Severe Storms

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Mon Aug 18 2025 Valid 182000Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF NORTHERN ILLINOIS AND PARTS OF THE CENTRAL AND NORTHERN PLAINS... ...SUMMARY... Strong to severe storms capable of damaging winds are possible in parts of the Midwest today. Widely scattered storms with large hail and severe winds are possible in parts of the central/northern Plains through tonight. ...20Z Update... The primary change to the current Day 1 Outlook was to trim severe probabilities across portions of southern Wisconsin, where the passage of an MCS has resulted in low-level stabilization. Otherwise, only minor changes was made to severe/thunder probabilities to reflect the latest guidance and observations. ..Squitieri.. 08/18/2025 .PREV DISCUSSION... /ISSUED 1129 AM CDT Mon Aug 18 2025/ ...Mid MS Valley... Extensive outflow from last night's MCS currently extends from extreme southwest WI southwestward through eastern IA and north-central MO into eastern KS. This outflow has been moving quickly eastward/southeastward this morning, and this trend is expected to continue, although some slowing of its progression speed is possible over time. The downstream airmass across from southern WI and IL is characterized by dewpoints in the low to mid 70s. Mid-level lapse rates are generally poor across the region, but heating of this very moist airmass will still result in strong to very strong buoyancy (i.e. MLCAPE around 3000 J/kg) by late afternoon. Strong to severe storms are possible along this outflow as it impinges on this moist and buoyant airmass. Current trends suggest the greatest severe potential will exist this afternoon across southern WI and northern IL, where slightly stronger mid-level flow, backed surface winds, and an east-west baroclinic zone exists. Recently issued MCD 1983 addresses the short-term severe potential for this area. ...Central High Plains into the northern/central Plains... Strong heating and ample low/mid level moisture will promote the development of scattered thunderstorms by mid-afternoon over the foothills and plains of central/eastern CO. Additional isolated storms are possible farther north across western NE into the Black Hills region. Much of this area is within a corridor of modest mid-level flow on the northern periphery of the upper ridging covering the southern CONUS. Resulting modest shear may be enough for hail production with the initial development before these high-based storms trend towards outflow-dominant structures with time. These storms may persist into the evening, with an attendant threat for strong to severe gusts progressing into central NE before weakening. ...MO/AR... Clear skies and strong diurnal heating are expected across central/southern MO and much of AR. Temperatures in the upper 90s are expected, with dewpoints remaining in the mid 60s despite strong mixing. These hot and humid conditions will result in strong buoyancy this afternoon, with most guidance suggesting MLCAPE around 2000 J/kg. Shear will be weak, yielding mostly disorganized multicells, but the strongest storms will be capable of locally damaging wind gusts. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Mon Aug 18 2025 Valid 182000Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF NORTHERN ILLINOIS AND PARTS OF THE CENTRAL AND NORTHERN PLAINS... ...SUMMARY... Strong to severe storms capable of damaging winds are possible in parts of the Midwest today. Widely scattered storms with large hail and severe winds are possible in parts of the central/northern Plains through tonight. ...20Z Update... The primary change to the current Day 1 Outlook was to trim severe probabilities across portions of southern Wisconsin, where the passage of an MCS has resulted in low-level stabilization. Otherwise, only minor changes was made to severe/thunder probabilities to reflect the latest guidance and observations. ..Squitieri.. 08/18/2025 .PREV DISCUSSION... /ISSUED 1129 AM CDT Mon Aug 18 2025/ ...Mid MS Valley... Extensive outflow from last night's MCS currently extends from extreme southwest WI southwestward through eastern IA and north-central MO into eastern KS. This outflow has been moving quickly eastward/southeastward this morning, and this trend is expected to continue, although some slowing of its progression speed is possible over time. The downstream airmass across from southern WI and IL is characterized by dewpoints in the low to mid 70s. Mid-level lapse rates are generally poor across the region, but heating of this very moist airmass will still result in strong to very strong buoyancy (i.e. MLCAPE around 3000 J/kg) by late afternoon. Strong to severe storms are possible along this outflow as it impinges on this moist and buoyant airmass. Current trends suggest the greatest severe potential will exist this afternoon across southern WI and northern IL, where slightly stronger mid-level flow, backed surface winds, and an east-west baroclinic zone exists. Recently issued MCD 1983 addresses the short-term severe potential for this area. ...Central High Plains into the northern/central Plains... Strong heating and ample low/mid level moisture will promote the development of scattered thunderstorms by mid-afternoon over the foothills and plains of central/eastern CO. Additional isolated storms are possible farther north across western NE into the Black Hills region. Much of this area is within a corridor of modest mid-level flow on the northern periphery of the upper ridging covering the southern CONUS. Resulting modest shear may be enough for hail production with the initial development before these high-based storms trend towards outflow-dominant structures with time. These storms may persist into the evening, with an attendant threat for strong to severe gusts progressing into central NE before weakening. ...MO/AR... Clear skies and strong diurnal heating are expected across central/southern MO and much of AR. Temperatures in the upper 90s are expected, with dewpoints remaining in the mid 60s despite strong mixing. These hot and humid conditions will result in strong buoyancy this afternoon, with most guidance suggesting MLCAPE around 2000 J/kg. Shear will be weak, yielding mostly disorganized multicells, but the strongest storms will be capable of locally damaging wind gusts. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Mon Aug 18 2025 Valid 182000Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF NORTHERN ILLINOIS AND PARTS OF THE CENTRAL AND NORTHERN PLAINS... ...SUMMARY... Strong to severe storms capable of damaging winds are possible in parts of the Midwest today. Widely scattered storms with large hail and severe winds are possible in parts of the central/northern Plains through tonight. ...20Z Update... The primary change to the current Day 1 Outlook was to trim severe probabilities across portions of southern Wisconsin, where the passage of an MCS has resulted in low-level stabilization. Otherwise, only minor changes was made to severe/thunder probabilities to reflect the latest guidance and observations. ..Squitieri.. 08/18/2025 .PREV DISCUSSION... /ISSUED 1129 AM CDT Mon Aug 18 2025/ ...Mid MS Valley... Extensive outflow from last night's MCS currently extends from extreme southwest WI southwestward through eastern IA and north-central MO into eastern KS. This outflow has been moving quickly eastward/southeastward this morning, and this trend is expected to continue, although some slowing of its progression speed is possible over time. The downstream airmass across from southern WI and IL is characterized by dewpoints in the low to mid 70s. Mid-level lapse rates are generally poor across the region, but heating of this very moist airmass will still result in strong to very strong buoyancy (i.e. MLCAPE around 3000 J/kg) by late afternoon. Strong to severe storms are possible along this outflow as it impinges on this moist and buoyant airmass. Current trends suggest the greatest severe potential will exist this afternoon across southern WI and northern IL, where slightly stronger mid-level flow, backed surface winds, and an east-west baroclinic zone exists. Recently issued MCD 1983 addresses the short-term severe potential for this area. ...Central High Plains into the northern/central Plains... Strong heating and ample low/mid level moisture will promote the development of scattered thunderstorms by mid-afternoon over the foothills and plains of central/eastern CO. Additional isolated storms are possible farther north across western NE into the Black Hills region. Much of this area is within a corridor of modest mid-level flow on the northern periphery of the upper ridging covering the southern CONUS. Resulting modest shear may be enough for hail production with the initial development before these high-based storms trend towards outflow-dominant structures with time. These storms may persist into the evening, with an attendant threat for strong to severe gusts progressing into central NE before weakening. ...MO/AR... Clear skies and strong diurnal heating are expected across central/southern MO and much of AR. Temperatures in the upper 90s are expected, with dewpoints remaining in the mid 60s despite strong mixing. These hot and humid conditions will result in strong buoyancy this afternoon, with most guidance suggesting MLCAPE around 2000 J/kg. Shear will be weak, yielding mostly disorganized multicells, but the strongest storms will be capable of locally damaging wind gusts. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Mon Aug 18 2025 Valid 182000Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF NORTHERN ILLINOIS AND PARTS OF THE CENTRAL AND NORTHERN PLAINS... ...SUMMARY... Strong to severe storms capable of damaging winds are possible in parts of the Midwest today. Widely scattered storms with large hail and severe winds are possible in parts of the central/northern Plains through tonight. ...20Z Update... The primary change to the current Day 1 Outlook was to trim severe probabilities across portions of southern Wisconsin, where the passage of an MCS has resulted in low-level stabilization. Otherwise, only minor changes was made to severe/thunder probabilities to reflect the latest guidance and observations. ..Squitieri.. 08/18/2025 .PREV DISCUSSION... /ISSUED 1129 AM CDT Mon Aug 18 2025/ ...Mid MS Valley... Extensive outflow from last night's MCS currently extends from extreme southwest WI southwestward through eastern IA and north-central MO into eastern KS. This outflow has been moving quickly eastward/southeastward this morning, and this trend is expected to continue, although some slowing of its progression speed is possible over time. The downstream airmass across from southern WI and IL is characterized by dewpoints in the low to mid 70s. Mid-level lapse rates are generally poor across the region, but heating of this very moist airmass will still result in strong to very strong buoyancy (i.e. MLCAPE around 3000 J/kg) by late afternoon. Strong to severe storms are possible along this outflow as it impinges on this moist and buoyant airmass. Current trends suggest the greatest severe potential will exist this afternoon across southern WI and northern IL, where slightly stronger mid-level flow, backed surface winds, and an east-west baroclinic zone exists. Recently issued MCD 1983 addresses the short-term severe potential for this area. ...Central High Plains into the northern/central Plains... Strong heating and ample low/mid level moisture will promote the development of scattered thunderstorms by mid-afternoon over the foothills and plains of central/eastern CO. Additional isolated storms are possible farther north across western NE into the Black Hills region. Much of this area is within a corridor of modest mid-level flow on the northern periphery of the upper ridging covering the southern CONUS. Resulting modest shear may be enough for hail production with the initial development before these high-based storms trend towards outflow-dominant structures with time. These storms may persist into the evening, with an attendant threat for strong to severe gusts progressing into central NE before weakening. ...MO/AR... Clear skies and strong diurnal heating are expected across central/southern MO and much of AR. Temperatures in the upper 90s are expected, with dewpoints remaining in the mid 60s despite strong mixing. These hot and humid conditions will result in strong buoyancy this afternoon, with most guidance suggesting MLCAPE around 2000 J/kg. Shear will be weak, yielding mostly disorganized multicells, but the strongest storms will be capable of locally damaging wind gusts. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Mon Aug 18 2025 Valid 182000Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF NORTHERN ILLINOIS AND PARTS OF THE CENTRAL AND NORTHERN PLAINS... ...SUMMARY... Strong to severe storms capable of damaging winds are possible in parts of the Midwest today. Widely scattered storms with large hail and severe winds are possible in parts of the central/northern Plains through tonight. ...20Z Update... The primary change to the current Day 1 Outlook was to trim severe probabilities across portions of southern Wisconsin, where the passage of an MCS has resulted in low-level stabilization. Otherwise, only minor changes was made to severe/thunder probabilities to reflect the latest guidance and observations. ..Squitieri.. 08/18/2025 .PREV DISCUSSION... /ISSUED 1129 AM CDT Mon Aug 18 2025/ ...Mid MS Valley... Extensive outflow from last night's MCS currently extends from extreme southwest WI southwestward through eastern IA and north-central MO into eastern KS. This outflow has been moving quickly eastward/southeastward this morning, and this trend is expected to continue, although some slowing of its progression speed is possible over time. The downstream airmass across from southern WI and IL is characterized by dewpoints in the low to mid 70s. Mid-level lapse rates are generally poor across the region, but heating of this very moist airmass will still result in strong to very strong buoyancy (i.e. MLCAPE around 3000 J/kg) by late afternoon. Strong to severe storms are possible along this outflow as it impinges on this moist and buoyant airmass. Current trends suggest the greatest severe potential will exist this afternoon across southern WI and northern IL, where slightly stronger mid-level flow, backed surface winds, and an east-west baroclinic zone exists. Recently issued MCD 1983 addresses the short-term severe potential for this area. ...Central High Plains into the northern/central Plains... Strong heating and ample low/mid level moisture will promote the development of scattered thunderstorms by mid-afternoon over the foothills and plains of central/eastern CO. Additional isolated storms are possible farther north across western NE into the Black Hills region. Much of this area is within a corridor of modest mid-level flow on the northern periphery of the upper ridging covering the southern CONUS. Resulting modest shear may be enough for hail production with the initial development before these high-based storms trend towards outflow-dominant structures with time. These storms may persist into the evening, with an attendant threat for strong to severe gusts progressing into central NE before weakening. ...MO/AR... Clear skies and strong diurnal heating are expected across central/southern MO and much of AR. Temperatures in the upper 90s are expected, with dewpoints remaining in the mid 60s despite strong mixing. These hot and humid conditions will result in strong buoyancy this afternoon, with most guidance suggesting MLCAPE around 2000 J/kg. Shear will be weak, yielding mostly disorganized multicells, but the strongest storms will be capable of locally damaging wind gusts. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Mon Aug 18 2025 Valid 182000Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF NORTHERN ILLINOIS AND PARTS OF THE CENTRAL AND NORTHERN PLAINS... ...SUMMARY... Strong to severe storms capable of damaging winds are possible in parts of the Midwest today. Widely scattered storms with large hail and severe winds are possible in parts of the central/northern Plains through tonight. ...20Z Update... The primary change to the current Day 1 Outlook was to trim severe probabilities across portions of southern Wisconsin, where the passage of an MCS has resulted in low-level stabilization. Otherwise, only minor changes was made to severe/thunder probabilities to reflect the latest guidance and observations. ..Squitieri.. 08/18/2025 .PREV DISCUSSION... /ISSUED 1129 AM CDT Mon Aug 18 2025/ ...Mid MS Valley... Extensive outflow from last night's MCS currently extends from extreme southwest WI southwestward through eastern IA and north-central MO into eastern KS. This outflow has been moving quickly eastward/southeastward this morning, and this trend is expected to continue, although some slowing of its progression speed is possible over time. The downstream airmass across from southern WI and IL is characterized by dewpoints in the low to mid 70s. Mid-level lapse rates are generally poor across the region, but heating of this very moist airmass will still result in strong to very strong buoyancy (i.e. MLCAPE around 3000 J/kg) by late afternoon. Strong to severe storms are possible along this outflow as it impinges on this moist and buoyant airmass. Current trends suggest the greatest severe potential will exist this afternoon across southern WI and northern IL, where slightly stronger mid-level flow, backed surface winds, and an east-west baroclinic zone exists. Recently issued MCD 1983 addresses the short-term severe potential for this area. ...Central High Plains into the northern/central Plains... Strong heating and ample low/mid level moisture will promote the development of scattered thunderstorms by mid-afternoon over the foothills and plains of central/eastern CO. Additional isolated storms are possible farther north across western NE into the Black Hills region. Much of this area is within a corridor of modest mid-level flow on the northern periphery of the upper ridging covering the southern CONUS. Resulting modest shear may be enough for hail production with the initial development before these high-based storms trend towards outflow-dominant structures with time. These storms may persist into the evening, with an attendant threat for strong to severe gusts progressing into central NE before weakening. ...MO/AR... Clear skies and strong diurnal heating are expected across central/southern MO and much of AR. Temperatures in the upper 90s are expected, with dewpoints remaining in the mid 60s despite strong mixing. These hot and humid conditions will result in strong buoyancy this afternoon, with most guidance suggesting MLCAPE around 2000 J/kg. Shear will be weak, yielding mostly disorganized multicells, but the strongest storms will be capable of locally damaging wind gusts. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Mon Aug 18 2025 Valid 182000Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF NORTHERN ILLINOIS AND PARTS OF THE CENTRAL AND NORTHERN PLAINS... ...SUMMARY... Strong to severe storms capable of damaging winds are possible in parts of the Midwest today. Widely scattered storms with large hail and severe winds are possible in parts of the central/northern Plains through tonight. ...20Z Update... The primary change to the current Day 1 Outlook was to trim severe probabilities across portions of southern Wisconsin, where the passage of an MCS has resulted in low-level stabilization. Otherwise, only minor changes was made to severe/thunder probabilities to reflect the latest guidance and observations. ..Squitieri.. 08/18/2025 .PREV DISCUSSION... /ISSUED 1129 AM CDT Mon Aug 18 2025/ ...Mid MS Valley... Extensive outflow from last night's MCS currently extends from extreme southwest WI southwestward through eastern IA and north-central MO into eastern KS. This outflow has been moving quickly eastward/southeastward this morning, and this trend is expected to continue, although some slowing of its progression speed is possible over time. The downstream airmass across from southern WI and IL is characterized by dewpoints in the low to mid 70s. Mid-level lapse rates are generally poor across the region, but heating of this very moist airmass will still result in strong to very strong buoyancy (i.e. MLCAPE around 3000 J/kg) by late afternoon. Strong to severe storms are possible along this outflow as it impinges on this moist and buoyant airmass. Current trends suggest the greatest severe potential will exist this afternoon across southern WI and northern IL, where slightly stronger mid-level flow, backed surface winds, and an east-west baroclinic zone exists. Recently issued MCD 1983 addresses the short-term severe potential for this area. ...Central High Plains into the northern/central Plains... Strong heating and ample low/mid level moisture will promote the development of scattered thunderstorms by mid-afternoon over the foothills and plains of central/eastern CO. Additional isolated storms are possible farther north across western NE into the Black Hills region. Much of this area is within a corridor of modest mid-level flow on the northern periphery of the upper ridging covering the southern CONUS. Resulting modest shear may be enough for hail production with the initial development before these high-based storms trend towards outflow-dominant structures with time. These storms may persist into the evening, with an attendant threat for strong to severe gusts progressing into central NE before weakening. ...MO/AR... Clear skies and strong diurnal heating are expected across central/southern MO and much of AR. Temperatures in the upper 90s are expected, with dewpoints remaining in the mid 60s despite strong mixing. These hot and humid conditions will result in strong buoyancy this afternoon, with most guidance suggesting MLCAPE around 2000 J/kg. Shear will be weak, yielding mostly disorganized multicells, but the strongest storms will be capable of locally damaging wind gusts. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Mon Aug 18 2025 Valid 182000Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF NORTHERN ILLINOIS AND PARTS OF THE CENTRAL AND NORTHERN PLAINS... ...SUMMARY... Strong to severe storms capable of damaging winds are possible in parts of the Midwest today. Widely scattered storms with large hail and severe winds are possible in parts of the central/northern Plains through tonight. ...20Z Update... The primary change to the current Day 1 Outlook was to trim severe probabilities across portions of southern Wisconsin, where the passage of an MCS has resulted in low-level stabilization. Otherwise, only minor changes was made to severe/thunder probabilities to reflect the latest guidance and observations. ..Squitieri.. 08/18/2025 .PREV DISCUSSION... /ISSUED 1129 AM CDT Mon Aug 18 2025/ ...Mid MS Valley... Extensive outflow from last night's MCS currently extends from extreme southwest WI southwestward through eastern IA and north-central MO into eastern KS. This outflow has been moving quickly eastward/southeastward this morning, and this trend is expected to continue, although some slowing of its progression speed is possible over time. The downstream airmass across from southern WI and IL is characterized by dewpoints in the low to mid 70s. Mid-level lapse rates are generally poor across the region, but heating of this very moist airmass will still result in strong to very strong buoyancy (i.e. MLCAPE around 3000 J/kg) by late afternoon. Strong to severe storms are possible along this outflow as it impinges on this moist and buoyant airmass. Current trends suggest the greatest severe potential will exist this afternoon across southern WI and northern IL, where slightly stronger mid-level flow, backed surface winds, and an east-west baroclinic zone exists. Recently issued MCD 1983 addresses the short-term severe potential for this area. ...Central High Plains into the northern/central Plains... Strong heating and ample low/mid level moisture will promote the development of scattered thunderstorms by mid-afternoon over the foothills and plains of central/eastern CO. Additional isolated storms are possible farther north across western NE into the Black Hills region. Much of this area is within a corridor of modest mid-level flow on the northern periphery of the upper ridging covering the southern CONUS. Resulting modest shear may be enough for hail production with the initial development before these high-based storms trend towards outflow-dominant structures with time. These storms may persist into the evening, with an attendant threat for strong to severe gusts progressing into central NE before weakening. ...MO/AR... Clear skies and strong diurnal heating are expected across central/southern MO and much of AR. Temperatures in the upper 90s are expected, with dewpoints remaining in the mid 60s despite strong mixing. These hot and humid conditions will result in strong buoyancy this afternoon, with most guidance suggesting MLCAPE around 2000 J/kg. Shear will be weak, yielding mostly disorganized multicells, but the strongest storms will be capable of locally damaging wind gusts. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Mon Aug 18 2025 Valid 182000Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF NORTHERN ILLINOIS AND PARTS OF THE CENTRAL AND NORTHERN PLAINS... ...SUMMARY... Strong to severe storms capable of damaging winds are possible in parts of the Midwest today. Widely scattered storms with large hail and severe winds are possible in parts of the central/northern Plains through tonight. ...20Z Update... The primary change to the current Day 1 Outlook was to trim severe probabilities across portions of southern Wisconsin, where the passage of an MCS has resulted in low-level stabilization. Otherwise, only minor changes was made to severe/thunder probabilities to reflect the latest guidance and observations. ..Squitieri.. 08/18/2025 .PREV DISCUSSION... /ISSUED 1129 AM CDT Mon Aug 18 2025/ ...Mid MS Valley... Extensive outflow from last night's MCS currently extends from extreme southwest WI southwestward through eastern IA and north-central MO into eastern KS. This outflow has been moving quickly eastward/southeastward this morning, and this trend is expected to continue, although some slowing of its progression speed is possible over time. The downstream airmass across from southern WI and IL is characterized by dewpoints in the low to mid 70s. Mid-level lapse rates are generally poor across the region, but heating of this very moist airmass will still result in strong to very strong buoyancy (i.e. MLCAPE around 3000 J/kg) by late afternoon. Strong to severe storms are possible along this outflow as it impinges on this moist and buoyant airmass. Current trends suggest the greatest severe potential will exist this afternoon across southern WI and northern IL, where slightly stronger mid-level flow, backed surface winds, and an east-west baroclinic zone exists. Recently issued MCD 1983 addresses the short-term severe potential for this area. ...Central High Plains into the northern/central Plains... Strong heating and ample low/mid level moisture will promote the development of scattered thunderstorms by mid-afternoon over the foothills and plains of central/eastern CO. Additional isolated storms are possible farther north across western NE into the Black Hills region. Much of this area is within a corridor of modest mid-level flow on the northern periphery of the upper ridging covering the southern CONUS. Resulting modest shear may be enough for hail production with the initial development before these high-based storms trend towards outflow-dominant structures with time. These storms may persist into the evening, with an attendant threat for strong to severe gusts progressing into central NE before weakening. ...MO/AR... Clear skies and strong diurnal heating are expected across central/southern MO and much of AR. Temperatures in the upper 90s are expected, with dewpoints remaining in the mid 60s despite strong mixing. These hot and humid conditions will result in strong buoyancy this afternoon, with most guidance suggesting MLCAPE around 2000 J/kg. Shear will be weak, yielding mostly disorganized multicells, but the strongest storms will be capable of locally damaging wind gusts. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Mon Aug 18 2025 Valid 182000Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF NORTHERN ILLINOIS AND PARTS OF THE CENTRAL AND NORTHERN PLAINS... ...SUMMARY... Strong to severe storms capable of damaging winds are possible in parts of the Midwest today. Widely scattered storms with large hail and severe winds are possible in parts of the central/northern Plains through tonight. ...20Z Update... The primary change to the current Day 1 Outlook was to trim severe probabilities across portions of southern Wisconsin, where the passage of an MCS has resulted in low-level stabilization. Otherwise, only minor changes was made to severe/thunder probabilities to reflect the latest guidance and observations. ..Squitieri.. 08/18/2025 .PREV DISCUSSION... /ISSUED 1129 AM CDT Mon Aug 18 2025/ ...Mid MS Valley... Extensive outflow from last night's MCS currently extends from extreme southwest WI southwestward through eastern IA and north-central MO into eastern KS. This outflow has been moving quickly eastward/southeastward this morning, and this trend is expected to continue, although some slowing of its progression speed is possible over time. The downstream airmass across from southern WI and IL is characterized by dewpoints in the low to mid 70s. Mid-level lapse rates are generally poor across the region, but heating of this very moist airmass will still result in strong to very strong buoyancy (i.e. MLCAPE around 3000 J/kg) by late afternoon. Strong to severe storms are possible along this outflow as it impinges on this moist and buoyant airmass. Current trends suggest the greatest severe potential will exist this afternoon across southern WI and northern IL, where slightly stronger mid-level flow, backed surface winds, and an east-west baroclinic zone exists. Recently issued MCD 1983 addresses the short-term severe potential for this area. ...Central High Plains into the northern/central Plains... Strong heating and ample low/mid level moisture will promote the development of scattered thunderstorms by mid-afternoon over the foothills and plains of central/eastern CO. Additional isolated storms are possible farther north across western NE into the Black Hills region. Much of this area is within a corridor of modest mid-level flow on the northern periphery of the upper ridging covering the southern CONUS. Resulting modest shear may be enough for hail production with the initial development before these high-based storms trend towards outflow-dominant structures with time. These storms may persist into the evening, with an attendant threat for strong to severe gusts progressing into central NE before weakening. ...MO/AR... Clear skies and strong diurnal heating are expected across central/southern MO and much of AR. Temperatures in the upper 90s are expected, with dewpoints remaining in the mid 60s despite strong mixing. These hot and humid conditions will result in strong buoyancy this afternoon, with most guidance suggesting MLCAPE around 2000 J/kg. Shear will be weak, yielding mostly disorganized multicells, but the strongest storms will be capable of locally damaging wind gusts. Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0230 PM CDT Mon Aug 18 2025 Valid 201200Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN NORTHERN ND AND FAR NORTHEAST MT... ...SUMMARY... Isolated severe thunderstorms are possible Wednesday evening/night across northern North Dakota and far northeast Montana. ...Northern ND and far northeast MT... A lower-amplitude shortwave trough should progress across the Northwest on Wednesday into the northern High Plains and southern Canadian Prairies Wednesday night. This should be accompanied by an initially pronounced upper-level jet streak that should weaken late as it impinges on the northern Great Plains ridge. Stronger large-scale ascent may largely remain north of the international border until early morning Thursday. NCEP guidance suggests convection will be sparse before this timeframe with appreciable MLCIN. Non-NCEP guidance suggests potential for evening storms along the surface trough/developing front. Consensus indicates a confined low-probability severe hail/wind threat is warranted, with spatial details becoming likely to become clearer in later cycles. ...NC Outer Banks... 12Z guidance continues a westward trend to the track of Hurricane Erin. As NHC noted a larger-than-average surrounding wind field, low-probability tornado potential may overspread the Outer Banks as early as Wednesday evening with potential for outer convective band formation. However, adequate low-level SRH/hodograph curvature for a tornado risk seems likely to be displaced until Wednesday night. Any earlier arrival/farther westward track could warrant a level 1-MRGL risk highlight in later cycles. ...South-Central States... A somewhat similar setup to D2 will be displaced southward on D3 with scattered to numerous pulse-type storms expected during the afternoon to early evening. However, the convectively modified surface cold front should become more nebulous and mid-level northerlies will remain weak. In addition, the buoyancy plume should have variable pockets of weak to strong MLCAPE, especially in the wake of extensive convection on D2. Will defer to later cycles for possible microburst/localized damaging wind highlight(s). ..Grams.. 08/18/2025 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0230 PM CDT Mon Aug 18 2025 Valid 201200Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN NORTHERN ND AND FAR NORTHEAST MT... ...SUMMARY... Isolated severe thunderstorms are possible Wednesday evening/night across northern North Dakota and far northeast Montana. ...Northern ND and far northeast MT... A lower-amplitude shortwave trough should progress across the Northwest on Wednesday into the northern High Plains and southern Canadian Prairies Wednesday night. This should be accompanied by an initially pronounced upper-level jet streak that should weaken late as it impinges on the northern Great Plains ridge. Stronger large-scale ascent may largely remain north of the international border until early morning Thursday. NCEP guidance suggests convection will be sparse before this timeframe with appreciable MLCIN. Non-NCEP guidance suggests potential for evening storms along the surface trough/developing front. Consensus indicates a confined low-probability severe hail/wind threat is warranted, with spatial details becoming likely to become clearer in later cycles. ...NC Outer Banks... 12Z guidance continues a westward trend to the track of Hurricane Erin. As NHC noted a larger-than-average surrounding wind field, low-probability tornado potential may overspread the Outer Banks as early as Wednesday evening with potential for outer convective band formation. However, adequate low-level SRH/hodograph curvature for a tornado risk seems likely to be displaced until Wednesday night. Any earlier arrival/farther westward track could warrant a level 1-MRGL risk highlight in later cycles. ...South-Central States... A somewhat similar setup to D2 will be displaced southward on D3 with scattered to numerous pulse-type storms expected during the afternoon to early evening. However, the convectively modified surface cold front should become more nebulous and mid-level northerlies will remain weak. In addition, the buoyancy plume should have variable pockets of weak to strong MLCAPE, especially in the wake of extensive convection on D2. Will defer to later cycles for possible microburst/localized damaging wind highlight(s). ..Grams.. 08/18/2025 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0230 PM CDT Mon Aug 18 2025 Valid 201200Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN NORTHERN ND AND FAR NORTHEAST MT... ...SUMMARY... Isolated severe thunderstorms are possible Wednesday evening/night across northern North Dakota and far northeast Montana. ...Northern ND and far northeast MT... A lower-amplitude shortwave trough should progress across the Northwest on Wednesday into the northern High Plains and southern Canadian Prairies Wednesday night. This should be accompanied by an initially pronounced upper-level jet streak that should weaken late as it impinges on the northern Great Plains ridge. Stronger large-scale ascent may largely remain north of the international border until early morning Thursday. NCEP guidance suggests convection will be sparse before this timeframe with appreciable MLCIN. Non-NCEP guidance suggests potential for evening storms along the surface trough/developing front. Consensus indicates a confined low-probability severe hail/wind threat is warranted, with spatial details becoming likely to become clearer in later cycles. ...NC Outer Banks... 12Z guidance continues a westward trend to the track of Hurricane Erin. As NHC noted a larger-than-average surrounding wind field, low-probability tornado potential may overspread the Outer Banks as early as Wednesday evening with potential for outer convective band formation. However, adequate low-level SRH/hodograph curvature for a tornado risk seems likely to be displaced until Wednesday night. Any earlier arrival/farther westward track could warrant a level 1-MRGL risk highlight in later cycles. ...South-Central States... A somewhat similar setup to D2 will be displaced southward on D3 with scattered to numerous pulse-type storms expected during the afternoon to early evening. However, the convectively modified surface cold front should become more nebulous and mid-level northerlies will remain weak. In addition, the buoyancy plume should have variable pockets of weak to strong MLCAPE, especially in the wake of extensive convection on D2. Will defer to later cycles for possible microburst/localized damaging wind highlight(s). ..Grams.. 08/18/2025 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0230 PM CDT Mon Aug 18 2025 Valid 201200Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN NORTHERN ND AND FAR NORTHEAST MT... ...SUMMARY... Isolated severe thunderstorms are possible Wednesday evening/night across northern North Dakota and far northeast Montana. ...Northern ND and far northeast MT... A lower-amplitude shortwave trough should progress across the Northwest on Wednesday into the northern High Plains and southern Canadian Prairies Wednesday night. This should be accompanied by an initially pronounced upper-level jet streak that should weaken late as it impinges on the northern Great Plains ridge. Stronger large-scale ascent may largely remain north of the international border until early morning Thursday. NCEP guidance suggests convection will be sparse before this timeframe with appreciable MLCIN. Non-NCEP guidance suggests potential for evening storms along the surface trough/developing front. Consensus indicates a confined low-probability severe hail/wind threat is warranted, with spatial details becoming likely to become clearer in later cycles. ...NC Outer Banks... 12Z guidance continues a westward trend to the track of Hurricane Erin. As NHC noted a larger-than-average surrounding wind field, low-probability tornado potential may overspread the Outer Banks as early as Wednesday evening with potential for outer convective band formation. However, adequate low-level SRH/hodograph curvature for a tornado risk seems likely to be displaced until Wednesday night. Any earlier arrival/farther westward track could warrant a level 1-MRGL risk highlight in later cycles. ...South-Central States... A somewhat similar setup to D2 will be displaced southward on D3 with scattered to numerous pulse-type storms expected during the afternoon to early evening. However, the convectively modified surface cold front should become more nebulous and mid-level northerlies will remain weak. In addition, the buoyancy plume should have variable pockets of weak to strong MLCAPE, especially in the wake of extensive convection on D2. Will defer to later cycles for possible microburst/localized damaging wind highlight(s). ..Grams.. 08/18/2025 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0230 PM CDT Mon Aug 18 2025 Valid 201200Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN NORTHERN ND AND FAR NORTHEAST MT... ...SUMMARY... Isolated severe thunderstorms are possible Wednesday evening/night across northern North Dakota and far northeast Montana. ...Northern ND and far northeast MT... A lower-amplitude shortwave trough should progress across the Northwest on Wednesday into the northern High Plains and southern Canadian Prairies Wednesday night. This should be accompanied by an initially pronounced upper-level jet streak that should weaken late as it impinges on the northern Great Plains ridge. Stronger large-scale ascent may largely remain north of the international border until early morning Thursday. NCEP guidance suggests convection will be sparse before this timeframe with appreciable MLCIN. Non-NCEP guidance suggests potential for evening storms along the surface trough/developing front. Consensus indicates a confined low-probability severe hail/wind threat is warranted, with spatial details becoming likely to become clearer in later cycles. ...NC Outer Banks... 12Z guidance continues a westward trend to the track of Hurricane Erin. As NHC noted a larger-than-average surrounding wind field, low-probability tornado potential may overspread the Outer Banks as early as Wednesday evening with potential for outer convective band formation. However, adequate low-level SRH/hodograph curvature for a tornado risk seems likely to be displaced until Wednesday night. Any earlier arrival/farther westward track could warrant a level 1-MRGL risk highlight in later cycles. ...South-Central States... A somewhat similar setup to D2 will be displaced southward on D3 with scattered to numerous pulse-type storms expected during the afternoon to early evening. However, the convectively modified surface cold front should become more nebulous and mid-level northerlies will remain weak. In addition, the buoyancy plume should have variable pockets of weak to strong MLCAPE, especially in the wake of extensive convection on D2. Will defer to later cycles for possible microburst/localized damaging wind highlight(s). ..Grams.. 08/18/2025 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0230 PM CDT Mon Aug 18 2025 Valid 201200Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN NORTHERN ND AND FAR NORTHEAST MT... ...SUMMARY... Isolated severe thunderstorms are possible Wednesday evening/night across northern North Dakota and far northeast Montana. ...Northern ND and far northeast MT... A lower-amplitude shortwave trough should progress across the Northwest on Wednesday into the northern High Plains and southern Canadian Prairies Wednesday night. This should be accompanied by an initially pronounced upper-level jet streak that should weaken late as it impinges on the northern Great Plains ridge. Stronger large-scale ascent may largely remain north of the international border until early morning Thursday. NCEP guidance suggests convection will be sparse before this timeframe with appreciable MLCIN. Non-NCEP guidance suggests potential for evening storms along the surface trough/developing front. Consensus indicates a confined low-probability severe hail/wind threat is warranted, with spatial details becoming likely to become clearer in later cycles. ...NC Outer Banks... 12Z guidance continues a westward trend to the track of Hurricane Erin. As NHC noted a larger-than-average surrounding wind field, low-probability tornado potential may overspread the Outer Banks as early as Wednesday evening with potential for outer convective band formation. However, adequate low-level SRH/hodograph curvature for a tornado risk seems likely to be displaced until Wednesday night. Any earlier arrival/farther westward track could warrant a level 1-MRGL risk highlight in later cycles. ...South-Central States... A somewhat similar setup to D2 will be displaced southward on D3 with scattered to numerous pulse-type storms expected during the afternoon to early evening. However, the convectively modified surface cold front should become more nebulous and mid-level northerlies will remain weak. In addition, the buoyancy plume should have variable pockets of weak to strong MLCAPE, especially in the wake of extensive convection on D2. Will defer to later cycles for possible microburst/localized damaging wind highlight(s). ..Grams.. 08/18/2025 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0230 PM CDT Mon Aug 18 2025 Valid 201200Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN NORTHERN ND AND FAR NORTHEAST MT... ...SUMMARY... Isolated severe thunderstorms are possible Wednesday evening/night across northern North Dakota and far northeast Montana. ...Northern ND and far northeast MT... A lower-amplitude shortwave trough should progress across the Northwest on Wednesday into the northern High Plains and southern Canadian Prairies Wednesday night. This should be accompanied by an initially pronounced upper-level jet streak that should weaken late as it impinges on the northern Great Plains ridge. Stronger large-scale ascent may largely remain north of the international border until early morning Thursday. NCEP guidance suggests convection will be sparse before this timeframe with appreciable MLCIN. Non-NCEP guidance suggests potential for evening storms along the surface trough/developing front. Consensus indicates a confined low-probability severe hail/wind threat is warranted, with spatial details becoming likely to become clearer in later cycles. ...NC Outer Banks... 12Z guidance continues a westward trend to the track of Hurricane Erin. As NHC noted a larger-than-average surrounding wind field, low-probability tornado potential may overspread the Outer Banks as early as Wednesday evening with potential for outer convective band formation. However, adequate low-level SRH/hodograph curvature for a tornado risk seems likely to be displaced until Wednesday night. Any earlier arrival/farther westward track could warrant a level 1-MRGL risk highlight in later cycles. ...South-Central States... A somewhat similar setup to D2 will be displaced southward on D3 with scattered to numerous pulse-type storms expected during the afternoon to early evening. However, the convectively modified surface cold front should become more nebulous and mid-level northerlies will remain weak. In addition, the buoyancy plume should have variable pockets of weak to strong MLCAPE, especially in the wake of extensive convection on D2. Will defer to later cycles for possible microburst/localized damaging wind highlight(s). ..Grams.. 08/18/2025 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0230 PM CDT Mon Aug 18 2025 Valid 201200Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN NORTHERN ND AND FAR NORTHEAST MT... ...SUMMARY... Isolated severe thunderstorms are possible Wednesday evening/night across northern North Dakota and far northeast Montana. ...Northern ND and far northeast MT... A lower-amplitude shortwave trough should progress across the Northwest on Wednesday into the northern High Plains and southern Canadian Prairies Wednesday night. This should be accompanied by an initially pronounced upper-level jet streak that should weaken late as it impinges on the northern Great Plains ridge. Stronger large-scale ascent may largely remain north of the international border until early morning Thursday. NCEP guidance suggests convection will be sparse before this timeframe with appreciable MLCIN. Non-NCEP guidance suggests potential for evening storms along the surface trough/developing front. Consensus indicates a confined low-probability severe hail/wind threat is warranted, with spatial details becoming likely to become clearer in later cycles. ...NC Outer Banks... 12Z guidance continues a westward trend to the track of Hurricane Erin. As NHC noted a larger-than-average surrounding wind field, low-probability tornado potential may overspread the Outer Banks as early as Wednesday evening with potential for outer convective band formation. However, adequate low-level SRH/hodograph curvature for a tornado risk seems likely to be displaced until Wednesday night. Any earlier arrival/farther westward track could warrant a level 1-MRGL risk highlight in later cycles. ...South-Central States... A somewhat similar setup to D2 will be displaced southward on D3 with scattered to numerous pulse-type storms expected during the afternoon to early evening. However, the convectively modified surface cold front should become more nebulous and mid-level northerlies will remain weak. In addition, the buoyancy plume should have variable pockets of weak to strong MLCAPE, especially in the wake of extensive convection on D2. Will defer to later cycles for possible microburst/localized damaging wind highlight(s). ..Grams.. 08/18/2025 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0230 PM CDT Mon Aug 18 2025 Valid 201200Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN NORTHERN ND AND FAR NORTHEAST MT... ...SUMMARY... Isolated severe thunderstorms are possible Wednesday evening/night across northern North Dakota and far northeast Montana. ...Northern ND and far northeast MT... A lower-amplitude shortwave trough should progress across the Northwest on Wednesday into the northern High Plains and southern Canadian Prairies Wednesday night. This should be accompanied by an initially pronounced upper-level jet streak that should weaken late as it impinges on the northern Great Plains ridge. Stronger large-scale ascent may largely remain north of the international border until early morning Thursday. NCEP guidance suggests convection will be sparse before this timeframe with appreciable MLCIN. Non-NCEP guidance suggests potential for evening storms along the surface trough/developing front. Consensus indicates a confined low-probability severe hail/wind threat is warranted, with spatial details becoming likely to become clearer in later cycles. ...NC Outer Banks... 12Z guidance continues a westward trend to the track of Hurricane Erin. As NHC noted a larger-than-average surrounding wind field, low-probability tornado potential may overspread the Outer Banks as early as Wednesday evening with potential for outer convective band formation. However, adequate low-level SRH/hodograph curvature for a tornado risk seems likely to be displaced until Wednesday night. Any earlier arrival/farther westward track could warrant a level 1-MRGL risk highlight in later cycles. ...South-Central States... A somewhat similar setup to D2 will be displaced southward on D3 with scattered to numerous pulse-type storms expected during the afternoon to early evening. However, the convectively modified surface cold front should become more nebulous and mid-level northerlies will remain weak. In addition, the buoyancy plume should have variable pockets of weak to strong MLCAPE, especially in the wake of extensive convection on D2. Will defer to later cycles for possible microburst/localized damaging wind highlight(s). ..Grams.. 08/18/2025 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0230 PM CDT Mon Aug 18 2025 Valid 201200Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN NORTHERN ND AND FAR NORTHEAST MT... ...SUMMARY... Isolated severe thunderstorms are possible Wednesday evening/night across northern North Dakota and far northeast Montana. ...Northern ND and far northeast MT... A lower-amplitude shortwave trough should progress across the Northwest on Wednesday into the northern High Plains and southern Canadian Prairies Wednesday night. This should be accompanied by an initially pronounced upper-level jet streak that should weaken late as it impinges on the northern Great Plains ridge. Stronger large-scale ascent may largely remain north of the international border until early morning Thursday. NCEP guidance suggests convection will be sparse before this timeframe with appreciable MLCIN. Non-NCEP guidance suggests potential for evening storms along the surface trough/developing front. Consensus indicates a confined low-probability severe hail/wind threat is warranted, with spatial details becoming likely to become clearer in later cycles. ...NC Outer Banks... 12Z guidance continues a westward trend to the track of Hurricane Erin. As NHC noted a larger-than-average surrounding wind field, low-probability tornado potential may overspread the Outer Banks as early as Wednesday evening with potential for outer convective band formation. However, adequate low-level SRH/hodograph curvature for a tornado risk seems likely to be displaced until Wednesday night. Any earlier arrival/farther westward track could warrant a level 1-MRGL risk highlight in later cycles. ...South-Central States... A somewhat similar setup to D2 will be displaced southward on D3 with scattered to numerous pulse-type storms expected during the afternoon to early evening. However, the convectively modified surface cold front should become more nebulous and mid-level northerlies will remain weak. In addition, the buoyancy plume should have variable pockets of weak to strong MLCAPE, especially in the wake of extensive convection on D2. Will defer to later cycles for possible microburst/localized damaging wind highlight(s). ..Grams.. 08/18/2025 Read more