SPC May 12, 2025 1630 UTC Day 1 Convective Outlook

3 months 1 week ago
SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Mon May 12 2025 Valid 121630Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN MONTANA AND NORTHWEST NORTH DAKOTA... ...SUMMARY... Isolated severe thunderstorms are possible across parts of the Southeast today, where a tornado or two, localized damaging winds, and hail could occur. Isolated severe wind gusts are also possible in northeast Montana to northwest North Dakota around early evening. ...Southeast... Vertically stacked cyclone persists over the Mid-South this morning. Expectation is for this system to become more progressive today, ejecting into western TN by early tomorrow morning. A moist airmass remains in place downstream of this cyclone across the Southeast, and numerous showers and thunderstorms are currently ongoing within the warm conveyor of this system from FL into GA and the Carolina. Moderate southwesterly/southerly will persist within this warm sector, and effective shear should be sufficient for multicell clusters and transient updraft rotation. However, only modest destabilization is anticipated across much of the region, limiting the overall severe potential. Expectation is for occasionally strong storms in areas of sufficient destabilization, with damaging downbursts and hail as the primary risk. A corridor of greater severe potential could be developing across southern GA and northern FL where some heating is occurring. ...Northeast Montana/northwest North Dakota... Deep shortwave trough will continue to push eastward across the Pacific Northwest today, with associated southwesterly flow aloft extending from northern CA into the northern High Plains. Deeply mixed thermodynamic profiles are expected across the region as the airmass destabilizes this afternoon. Isolated thunderstorms are most probable from mid-afternoon into evening with development near/behind an eastward-advancing front. Convective coverage off the higher terrain of southern Montana should be less than in recent days. However, the potential will still exist for a few dry microbursts producing localized severe-caliber wind gusts as the storms move off the terrain into more of eastern MT. ..Mosier/Halbert.. 05/12/2025 Read more

SPC May 12, 2025 1630 UTC Day 1 Convective Outlook

3 months 1 week ago
SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Mon May 12 2025 Valid 121630Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN MONTANA AND NORTHWEST NORTH DAKOTA... ...SUMMARY... Isolated severe thunderstorms are possible across parts of the Southeast today, where a tornado or two, localized damaging winds, and hail could occur. Isolated severe wind gusts are also possible in northeast Montana to northwest North Dakota around early evening. ...Southeast... Vertically stacked cyclone persists over the Mid-South this morning. Expectation is for this system to become more progressive today, ejecting into western TN by early tomorrow morning. A moist airmass remains in place downstream of this cyclone across the Southeast, and numerous showers and thunderstorms are currently ongoing within the warm conveyor of this system from FL into GA and the Carolina. Moderate southwesterly/southerly will persist within this warm sector, and effective shear should be sufficient for multicell clusters and transient updraft rotation. However, only modest destabilization is anticipated across much of the region, limiting the overall severe potential. Expectation is for occasionally strong storms in areas of sufficient destabilization, with damaging downbursts and hail as the primary risk. A corridor of greater severe potential could be developing across southern GA and northern FL where some heating is occurring. ...Northeast Montana/northwest North Dakota... Deep shortwave trough will continue to push eastward across the Pacific Northwest today, with associated southwesterly flow aloft extending from northern CA into the northern High Plains. Deeply mixed thermodynamic profiles are expected across the region as the airmass destabilizes this afternoon. Isolated thunderstorms are most probable from mid-afternoon into evening with development near/behind an eastward-advancing front. Convective coverage off the higher terrain of southern Montana should be less than in recent days. However, the potential will still exist for a few dry microbursts producing localized severe-caliber wind gusts as the storms move off the terrain into more of eastern MT. ..Mosier/Halbert.. 05/12/2025 Read more

SPC May 12, 2025 1630 UTC Day 1 Convective Outlook

3 months 1 week ago
SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Mon May 12 2025 Valid 121630Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN MONTANA AND NORTHWEST NORTH DAKOTA... ...SUMMARY... Isolated severe thunderstorms are possible across parts of the Southeast today, where a tornado or two, localized damaging winds, and hail could occur. Isolated severe wind gusts are also possible in northeast Montana to northwest North Dakota around early evening. ...Southeast... Vertically stacked cyclone persists over the Mid-South this morning. Expectation is for this system to become more progressive today, ejecting into western TN by early tomorrow morning. A moist airmass remains in place downstream of this cyclone across the Southeast, and numerous showers and thunderstorms are currently ongoing within the warm conveyor of this system from FL into GA and the Carolina. Moderate southwesterly/southerly will persist within this warm sector, and effective shear should be sufficient for multicell clusters and transient updraft rotation. However, only modest destabilization is anticipated across much of the region, limiting the overall severe potential. Expectation is for occasionally strong storms in areas of sufficient destabilization, with damaging downbursts and hail as the primary risk. A corridor of greater severe potential could be developing across southern GA and northern FL where some heating is occurring. ...Northeast Montana/northwest North Dakota... Deep shortwave trough will continue to push eastward across the Pacific Northwest today, with associated southwesterly flow aloft extending from northern CA into the northern High Plains. Deeply mixed thermodynamic profiles are expected across the region as the airmass destabilizes this afternoon. Isolated thunderstorms are most probable from mid-afternoon into evening with development near/behind an eastward-advancing front. Convective coverage off the higher terrain of southern Montana should be less than in recent days. However, the potential will still exist for a few dry microbursts producing localized severe-caliber wind gusts as the storms move off the terrain into more of eastern MT. ..Mosier/Halbert.. 05/12/2025 Read more

SPC May 12, 2025 1630 UTC Day 1 Convective Outlook

3 months 1 week ago
SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Mon May 12 2025 Valid 121630Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN MONTANA AND NORTHWEST NORTH DAKOTA... ...SUMMARY... Isolated severe thunderstorms are possible across parts of the Southeast today, where a tornado or two, localized damaging winds, and hail could occur. Isolated severe wind gusts are also possible in northeast Montana to northwest North Dakota around early evening. ...Southeast... Vertically stacked cyclone persists over the Mid-South this morning. Expectation is for this system to become more progressive today, ejecting into western TN by early tomorrow morning. A moist airmass remains in place downstream of this cyclone across the Southeast, and numerous showers and thunderstorms are currently ongoing within the warm conveyor of this system from FL into GA and the Carolina. Moderate southwesterly/southerly will persist within this warm sector, and effective shear should be sufficient for multicell clusters and transient updraft rotation. However, only modest destabilization is anticipated across much of the region, limiting the overall severe potential. Expectation is for occasionally strong storms in areas of sufficient destabilization, with damaging downbursts and hail as the primary risk. A corridor of greater severe potential could be developing across southern GA and northern FL where some heating is occurring. ...Northeast Montana/northwest North Dakota... Deep shortwave trough will continue to push eastward across the Pacific Northwest today, with associated southwesterly flow aloft extending from northern CA into the northern High Plains. Deeply mixed thermodynamic profiles are expected across the region as the airmass destabilizes this afternoon. Isolated thunderstorms are most probable from mid-afternoon into evening with development near/behind an eastward-advancing front. Convective coverage off the higher terrain of southern Montana should be less than in recent days. However, the potential will still exist for a few dry microbursts producing localized severe-caliber wind gusts as the storms move off the terrain into more of eastern MT. ..Mosier/Halbert.. 05/12/2025 Read more

SPC May 12, 2025 1630 UTC Day 1 Convective Outlook

3 months 1 week ago
SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Mon May 12 2025 Valid 121630Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN MONTANA AND NORTHWEST NORTH DAKOTA... ...SUMMARY... Isolated severe thunderstorms are possible across parts of the Southeast today, where a tornado or two, localized damaging winds, and hail could occur. Isolated severe wind gusts are also possible in northeast Montana to northwest North Dakota around early evening. ...Southeast... Vertically stacked cyclone persists over the Mid-South this morning. Expectation is for this system to become more progressive today, ejecting into western TN by early tomorrow morning. A moist airmass remains in place downstream of this cyclone across the Southeast, and numerous showers and thunderstorms are currently ongoing within the warm conveyor of this system from FL into GA and the Carolina. Moderate southwesterly/southerly will persist within this warm sector, and effective shear should be sufficient for multicell clusters and transient updraft rotation. However, only modest destabilization is anticipated across much of the region, limiting the overall severe potential. Expectation is for occasionally strong storms in areas of sufficient destabilization, with damaging downbursts and hail as the primary risk. A corridor of greater severe potential could be developing across southern GA and northern FL where some heating is occurring. ...Northeast Montana/northwest North Dakota... Deep shortwave trough will continue to push eastward across the Pacific Northwest today, with associated southwesterly flow aloft extending from northern CA into the northern High Plains. Deeply mixed thermodynamic profiles are expected across the region as the airmass destabilizes this afternoon. Isolated thunderstorms are most probable from mid-afternoon into evening with development near/behind an eastward-advancing front. Convective coverage off the higher terrain of southern Montana should be less than in recent days. However, the potential will still exist for a few dry microbursts producing localized severe-caliber wind gusts as the storms move off the terrain into more of eastern MT. ..Mosier/Halbert.. 05/12/2025 Read more

SPC May 12, 2025 1630 UTC Day 1 Convective Outlook

3 months 1 week ago
SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Mon May 12 2025 Valid 121630Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN MONTANA AND NORTHWEST NORTH DAKOTA... ...SUMMARY... Isolated severe thunderstorms are possible across parts of the Southeast today, where a tornado or two, localized damaging winds, and hail could occur. Isolated severe wind gusts are also possible in northeast Montana to northwest North Dakota around early evening. ...Southeast... Vertically stacked cyclone persists over the Mid-South this morning. Expectation is for this system to become more progressive today, ejecting into western TN by early tomorrow morning. A moist airmass remains in place downstream of this cyclone across the Southeast, and numerous showers and thunderstorms are currently ongoing within the warm conveyor of this system from FL into GA and the Carolina. Moderate southwesterly/southerly will persist within this warm sector, and effective shear should be sufficient for multicell clusters and transient updraft rotation. However, only modest destabilization is anticipated across much of the region, limiting the overall severe potential. Expectation is for occasionally strong storms in areas of sufficient destabilization, with damaging downbursts and hail as the primary risk. A corridor of greater severe potential could be developing across southern GA and northern FL where some heating is occurring. ...Northeast Montana/northwest North Dakota... Deep shortwave trough will continue to push eastward across the Pacific Northwest today, with associated southwesterly flow aloft extending from northern CA into the northern High Plains. Deeply mixed thermodynamic profiles are expected across the region as the airmass destabilizes this afternoon. Isolated thunderstorms are most probable from mid-afternoon into evening with development near/behind an eastward-advancing front. Convective coverage off the higher terrain of southern Montana should be less than in recent days. However, the potential will still exist for a few dry microbursts producing localized severe-caliber wind gusts as the storms move off the terrain into more of eastern MT. ..Mosier/Halbert.. 05/12/2025 Read more

SPC May 12, 2025 1300 UTC Day 1 Convective Outlook

3 months 1 week ago
SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0741 AM CDT Mon May 12 2025 Valid 121300Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN MONTANA AND NORTHWEST NORTH DAKOTA... ...SUMMARY... Isolated severe thunderstorms are possible across parts of the Southeast today, where a tornado or two, localized damaging winds, and hail could occur. Isolated severe wind gusts are also possible in northeast Montana to northwest North Dakota around early evening. ...Southeast States... The persistent vertically stacked mid/upper low that has been nearly stationary over the Sabine Valley/Lower Mississippi River Valley will finally accelerate northeastward towards western Tennessee through tonight. A jetlet of cyclonically curved mid-level southerlies over the northeast Gulf and Florida Panhandle will dampen somewhat as it becomes centered on north Florida to southeast Georgia vicinity this afternoon. More probable diurnal thunderstorm development is anticipated from the left-exit region of this jetlet westward towards the cold-core of the stacked low. Deep-layer vertical shear will relax with westward extent, yielding more of a pulse strong-storm environment from Middle Tennessee to western Alabama and Mississippi. Despite the meridional deep-layer wind profile, effective shear should be sufficient for multicell clusters and transient updraft rotation centered on eastern Alabama and Georgia into north Florida. Pockets of modest buoyancy should support a mix of small to marginally severe hail and strong gusts capable of isolated damaging winds. Along the eastern periphery of this activity, a tornado or two is possible where there remains some overlap with the western belt of enhanced low-level flow, including South Carolina into both western and near-coastal North Carolina. Farther south, a more nebulous convective scenario is anticipated amid extensive ongoing convection across the Florida Peninsula and Keys. Guidance differs markedly with the degree of destabilization, as adequate boundary-layer heating will be required amid poor mid-level lapse rates near 5 C/km. But some guidance suggests south-central/southern Florida has the best chance at recovery by afternoon, although low-level winds will tend to be veering with a likely diminishing trend of low-level SRH. ...Northeast Montana/northwest North Dakota... Another day of rather deeply mixed thermodynamic profiles is expected across the region. Isolated thunderstorms are most probable from mid-afternoon into evening with development near/behind an eastward-advancing front. Overall convective coverage off the higher terrain of southern Montana should be substantially less than in recent days, amid deep-layer southwesterly wind profiles. The potential will exist for a few dry microbursts producing localized severe-caliber wind gusts. ..Guyer/Dean.. 05/12/2025 Read more

SPC May 12, 2025 1300 UTC Day 1 Convective Outlook

3 months 1 week ago
SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0741 AM CDT Mon May 12 2025 Valid 121300Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN MONTANA AND NORTHWEST NORTH DAKOTA... ...SUMMARY... Isolated severe thunderstorms are possible across parts of the Southeast today, where a tornado or two, localized damaging winds, and hail could occur. Isolated severe wind gusts are also possible in northeast Montana to northwest North Dakota around early evening. ...Southeast States... The persistent vertically stacked mid/upper low that has been nearly stationary over the Sabine Valley/Lower Mississippi River Valley will finally accelerate northeastward towards western Tennessee through tonight. A jetlet of cyclonically curved mid-level southerlies over the northeast Gulf and Florida Panhandle will dampen somewhat as it becomes centered on north Florida to southeast Georgia vicinity this afternoon. More probable diurnal thunderstorm development is anticipated from the left-exit region of this jetlet westward towards the cold-core of the stacked low. Deep-layer vertical shear will relax with westward extent, yielding more of a pulse strong-storm environment from Middle Tennessee to western Alabama and Mississippi. Despite the meridional deep-layer wind profile, effective shear should be sufficient for multicell clusters and transient updraft rotation centered on eastern Alabama and Georgia into north Florida. Pockets of modest buoyancy should support a mix of small to marginally severe hail and strong gusts capable of isolated damaging winds. Along the eastern periphery of this activity, a tornado or two is possible where there remains some overlap with the western belt of enhanced low-level flow, including South Carolina into both western and near-coastal North Carolina. Farther south, a more nebulous convective scenario is anticipated amid extensive ongoing convection across the Florida Peninsula and Keys. Guidance differs markedly with the degree of destabilization, as adequate boundary-layer heating will be required amid poor mid-level lapse rates near 5 C/km. But some guidance suggests south-central/southern Florida has the best chance at recovery by afternoon, although low-level winds will tend to be veering with a likely diminishing trend of low-level SRH. ...Northeast Montana/northwest North Dakota... Another day of rather deeply mixed thermodynamic profiles is expected across the region. Isolated thunderstorms are most probable from mid-afternoon into evening with development near/behind an eastward-advancing front. Overall convective coverage off the higher terrain of southern Montana should be substantially less than in recent days, amid deep-layer southwesterly wind profiles. The potential will exist for a few dry microbursts producing localized severe-caliber wind gusts. ..Guyer/Dean.. 05/12/2025 Read more

SPC May 12, 2025 1300 UTC Day 1 Convective Outlook

3 months 1 week ago
SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0741 AM CDT Mon May 12 2025 Valid 121300Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN MONTANA AND NORTHWEST NORTH DAKOTA... ...SUMMARY... Isolated severe thunderstorms are possible across parts of the Southeast today, where a tornado or two, localized damaging winds, and hail could occur. Isolated severe wind gusts are also possible in northeast Montana to northwest North Dakota around early evening. ...Southeast States... The persistent vertically stacked mid/upper low that has been nearly stationary over the Sabine Valley/Lower Mississippi River Valley will finally accelerate northeastward towards western Tennessee through tonight. A jetlet of cyclonically curved mid-level southerlies over the northeast Gulf and Florida Panhandle will dampen somewhat as it becomes centered on north Florida to southeast Georgia vicinity this afternoon. More probable diurnal thunderstorm development is anticipated from the left-exit region of this jetlet westward towards the cold-core of the stacked low. Deep-layer vertical shear will relax with westward extent, yielding more of a pulse strong-storm environment from Middle Tennessee to western Alabama and Mississippi. Despite the meridional deep-layer wind profile, effective shear should be sufficient for multicell clusters and transient updraft rotation centered on eastern Alabama and Georgia into north Florida. Pockets of modest buoyancy should support a mix of small to marginally severe hail and strong gusts capable of isolated damaging winds. Along the eastern periphery of this activity, a tornado or two is possible where there remains some overlap with the western belt of enhanced low-level flow, including South Carolina into both western and near-coastal North Carolina. Farther south, a more nebulous convective scenario is anticipated amid extensive ongoing convection across the Florida Peninsula and Keys. Guidance differs markedly with the degree of destabilization, as adequate boundary-layer heating will be required amid poor mid-level lapse rates near 5 C/km. But some guidance suggests south-central/southern Florida has the best chance at recovery by afternoon, although low-level winds will tend to be veering with a likely diminishing trend of low-level SRH. ...Northeast Montana/northwest North Dakota... Another day of rather deeply mixed thermodynamic profiles is expected across the region. Isolated thunderstorms are most probable from mid-afternoon into evening with development near/behind an eastward-advancing front. Overall convective coverage off the higher terrain of southern Montana should be substantially less than in recent days, amid deep-layer southwesterly wind profiles. The potential will exist for a few dry microbursts producing localized severe-caliber wind gusts. ..Guyer/Dean.. 05/12/2025 Read more

SPC May 12, 2025 1300 UTC Day 1 Convective Outlook

3 months 1 week ago
SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0741 AM CDT Mon May 12 2025 Valid 121300Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN MONTANA AND NORTHWEST NORTH DAKOTA... ...SUMMARY... Isolated severe thunderstorms are possible across parts of the Southeast today, where a tornado or two, localized damaging winds, and hail could occur. Isolated severe wind gusts are also possible in northeast Montana to northwest North Dakota around early evening. ...Southeast States... The persistent vertically stacked mid/upper low that has been nearly stationary over the Sabine Valley/Lower Mississippi River Valley will finally accelerate northeastward towards western Tennessee through tonight. A jetlet of cyclonically curved mid-level southerlies over the northeast Gulf and Florida Panhandle will dampen somewhat as it becomes centered on north Florida to southeast Georgia vicinity this afternoon. More probable diurnal thunderstorm development is anticipated from the left-exit region of this jetlet westward towards the cold-core of the stacked low. Deep-layer vertical shear will relax with westward extent, yielding more of a pulse strong-storm environment from Middle Tennessee to western Alabama and Mississippi. Despite the meridional deep-layer wind profile, effective shear should be sufficient for multicell clusters and transient updraft rotation centered on eastern Alabama and Georgia into north Florida. Pockets of modest buoyancy should support a mix of small to marginally severe hail and strong gusts capable of isolated damaging winds. Along the eastern periphery of this activity, a tornado or two is possible where there remains some overlap with the western belt of enhanced low-level flow, including South Carolina into both western and near-coastal North Carolina. Farther south, a more nebulous convective scenario is anticipated amid extensive ongoing convection across the Florida Peninsula and Keys. Guidance differs markedly with the degree of destabilization, as adequate boundary-layer heating will be required amid poor mid-level lapse rates near 5 C/km. But some guidance suggests south-central/southern Florida has the best chance at recovery by afternoon, although low-level winds will tend to be veering with a likely diminishing trend of low-level SRH. ...Northeast Montana/northwest North Dakota... Another day of rather deeply mixed thermodynamic profiles is expected across the region. Isolated thunderstorms are most probable from mid-afternoon into evening with development near/behind an eastward-advancing front. Overall convective coverage off the higher terrain of southern Montana should be substantially less than in recent days, amid deep-layer southwesterly wind profiles. The potential will exist for a few dry microbursts producing localized severe-caliber wind gusts. ..Guyer/Dean.. 05/12/2025 Read more

SPC May 12, 2025 Day 4-8 Severe Weather Outlook

3 months 1 week ago
Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0359 AM CDT Mon May 12 2025 Valid 151200Z - 201200Z ...DISCUSSION... An active period of severe weather is anticipated through early next week based on recent trends in long-range guidance. A transition to a progressive upper-level regime is expected over the next seven days as a series of upper waves traverse the CONUS with favorable wavelengths for air mass/moisture recovery into central portions of the CONUS. Although both the GFS and ECMWF (and their respective ensemble families) show similar synoptic evolutions through the extended period, predictability in any severe threat currently appears greatest on D4/Thursday and D5/Friday. ...D4/Thursday... The upper-level trough currently over the Pacific Northwest is forecast to eject into the upper MS River Valley through the day Thursday with an attendant surface low deepening across the upper MS Valley. A Pacific front is forecast to push east into an expanding warm sector that should span from the MS River into the upper Great Lakes and OH River Valley. Strong mid-level flow orthogonal to the front should generally promote discrete/semi-discrete convection by late afternoon on the eastern fringe of a stout EML. The consistent signal for QPF within the warm sector coincident with 50-60 knot mid-level flow and the intensifying nature of the synoptic low suggests that a widespread severe weather event is possible and may expand further east than depicted in previous forecasts. Despite these trends, regional discrepancies among guidance limit confidence in where the more robust severe corridors will become established. Notable factors limiting confidence are the potential for strong capping across much of the OH Valley and a faster progression of the surface low/front in recent GFS/GEFS solutions (which typically exhibit a fast bias at this range). ...D5/Friday... The Pacific front/outflow associated with D4/Thursday's convection is expected to stall across the lower OH Valley/mid-MS Valley before gradually returning north as an effective warm front on Friday. Ensemble guidance shows a reasonably strong signal for dewpoints in the mid/upper 60s (potentially into the low 70s) along and south of this boundary by peak heating. A mid-level impulse propagating over the region should maintain elongated hodographs and provide sufficient lift for thunderstorm development along the boundary. This synoptic regime suggests that one or more organized clusters/linear segments may propagate along the boundary and into parts of the mid-MS Valley, lower OH Valley, and potentially into the TN Valley. Given the thermodynamic and kinematic environment forecast by ensemble guidance, such a cluster/line will likely pose a severe threat. A 15% risk area has been introduced where the QPF signal associated with this regime has been most consistent over recent model runs, but further forecast refinements are expected. Read more

SPC May 12, 2025 Day 4-8 Severe Weather Outlook

3 months 1 week ago
Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0359 AM CDT Mon May 12 2025 Valid 151200Z - 201200Z ...DISCUSSION... An active period of severe weather is anticipated through early next week based on recent trends in long-range guidance. A transition to a progressive upper-level regime is expected over the next seven days as a series of upper waves traverse the CONUS with favorable wavelengths for air mass/moisture recovery into central portions of the CONUS. Although both the GFS and ECMWF (and their respective ensemble families) show similar synoptic evolutions through the extended period, predictability in any severe threat currently appears greatest on D4/Thursday and D5/Friday. ...D4/Thursday... The upper-level trough currently over the Pacific Northwest is forecast to eject into the upper MS River Valley through the day Thursday with an attendant surface low deepening across the upper MS Valley. A Pacific front is forecast to push east into an expanding warm sector that should span from the MS River into the upper Great Lakes and OH River Valley. Strong mid-level flow orthogonal to the front should generally promote discrete/semi-discrete convection by late afternoon on the eastern fringe of a stout EML. The consistent signal for QPF within the warm sector coincident with 50-60 knot mid-level flow and the intensifying nature of the synoptic low suggests that a widespread severe weather event is possible and may expand further east than depicted in previous forecasts. Despite these trends, regional discrepancies among guidance limit confidence in where the more robust severe corridors will become established. Notable factors limiting confidence are the potential for strong capping across much of the OH Valley and a faster progression of the surface low/front in recent GFS/GEFS solutions (which typically exhibit a fast bias at this range). ...D5/Friday... The Pacific front/outflow associated with D4/Thursday's convection is expected to stall across the lower OH Valley/mid-MS Valley before gradually returning north as an effective warm front on Friday. Ensemble guidance shows a reasonably strong signal for dewpoints in the mid/upper 60s (potentially into the low 70s) along and south of this boundary by peak heating. A mid-level impulse propagating over the region should maintain elongated hodographs and provide sufficient lift for thunderstorm development along the boundary. This synoptic regime suggests that one or more organized clusters/linear segments may propagate along the boundary and into parts of the mid-MS Valley, lower OH Valley, and potentially into the TN Valley. Given the thermodynamic and kinematic environment forecast by ensemble guidance, such a cluster/line will likely pose a severe threat. A 15% risk area has been introduced where the QPF signal associated with this regime has been most consistent over recent model runs, but further forecast refinements are expected. Read more

SPC May 12, 2025 Day 4-8 Severe Weather Outlook

3 months 1 week ago
Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0359 AM CDT Mon May 12 2025 Valid 151200Z - 201200Z ...DISCUSSION... An active period of severe weather is anticipated through early next week based on recent trends in long-range guidance. A transition to a progressive upper-level regime is expected over the next seven days as a series of upper waves traverse the CONUS with favorable wavelengths for air mass/moisture recovery into central portions of the CONUS. Although both the GFS and ECMWF (and their respective ensemble families) show similar synoptic evolutions through the extended period, predictability in any severe threat currently appears greatest on D4/Thursday and D5/Friday. ...D4/Thursday... The upper-level trough currently over the Pacific Northwest is forecast to eject into the upper MS River Valley through the day Thursday with an attendant surface low deepening across the upper MS Valley. A Pacific front is forecast to push east into an expanding warm sector that should span from the MS River into the upper Great Lakes and OH River Valley. Strong mid-level flow orthogonal to the front should generally promote discrete/semi-discrete convection by late afternoon on the eastern fringe of a stout EML. The consistent signal for QPF within the warm sector coincident with 50-60 knot mid-level flow and the intensifying nature of the synoptic low suggests that a widespread severe weather event is possible and may expand further east than depicted in previous forecasts. Despite these trends, regional discrepancies among guidance limit confidence in where the more robust severe corridors will become established. Notable factors limiting confidence are the potential for strong capping across much of the OH Valley and a faster progression of the surface low/front in recent GFS/GEFS solutions (which typically exhibit a fast bias at this range). ...D5/Friday... The Pacific front/outflow associated with D4/Thursday's convection is expected to stall across the lower OH Valley/mid-MS Valley before gradually returning north as an effective warm front on Friday. Ensemble guidance shows a reasonably strong signal for dewpoints in the mid/upper 60s (potentially into the low 70s) along and south of this boundary by peak heating. A mid-level impulse propagating over the region should maintain elongated hodographs and provide sufficient lift for thunderstorm development along the boundary. This synoptic regime suggests that one or more organized clusters/linear segments may propagate along the boundary and into parts of the mid-MS Valley, lower OH Valley, and potentially into the TN Valley. Given the thermodynamic and kinematic environment forecast by ensemble guidance, such a cluster/line will likely pose a severe threat. A 15% risk area has been introduced where the QPF signal associated with this regime has been most consistent over recent model runs, but further forecast refinements are expected. Read more

SPC May 12, 2025 Day 4-8 Severe Weather Outlook

3 months 1 week ago
Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0359 AM CDT Mon May 12 2025 Valid 151200Z - 201200Z ...DISCUSSION... An active period of severe weather is anticipated through early next week based on recent trends in long-range guidance. A transition to a progressive upper-level regime is expected over the next seven days as a series of upper waves traverse the CONUS with favorable wavelengths for air mass/moisture recovery into central portions of the CONUS. Although both the GFS and ECMWF (and their respective ensemble families) show similar synoptic evolutions through the extended period, predictability in any severe threat currently appears greatest on D4/Thursday and D5/Friday. ...D4/Thursday... The upper-level trough currently over the Pacific Northwest is forecast to eject into the upper MS River Valley through the day Thursday with an attendant surface low deepening across the upper MS Valley. A Pacific front is forecast to push east into an expanding warm sector that should span from the MS River into the upper Great Lakes and OH River Valley. Strong mid-level flow orthogonal to the front should generally promote discrete/semi-discrete convection by late afternoon on the eastern fringe of a stout EML. The consistent signal for QPF within the warm sector coincident with 50-60 knot mid-level flow and the intensifying nature of the synoptic low suggests that a widespread severe weather event is possible and may expand further east than depicted in previous forecasts. Despite these trends, regional discrepancies among guidance limit confidence in where the more robust severe corridors will become established. Notable factors limiting confidence are the potential for strong capping across much of the OH Valley and a faster progression of the surface low/front in recent GFS/GEFS solutions (which typically exhibit a fast bias at this range). ...D5/Friday... The Pacific front/outflow associated with D4/Thursday's convection is expected to stall across the lower OH Valley/mid-MS Valley before gradually returning north as an effective warm front on Friday. Ensemble guidance shows a reasonably strong signal for dewpoints in the mid/upper 60s (potentially into the low 70s) along and south of this boundary by peak heating. A mid-level impulse propagating over the region should maintain elongated hodographs and provide sufficient lift for thunderstorm development along the boundary. This synoptic regime suggests that one or more organized clusters/linear segments may propagate along the boundary and into parts of the mid-MS Valley, lower OH Valley, and potentially into the TN Valley. Given the thermodynamic and kinematic environment forecast by ensemble guidance, such a cluster/line will likely pose a severe threat. A 15% risk area has been introduced where the QPF signal associated with this regime has been most consistent over recent model runs, but further forecast refinements are expected. Read more

SPC May 12, 2025 Day 4-8 Severe Weather Outlook

3 months 1 week ago
Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0359 AM CDT Mon May 12 2025 Valid 151200Z - 201200Z ...DISCUSSION... An active period of severe weather is anticipated through early next week based on recent trends in long-range guidance. A transition to a progressive upper-level regime is expected over the next seven days as a series of upper waves traverse the CONUS with favorable wavelengths for air mass/moisture recovery into central portions of the CONUS. Although both the GFS and ECMWF (and their respective ensemble families) show similar synoptic evolutions through the extended period, predictability in any severe threat currently appears greatest on D4/Thursday and D5/Friday. ...D4/Thursday... The upper-level trough currently over the Pacific Northwest is forecast to eject into the upper MS River Valley through the day Thursday with an attendant surface low deepening across the upper MS Valley. A Pacific front is forecast to push east into an expanding warm sector that should span from the MS River into the upper Great Lakes and OH River Valley. Strong mid-level flow orthogonal to the front should generally promote discrete/semi-discrete convection by late afternoon on the eastern fringe of a stout EML. The consistent signal for QPF within the warm sector coincident with 50-60 knot mid-level flow and the intensifying nature of the synoptic low suggests that a widespread severe weather event is possible and may expand further east than depicted in previous forecasts. Despite these trends, regional discrepancies among guidance limit confidence in where the more robust severe corridors will become established. Notable factors limiting confidence are the potential for strong capping across much of the OH Valley and a faster progression of the surface low/front in recent GFS/GEFS solutions (which typically exhibit a fast bias at this range). ...D5/Friday... The Pacific front/outflow associated with D4/Thursday's convection is expected to stall across the lower OH Valley/mid-MS Valley before gradually returning north as an effective warm front on Friday. Ensemble guidance shows a reasonably strong signal for dewpoints in the mid/upper 60s (potentially into the low 70s) along and south of this boundary by peak heating. A mid-level impulse propagating over the region should maintain elongated hodographs and provide sufficient lift for thunderstorm development along the boundary. This synoptic regime suggests that one or more organized clusters/linear segments may propagate along the boundary and into parts of the mid-MS Valley, lower OH Valley, and potentially into the TN Valley. Given the thermodynamic and kinematic environment forecast by ensemble guidance, such a cluster/line will likely pose a severe threat. A 15% risk area has been introduced where the QPF signal associated with this regime has been most consistent over recent model runs, but further forecast refinements are expected. Read more

SPC May 12, 2025 Day 4-8 Severe Weather Outlook

3 months 1 week ago
Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0359 AM CDT Mon May 12 2025 Valid 151200Z - 201200Z ...DISCUSSION... An active period of severe weather is anticipated through early next week based on recent trends in long-range guidance. A transition to a progressive upper-level regime is expected over the next seven days as a series of upper waves traverse the CONUS with favorable wavelengths for air mass/moisture recovery into central portions of the CONUS. Although both the GFS and ECMWF (and their respective ensemble families) show similar synoptic evolutions through the extended period, predictability in any severe threat currently appears greatest on D4/Thursday and D5/Friday. ...D4/Thursday... The upper-level trough currently over the Pacific Northwest is forecast to eject into the upper MS River Valley through the day Thursday with an attendant surface low deepening across the upper MS Valley. A Pacific front is forecast to push east into an expanding warm sector that should span from the MS River into the upper Great Lakes and OH River Valley. Strong mid-level flow orthogonal to the front should generally promote discrete/semi-discrete convection by late afternoon on the eastern fringe of a stout EML. The consistent signal for QPF within the warm sector coincident with 50-60 knot mid-level flow and the intensifying nature of the synoptic low suggests that a widespread severe weather event is possible and may expand further east than depicted in previous forecasts. Despite these trends, regional discrepancies among guidance limit confidence in where the more robust severe corridors will become established. Notable factors limiting confidence are the potential for strong capping across much of the OH Valley and a faster progression of the surface low/front in recent GFS/GEFS solutions (which typically exhibit a fast bias at this range). ...D5/Friday... The Pacific front/outflow associated with D4/Thursday's convection is expected to stall across the lower OH Valley/mid-MS Valley before gradually returning north as an effective warm front on Friday. Ensemble guidance shows a reasonably strong signal for dewpoints in the mid/upper 60s (potentially into the low 70s) along and south of this boundary by peak heating. A mid-level impulse propagating over the region should maintain elongated hodographs and provide sufficient lift for thunderstorm development along the boundary. This synoptic regime suggests that one or more organized clusters/linear segments may propagate along the boundary and into parts of the mid-MS Valley, lower OH Valley, and potentially into the TN Valley. Given the thermodynamic and kinematic environment forecast by ensemble guidance, such a cluster/line will likely pose a severe threat. A 15% risk area has been introduced where the QPF signal associated with this regime has been most consistent over recent model runs, but further forecast refinements are expected. Read more

SPC May 12, 2025 0730 UTC Day 3 Severe Thunderstorm Outlook

3 months 1 week ago
SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0221 AM CDT Mon May 12 2025 Valid 141200Z - 151200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS PARTS OF THE CENTRAL AND NORTHERN PLAINS... ...SUMMARY... Isolated severe thunderstorms are possible across parts of the central to northern Plains Wednesday afternoon and evening. ...Synopsis... A progressive upper trough is forecast to pivot from the Intermountain West into the northern Plains through the day Wednesday. Ahead of this wave, an elongated surface trough draped across the Plains will undergo consolidation as a surface cyclone begins to organize over the Dakotas through the forecast period. The arrival of a cold front coincident with the ejection of the upper trough will provide an impetus for thunderstorm development across the central to northern Plains during the afternoon and evening hours. Further east, a weakening upper wave over the Mid-Atlantic will continue to slowly lift to the northeast. A combination of cold temperatures aloft, moist low-level conditions, and modest broad-scale ascent will promote widespread showers and weak thunderstorms across the upper OH River Valley and Mid-Atlantic region. ...Central/Northern Plains... A somewhat expansive warm sector will become established across much of the Plains through the day Wednesday; however, the eastward advection of a strong EML will hinder convective development for much of the southern and central Plains. Although moisture return into the northern Plains will be somewhat modest compared to locations further south (dewpoints only reaching the mid to upper 50s), strong deep-layer ascent ahead of the approaching wave and within the left-exit region of the attendant mid-level jet will sufficiently erode residual capping by late afternoon to promote thunderstorm initiation along the cold front within an unstable air mass. The favorable thermodynamic and kinematic environment should promote a few strong/severe storms capable of severe hail/wind, though deep-layer shear vectors and initial storm motions largely parallel to the front will promote quick upscale growth into one or more convective clusters/line segments that may limit the overall duration and coverage of the severe threat. A more prolonged, but isolated, severe threat may materialize late evening into the overnight hours within the MO River Valley as isentropic ascent at the terminus of the nocturnal jet increases and promotes additional thunderstorm development - though model consensus regarding this potential is limited at this range. ..Moore.. 05/12/2025 Read more

SPC May 12, 2025 0730 UTC Day 3 Severe Thunderstorm Outlook

3 months 1 week ago
SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0221 AM CDT Mon May 12 2025 Valid 141200Z - 151200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS PARTS OF THE CENTRAL AND NORTHERN PLAINS... ...SUMMARY... Isolated severe thunderstorms are possible across parts of the central to northern Plains Wednesday afternoon and evening. ...Synopsis... A progressive upper trough is forecast to pivot from the Intermountain West into the northern Plains through the day Wednesday. Ahead of this wave, an elongated surface trough draped across the Plains will undergo consolidation as a surface cyclone begins to organize over the Dakotas through the forecast period. The arrival of a cold front coincident with the ejection of the upper trough will provide an impetus for thunderstorm development across the central to northern Plains during the afternoon and evening hours. Further east, a weakening upper wave over the Mid-Atlantic will continue to slowly lift to the northeast. A combination of cold temperatures aloft, moist low-level conditions, and modest broad-scale ascent will promote widespread showers and weak thunderstorms across the upper OH River Valley and Mid-Atlantic region. ...Central/Northern Plains... A somewhat expansive warm sector will become established across much of the Plains through the day Wednesday; however, the eastward advection of a strong EML will hinder convective development for much of the southern and central Plains. Although moisture return into the northern Plains will be somewhat modest compared to locations further south (dewpoints only reaching the mid to upper 50s), strong deep-layer ascent ahead of the approaching wave and within the left-exit region of the attendant mid-level jet will sufficiently erode residual capping by late afternoon to promote thunderstorm initiation along the cold front within an unstable air mass. The favorable thermodynamic and kinematic environment should promote a few strong/severe storms capable of severe hail/wind, though deep-layer shear vectors and initial storm motions largely parallel to the front will promote quick upscale growth into one or more convective clusters/line segments that may limit the overall duration and coverage of the severe threat. A more prolonged, but isolated, severe threat may materialize late evening into the overnight hours within the MO River Valley as isentropic ascent at the terminus of the nocturnal jet increases and promotes additional thunderstorm development - though model consensus regarding this potential is limited at this range. ..Moore.. 05/12/2025 Read more

SPC May 12, 2025 0730 UTC Day 3 Severe Thunderstorm Outlook

3 months 1 week ago
SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0221 AM CDT Mon May 12 2025 Valid 141200Z - 151200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS PARTS OF THE CENTRAL AND NORTHERN PLAINS... ...SUMMARY... Isolated severe thunderstorms are possible across parts of the central to northern Plains Wednesday afternoon and evening. ...Synopsis... A progressive upper trough is forecast to pivot from the Intermountain West into the northern Plains through the day Wednesday. Ahead of this wave, an elongated surface trough draped across the Plains will undergo consolidation as a surface cyclone begins to organize over the Dakotas through the forecast period. The arrival of a cold front coincident with the ejection of the upper trough will provide an impetus for thunderstorm development across the central to northern Plains during the afternoon and evening hours. Further east, a weakening upper wave over the Mid-Atlantic will continue to slowly lift to the northeast. A combination of cold temperatures aloft, moist low-level conditions, and modest broad-scale ascent will promote widespread showers and weak thunderstorms across the upper OH River Valley and Mid-Atlantic region. ...Central/Northern Plains... A somewhat expansive warm sector will become established across much of the Plains through the day Wednesday; however, the eastward advection of a strong EML will hinder convective development for much of the southern and central Plains. Although moisture return into the northern Plains will be somewhat modest compared to locations further south (dewpoints only reaching the mid to upper 50s), strong deep-layer ascent ahead of the approaching wave and within the left-exit region of the attendant mid-level jet will sufficiently erode residual capping by late afternoon to promote thunderstorm initiation along the cold front within an unstable air mass. The favorable thermodynamic and kinematic environment should promote a few strong/severe storms capable of severe hail/wind, though deep-layer shear vectors and initial storm motions largely parallel to the front will promote quick upscale growth into one or more convective clusters/line segments that may limit the overall duration and coverage of the severe threat. A more prolonged, but isolated, severe threat may materialize late evening into the overnight hours within the MO River Valley as isentropic ascent at the terminus of the nocturnal jet increases and promotes additional thunderstorm development - though model consensus regarding this potential is limited at this range. ..Moore.. 05/12/2025 Read more

SPC May 12, 2025 0730 UTC Day 3 Severe Thunderstorm Outlook

3 months 1 week ago
SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0221 AM CDT Mon May 12 2025 Valid 141200Z - 151200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS PARTS OF THE CENTRAL AND NORTHERN PLAINS... ...SUMMARY... Isolated severe thunderstorms are possible across parts of the central to northern Plains Wednesday afternoon and evening. ...Synopsis... A progressive upper trough is forecast to pivot from the Intermountain West into the northern Plains through the day Wednesday. Ahead of this wave, an elongated surface trough draped across the Plains will undergo consolidation as a surface cyclone begins to organize over the Dakotas through the forecast period. The arrival of a cold front coincident with the ejection of the upper trough will provide an impetus for thunderstorm development across the central to northern Plains during the afternoon and evening hours. Further east, a weakening upper wave over the Mid-Atlantic will continue to slowly lift to the northeast. A combination of cold temperatures aloft, moist low-level conditions, and modest broad-scale ascent will promote widespread showers and weak thunderstorms across the upper OH River Valley and Mid-Atlantic region. ...Central/Northern Plains... A somewhat expansive warm sector will become established across much of the Plains through the day Wednesday; however, the eastward advection of a strong EML will hinder convective development for much of the southern and central Plains. Although moisture return into the northern Plains will be somewhat modest compared to locations further south (dewpoints only reaching the mid to upper 50s), strong deep-layer ascent ahead of the approaching wave and within the left-exit region of the attendant mid-level jet will sufficiently erode residual capping by late afternoon to promote thunderstorm initiation along the cold front within an unstable air mass. The favorable thermodynamic and kinematic environment should promote a few strong/severe storms capable of severe hail/wind, though deep-layer shear vectors and initial storm motions largely parallel to the front will promote quick upscale growth into one or more convective clusters/line segments that may limit the overall duration and coverage of the severe threat. A more prolonged, but isolated, severe threat may materialize late evening into the overnight hours within the MO River Valley as isentropic ascent at the terminus of the nocturnal jet increases and promotes additional thunderstorm development - though model consensus regarding this potential is limited at this range. ..Moore.. 05/12/2025 Read more