be ongoing over the upper Great Lakes region early on Wednesday, supported by southwest winds at 850 mb within a theta-e plume. Some of this early activity could product strong wind gusts. Behind this activity, destabilization will occur near the surface trough, and new development is likely during the late afternoon from MN into SD and NE. With only subtle features aloft, this activity will likely develop into clusters of storms with east/southeastward propagation and attendant outflow/severe gust threat. Otherwise, isolated severe cells with hail will be possible over the High Plains over southeast MT, eastern WY and CO, as moisture backs westward into the steeper lapse rate environment. Longer hodographs over MT/WY could support a supercell or two, and this area will be monitored for higher probabilities in later outlooks. ..Jewell.. 07/21/2025 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0226 PM CDT Mon Jul 21 2025 Valid 231200Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE UPPER MISSISSIPPI VALLEY TO UPPER GREAT LAKES REGION... ...SUMMARY... A few organizing clusters of storms posing a risk for severe wind and perhaps some hail are possible across parts of the Upper Midwest into adjacent Great Lakes region Wednesday through Wednesday night. ...Discussion... An upper ridge will exist over the eastern CONUS, with a belt of moderate winds aloft from the upper MS Valley and Great Lakes. A surface trough will extend roughly from Lake Superior southwestward into NE, with rich moisture to the south and east. Storms are likely to be ongoing over the upper Great Lakes region early on Wednesday, supported by southwest winds at 850 mb within a theta-e plume. Some of this early activity could product strong wind gusts. Behind this activity, destabilization will occur near the surface trough, and new development is likely during the late afternoon from MN into SD and NE. With only subtle features aloft, this activity will likely develop into clusters of storms with east/southeastward propagation and attendant outflow/severe gust threat. Otherwise, isolated severe cells with hail will be possible over the High Plains over southeast MT, eastern WY and CO, as moisture backs westward into the steeper lapse rate environment. Longer hodographs over MT/WY could support a supercell or two, and this area will be monitored for higher probabilities in later outlooks. ..Jewell.. 07/21/2025 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0226 PM CDT Mon Jul 21 2025 Valid 231200Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE UPPER MISSISSIPPI VALLEY TO UPPER GREAT LAKES REGION... ...SUMMARY... A few organizing clusters of storms posing a risk for severe wind and perhaps some hail are possible across parts of the Upper Midwest into adjacent Great Lakes region Wednesday through Wednesday night. ...Discussion... An upper ridge will exist over the eastern CONUS, with a belt of moderate winds aloft from the upper MS Valley and Great Lakes. A surface trough will extend roughly from Lake Superior southwestward into NE, with rich moisture to the south and east. Storms are likely to be ongoing over the upper Great Lakes region early on Wednesday, supported by southwest winds at 850 mb within a theta-e plume. Some of this early activity could product strong wind gusts. Behind this activity, destabilization will occur near the surface trough, and new development is likely during the late afternoon from MN into SD and NE. With only subtle features aloft, this activity will likely develop into clusters of storms with east/southeastward propagation and attendant outflow/severe gust threat. Otherwise, isolated severe cells with hail will be possible over the High Plains over southeast MT, eastern WY and CO, as moisture backs westward into the steeper lapse rate environment. Longer hodographs over MT/WY could support a supercell or two, and this area will be monitored for higher probabilities in later outlooks. ..Jewell.. 07/21/2025 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0217 PM CDT Mon Jul 21 2025 Valid 221200Z - 231200Z No changes are needed to the D2 Fire Weather Outlook. ..Thornton.. 07/21/2025 .PREV DISCUSSION... /ISSUED 0201 AM CDT Mon Jul 21 2025/ ...Synopsis... The upper-level trough in the Northwest will become more diffuse on Tuesday. Mid-level winds will slacken across the Great Basin. A weak surface trough/boundary will remain in northern Nevada. ...Southern/central Nevada... While surface winds will generally be weaker than previous days, the surface pressure gradient near the boundary will support 15-20 mph in portions of southern/central Nevada. RH of 15-20% appears possible during the afternoon. Area fuels remain dry enough to support elevated fire weather conditions. ...Please see www.spc.noaa.gov/fire for graphic product... Read more