Severe Storms

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0206 PM CDT Wed Sep 18 2024 Valid 201200Z - 211200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected on Friday. ...Synopsis... Separate northern-stream and southern-stream mid/upper-level shortwave troughs are forecast to move across parts of the West on Friday, with the northern shortwave reaching the northern Great Plains and Canadian Prairies by Saturday morning. Meanwhile, a stout midlevel anticyclone (with the warmest 500 mb temperatures near or slightly above 0C) will remain anchored over Texas. A weakening mid/upper-level shortwave trough is forecast to move across parts of the Great Lakes and Ohio Valley. At the surface, a weakening cold front will extend somewhere from the south-central Great Plains into parts of the Midwest/Great Lakes by late afternoon. This front may tend to stall with time, and potentially move northward as warm front across the central Plains later Friday night into Saturday morning. A general lack of overlap between favorable moisture/instability and stronger ascent/deep-layer flow is currently expected to limit organized severe potential on Friday. Isolated diurnal storm development will be possible near the weakening front from the Plains into parts of the Great Lakes/Ohio Valley. Elevated storm development will also be possible Friday night into Saturday morning across parts of the central Plains, within a warm-advection regime. It remains uncertain if elevated buoyancy will become sufficient for any hail potential with the stronger storms within this regime. High-based convection that may be capable of localized strong gusts will be possible across parts of the Southwest and southern Rockies, in association with the southern-stream shortwave trough. ..Dean.. 09/18/2024 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0206 PM CDT Wed Sep 18 2024 Valid 201200Z - 211200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected on Friday. ...Synopsis... Separate northern-stream and southern-stream mid/upper-level shortwave troughs are forecast to move across parts of the West on Friday, with the northern shortwave reaching the northern Great Plains and Canadian Prairies by Saturday morning. Meanwhile, a stout midlevel anticyclone (with the warmest 500 mb temperatures near or slightly above 0C) will remain anchored over Texas. A weakening mid/upper-level shortwave trough is forecast to move across parts of the Great Lakes and Ohio Valley. At the surface, a weakening cold front will extend somewhere from the south-central Great Plains into parts of the Midwest/Great Lakes by late afternoon. This front may tend to stall with time, and potentially move northward as warm front across the central Plains later Friday night into Saturday morning. A general lack of overlap between favorable moisture/instability and stronger ascent/deep-layer flow is currently expected to limit organized severe potential on Friday. Isolated diurnal storm development will be possible near the weakening front from the Plains into parts of the Great Lakes/Ohio Valley. Elevated storm development will also be possible Friday night into Saturday morning across parts of the central Plains, within a warm-advection regime. It remains uncertain if elevated buoyancy will become sufficient for any hail potential with the stronger storms within this regime. High-based convection that may be capable of localized strong gusts will be possible across parts of the Southwest and southern Rockies, in association with the southern-stream shortwave trough. ..Dean.. 09/18/2024 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0206 PM CDT Wed Sep 18 2024 Valid 201200Z - 211200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected on Friday. ...Synopsis... Separate northern-stream and southern-stream mid/upper-level shortwave troughs are forecast to move across parts of the West on Friday, with the northern shortwave reaching the northern Great Plains and Canadian Prairies by Saturday morning. Meanwhile, a stout midlevel anticyclone (with the warmest 500 mb temperatures near or slightly above 0C) will remain anchored over Texas. A weakening mid/upper-level shortwave trough is forecast to move across parts of the Great Lakes and Ohio Valley. At the surface, a weakening cold front will extend somewhere from the south-central Great Plains into parts of the Midwest/Great Lakes by late afternoon. This front may tend to stall with time, and potentially move northward as warm front across the central Plains later Friday night into Saturday morning. A general lack of overlap between favorable moisture/instability and stronger ascent/deep-layer flow is currently expected to limit organized severe potential on Friday. Isolated diurnal storm development will be possible near the weakening front from the Plains into parts of the Great Lakes/Ohio Valley. Elevated storm development will also be possible Friday night into Saturday morning across parts of the central Plains, within a warm-advection regime. It remains uncertain if elevated buoyancy will become sufficient for any hail potential with the stronger storms within this regime. High-based convection that may be capable of localized strong gusts will be possible across parts of the Southwest and southern Rockies, in association with the southern-stream shortwave trough. ..Dean.. 09/18/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Wed Sep 18 2024 Valid 191200Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE UPPER MIDWEST... ...SUMMARY... Scattered severe thunderstorms are possible from mid-afternoon to mid-evening on Thursday across central/eastern Minnesota, Iowa, and western Wisconsin. A few tornadoes, isolated very large hail, and damaging winds may occur. ...Upper Midwest... A seasonably strong stacked cyclone initially near the ND/SK/MB border region is forecast to move northeastward through the period. An attendant cold front will move eastward through the day across parts of the upper Midwest and central Plains. Diurnal heating of a rather moist airmass along/east of the front will support a relatively narrow zone of moderate to large MLCAPE (1500-3000 J/kg) by peak heating. Moderate midlevel flow will support sufficient effective shear for storm organization, with shear vectors generally aligned perpendicular to the front. This will support supercell potential from central/eastern MN into western WI and parts of IA, though the timing of initial development and western extent of the primary severe threat remain somewhat uncertain. Favorable instability and an initially discrete storm mode will support large to very large hail as storms mature, along with some potential for isolated damaging wind. Low-level hodographs will also be sufficiently curved/enlarged to support a tornado threat. A tendency toward clustering and perhaps some modest upscale growth is possible later in the storm evolution, with a severe threat likely persisting into the early/mid evening. The threat should begin to wane by late evening into Thursday night, as instability weakens with time and eastward extent. ...Eastern KS/northern OK into southeast NE/western MO... A conditionally favorable storm environment is also expected to develop from southeast NE into eastern KS/western MO and northern OK, along/ahead of the approaching front. While storm coverage will generally be less compared to areas farther north (due to weaker large-scale ascent), isolated supercells and/or stronger clusters will be possible from late afternoon into the evening. Increasingly warm midlevel temperatures will tend to limit updraft intensity with southward extent, but an isolated severe threat could extend as far south as northern OK. ..Dean.. 09/18/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Wed Sep 18 2024 Valid 191200Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE UPPER MIDWEST... ...SUMMARY... Scattered severe thunderstorms are possible from mid-afternoon to mid-evening on Thursday across central/eastern Minnesota, Iowa, and western Wisconsin. A few tornadoes, isolated very large hail, and damaging winds may occur. ...Upper Midwest... A seasonably strong stacked cyclone initially near the ND/SK/MB border region is forecast to move northeastward through the period. An attendant cold front will move eastward through the day across parts of the upper Midwest and central Plains. Diurnal heating of a rather moist airmass along/east of the front will support a relatively narrow zone of moderate to large MLCAPE (1500-3000 J/kg) by peak heating. Moderate midlevel flow will support sufficient effective shear for storm organization, with shear vectors generally aligned perpendicular to the front. This will support supercell potential from central/eastern MN into western WI and parts of IA, though the timing of initial development and western extent of the primary severe threat remain somewhat uncertain. Favorable instability and an initially discrete storm mode will support large to very large hail as storms mature, along with some potential for isolated damaging wind. Low-level hodographs will also be sufficiently curved/enlarged to support a tornado threat. A tendency toward clustering and perhaps some modest upscale growth is possible later in the storm evolution, with a severe threat likely persisting into the early/mid evening. The threat should begin to wane by late evening into Thursday night, as instability weakens with time and eastward extent. ...Eastern KS/northern OK into southeast NE/western MO... A conditionally favorable storm environment is also expected to develop from southeast NE into eastern KS/western MO and northern OK, along/ahead of the approaching front. While storm coverage will generally be less compared to areas farther north (due to weaker large-scale ascent), isolated supercells and/or stronger clusters will be possible from late afternoon into the evening. Increasingly warm midlevel temperatures will tend to limit updraft intensity with southward extent, but an isolated severe threat could extend as far south as northern OK. ..Dean.. 09/18/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Wed Sep 18 2024 Valid 191200Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE UPPER MIDWEST... ...SUMMARY... Scattered severe thunderstorms are possible from mid-afternoon to mid-evening on Thursday across central/eastern Minnesota, Iowa, and western Wisconsin. A few tornadoes, isolated very large hail, and damaging winds may occur. ...Upper Midwest... A seasonably strong stacked cyclone initially near the ND/SK/MB border region is forecast to move northeastward through the period. An attendant cold front will move eastward through the day across parts of the upper Midwest and central Plains. Diurnal heating of a rather moist airmass along/east of the front will support a relatively narrow zone of moderate to large MLCAPE (1500-3000 J/kg) by peak heating. Moderate midlevel flow will support sufficient effective shear for storm organization, with shear vectors generally aligned perpendicular to the front. This will support supercell potential from central/eastern MN into western WI and parts of IA, though the timing of initial development and western extent of the primary severe threat remain somewhat uncertain. Favorable instability and an initially discrete storm mode will support large to very large hail as storms mature, along with some potential for isolated damaging wind. Low-level hodographs will also be sufficiently curved/enlarged to support a tornado threat. A tendency toward clustering and perhaps some modest upscale growth is possible later in the storm evolution, with a severe threat likely persisting into the early/mid evening. The threat should begin to wane by late evening into Thursday night, as instability weakens with time and eastward extent. ...Eastern KS/northern OK into southeast NE/western MO... A conditionally favorable storm environment is also expected to develop from southeast NE into eastern KS/western MO and northern OK, along/ahead of the approaching front. While storm coverage will generally be less compared to areas farther north (due to weaker large-scale ascent), isolated supercells and/or stronger clusters will be possible from late afternoon into the evening. Increasingly warm midlevel temperatures will tend to limit updraft intensity with southward extent, but an isolated severe threat could extend as far south as northern OK. ..Dean.. 09/18/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Wed Sep 18 2024 Valid 191200Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE UPPER MIDWEST... ...SUMMARY... Scattered severe thunderstorms are possible from mid-afternoon to mid-evening on Thursday across central/eastern Minnesota, Iowa, and western Wisconsin. A few tornadoes, isolated very large hail, and damaging winds may occur. ...Upper Midwest... A seasonably strong stacked cyclone initially near the ND/SK/MB border region is forecast to move northeastward through the period. An attendant cold front will move eastward through the day across parts of the upper Midwest and central Plains. Diurnal heating of a rather moist airmass along/east of the front will support a relatively narrow zone of moderate to large MLCAPE (1500-3000 J/kg) by peak heating. Moderate midlevel flow will support sufficient effective shear for storm organization, with shear vectors generally aligned perpendicular to the front. This will support supercell potential from central/eastern MN into western WI and parts of IA, though the timing of initial development and western extent of the primary severe threat remain somewhat uncertain. Favorable instability and an initially discrete storm mode will support large to very large hail as storms mature, along with some potential for isolated damaging wind. Low-level hodographs will also be sufficiently curved/enlarged to support a tornado threat. A tendency toward clustering and perhaps some modest upscale growth is possible later in the storm evolution, with a severe threat likely persisting into the early/mid evening. The threat should begin to wane by late evening into Thursday night, as instability weakens with time and eastward extent. ...Eastern KS/northern OK into southeast NE/western MO... A conditionally favorable storm environment is also expected to develop from southeast NE into eastern KS/western MO and northern OK, along/ahead of the approaching front. While storm coverage will generally be less compared to areas farther north (due to weaker large-scale ascent), isolated supercells and/or stronger clusters will be possible from late afternoon into the evening. Increasingly warm midlevel temperatures will tend to limit updraft intensity with southward extent, but an isolated severe threat could extend as far south as northern OK. ..Dean.. 09/18/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Wed Sep 18 2024 Valid 191200Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE UPPER MIDWEST... ...SUMMARY... Scattered severe thunderstorms are possible from mid-afternoon to mid-evening on Thursday across central/eastern Minnesota, Iowa, and western Wisconsin. A few tornadoes, isolated very large hail, and damaging winds may occur. ...Upper Midwest... A seasonably strong stacked cyclone initially near the ND/SK/MB border region is forecast to move northeastward through the period. An attendant cold front will move eastward through the day across parts of the upper Midwest and central Plains. Diurnal heating of a rather moist airmass along/east of the front will support a relatively narrow zone of moderate to large MLCAPE (1500-3000 J/kg) by peak heating. Moderate midlevel flow will support sufficient effective shear for storm organization, with shear vectors generally aligned perpendicular to the front. This will support supercell potential from central/eastern MN into western WI and parts of IA, though the timing of initial development and western extent of the primary severe threat remain somewhat uncertain. Favorable instability and an initially discrete storm mode will support large to very large hail as storms mature, along with some potential for isolated damaging wind. Low-level hodographs will also be sufficiently curved/enlarged to support a tornado threat. A tendency toward clustering and perhaps some modest upscale growth is possible later in the storm evolution, with a severe threat likely persisting into the early/mid evening. The threat should begin to wane by late evening into Thursday night, as instability weakens with time and eastward extent. ...Eastern KS/northern OK into southeast NE/western MO... A conditionally favorable storm environment is also expected to develop from southeast NE into eastern KS/western MO and northern OK, along/ahead of the approaching front. While storm coverage will generally be less compared to areas farther north (due to weaker large-scale ascent), isolated supercells and/or stronger clusters will be possible from late afternoon into the evening. Increasingly warm midlevel temperatures will tend to limit updraft intensity with southward extent, but an isolated severe threat could extend as far south as northern OK. ..Dean.. 09/18/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Wed Sep 18 2024 Valid 191200Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE UPPER MIDWEST... ...SUMMARY... Scattered severe thunderstorms are possible from mid-afternoon to mid-evening on Thursday across central/eastern Minnesota, Iowa, and western Wisconsin. A few tornadoes, isolated very large hail, and damaging winds may occur. ...Upper Midwest... A seasonably strong stacked cyclone initially near the ND/SK/MB border region is forecast to move northeastward through the period. An attendant cold front will move eastward through the day across parts of the upper Midwest and central Plains. Diurnal heating of a rather moist airmass along/east of the front will support a relatively narrow zone of moderate to large MLCAPE (1500-3000 J/kg) by peak heating. Moderate midlevel flow will support sufficient effective shear for storm organization, with shear vectors generally aligned perpendicular to the front. This will support supercell potential from central/eastern MN into western WI and parts of IA, though the timing of initial development and western extent of the primary severe threat remain somewhat uncertain. Favorable instability and an initially discrete storm mode will support large to very large hail as storms mature, along with some potential for isolated damaging wind. Low-level hodographs will also be sufficiently curved/enlarged to support a tornado threat. A tendency toward clustering and perhaps some modest upscale growth is possible later in the storm evolution, with a severe threat likely persisting into the early/mid evening. The threat should begin to wane by late evening into Thursday night, as instability weakens with time and eastward extent. ...Eastern KS/northern OK into southeast NE/western MO... A conditionally favorable storm environment is also expected to develop from southeast NE into eastern KS/western MO and northern OK, along/ahead of the approaching front. While storm coverage will generally be less compared to areas farther north (due to weaker large-scale ascent), isolated supercells and/or stronger clusters will be possible from late afternoon into the evening. Increasingly warm midlevel temperatures will tend to limit updraft intensity with southward extent, but an isolated severe threat could extend as far south as northern OK. ..Dean.. 09/18/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Wed Sep 18 2024 Valid 191200Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE UPPER MIDWEST... ...SUMMARY... Scattered severe thunderstorms are possible from mid-afternoon to mid-evening on Thursday across central/eastern Minnesota, Iowa, and western Wisconsin. A few tornadoes, isolated very large hail, and damaging winds may occur. ...Upper Midwest... A seasonably strong stacked cyclone initially near the ND/SK/MB border region is forecast to move northeastward through the period. An attendant cold front will move eastward through the day across parts of the upper Midwest and central Plains. Diurnal heating of a rather moist airmass along/east of the front will support a relatively narrow zone of moderate to large MLCAPE (1500-3000 J/kg) by peak heating. Moderate midlevel flow will support sufficient effective shear for storm organization, with shear vectors generally aligned perpendicular to the front. This will support supercell potential from central/eastern MN into western WI and parts of IA, though the timing of initial development and western extent of the primary severe threat remain somewhat uncertain. Favorable instability and an initially discrete storm mode will support large to very large hail as storms mature, along with some potential for isolated damaging wind. Low-level hodographs will also be sufficiently curved/enlarged to support a tornado threat. A tendency toward clustering and perhaps some modest upscale growth is possible later in the storm evolution, with a severe threat likely persisting into the early/mid evening. The threat should begin to wane by late evening into Thursday night, as instability weakens with time and eastward extent. ...Eastern KS/northern OK into southeast NE/western MO... A conditionally favorable storm environment is also expected to develop from southeast NE into eastern KS/western MO and northern OK, along/ahead of the approaching front. While storm coverage will generally be less compared to areas farther north (due to weaker large-scale ascent), isolated supercells and/or stronger clusters will be possible from late afternoon into the evening. Increasingly warm midlevel temperatures will tend to limit updraft intensity with southward extent, but an isolated severe threat could extend as far south as northern OK. ..Dean.. 09/18/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Wed Sep 18 2024 Valid 191200Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE UPPER MIDWEST... ...SUMMARY... Scattered severe thunderstorms are possible from mid-afternoon to mid-evening on Thursday across central/eastern Minnesota, Iowa, and western Wisconsin. A few tornadoes, isolated very large hail, and damaging winds may occur. ...Upper Midwest... A seasonably strong stacked cyclone initially near the ND/SK/MB border region is forecast to move northeastward through the period. An attendant cold front will move eastward through the day across parts of the upper Midwest and central Plains. Diurnal heating of a rather moist airmass along/east of the front will support a relatively narrow zone of moderate to large MLCAPE (1500-3000 J/kg) by peak heating. Moderate midlevel flow will support sufficient effective shear for storm organization, with shear vectors generally aligned perpendicular to the front. This will support supercell potential from central/eastern MN into western WI and parts of IA, though the timing of initial development and western extent of the primary severe threat remain somewhat uncertain. Favorable instability and an initially discrete storm mode will support large to very large hail as storms mature, along with some potential for isolated damaging wind. Low-level hodographs will also be sufficiently curved/enlarged to support a tornado threat. A tendency toward clustering and perhaps some modest upscale growth is possible later in the storm evolution, with a severe threat likely persisting into the early/mid evening. The threat should begin to wane by late evening into Thursday night, as instability weakens with time and eastward extent. ...Eastern KS/northern OK into southeast NE/western MO... A conditionally favorable storm environment is also expected to develop from southeast NE into eastern KS/western MO and northern OK, along/ahead of the approaching front. While storm coverage will generally be less compared to areas farther north (due to weaker large-scale ascent), isolated supercells and/or stronger clusters will be possible from late afternoon into the evening. Increasingly warm midlevel temperatures will tend to limit updraft intensity with southward extent, but an isolated severe threat could extend as far south as northern OK. ..Dean.. 09/18/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1118 AM CDT Wed Sep 18 2024 Valid 181630Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTHEAST NEBRASKA INTO FAR NORTHWEST IOWA...EASTERN SOUTH DAKOTA...AND WESTERN MINNESOTA... ...SUMMARY... Thunderstorms capable of producing severe wind gusts and large hail are possible today across parts of the eastern Dakotas and Minnesota into the mid Missouri Valley. A marginal severe threat will also extend southward into parts of the central and southern Plains. ...Northern Plains/Upper Midwest to the Southern High Plains... A closed upper low centered over eastern MT will continue northeastward during the period, reaching southeast SK by early Thursday morning. Upper-level ridging extending northward from the northwest Gulf Coast into the upper MS Valley will slowly shift eastward to the Upper Great Lakes. A belt of enhanced southwesterly mid-level flow will extend from southern CA through the central High Plains, while also wrapping cyclonically through the eastern Dakotas and into southern Canada. At the surface, a trough/front extends southward from central ND into SD and western NE, before continuing southwestward over the central/southern High Plains. This boundary may serve as a focus for renewed thunderstorm development later today. A band of elevated convection has generally moved northward from northeast ND and northwest MN into southern MB. In the wake of this activity, cloud cover remains prevalent across much of the warm sector across the northern Plains/Upper Midwest. Still, filtered daytime heating of an adequately moist boundary layer should aid in the development of around 1500-2000 J/kg of MLCAPE by late afternoon. Isolated to scattered thunderstorms may form along/east of the surface trough/front within a favorable zone of 30-40 kt of effective bulk shear. But, better large-scale forcing associated with the upper low over the northern High Plains will tend to remain displaced north and west (in southern Canada). Accordingly, 12Z high-resolution guidance continues to vary regarding storm coverage across the Slight Risk (isolated versus scattered) given the weaker forcing aloft. Even with this continued uncertainty, various NAM/RAP forecast soundings still suggest a somewhat conditional risk for organized storms (mix of multicells and supercells). Severe hail/wind may accompany the stronger storms from late afternoon through early evening, before this activity eventually weakens. Further south into the central/southern Plains, low-levels are forecast to be somewhat drier near the surface trough, with surface dewpoints expected to mostly range in the upper 50s to low 60s by late afternoon with pronounced boundary-layer mixing. Warmer mid-level temperatures and limited large-scale ascent across these regions should temper the overall intensity of any updrafts that can form and be sustained, and resultant intensity/coverage of this convection. Still, some guidance shows locally greater thunderstorm coverage and resulting isolated severe wind threat from the eastern TX Panhandle into far northwest OK and southern KS during the late afternoon/early evening, where low-level lapse rates should be maximized with robust daytime heating. ..Gleason/Moore.. 09/18/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1118 AM CDT Wed Sep 18 2024 Valid 181630Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTHEAST NEBRASKA INTO FAR NORTHWEST IOWA...EASTERN SOUTH DAKOTA...AND WESTERN MINNESOTA... ...SUMMARY... Thunderstorms capable of producing severe wind gusts and large hail are possible today across parts of the eastern Dakotas and Minnesota into the mid Missouri Valley. A marginal severe threat will also extend southward into parts of the central and southern Plains. ...Northern Plains/Upper Midwest to the Southern High Plains... A closed upper low centered over eastern MT will continue northeastward during the period, reaching southeast SK by early Thursday morning. Upper-level ridging extending northward from the northwest Gulf Coast into the upper MS Valley will slowly shift eastward to the Upper Great Lakes. A belt of enhanced southwesterly mid-level flow will extend from southern CA through the central High Plains, while also wrapping cyclonically through the eastern Dakotas and into southern Canada. At the surface, a trough/front extends southward from central ND into SD and western NE, before continuing southwestward over the central/southern High Plains. This boundary may serve as a focus for renewed thunderstorm development later today. A band of elevated convection has generally moved northward from northeast ND and northwest MN into southern MB. In the wake of this activity, cloud cover remains prevalent across much of the warm sector across the northern Plains/Upper Midwest. Still, filtered daytime heating of an adequately moist boundary layer should aid in the development of around 1500-2000 J/kg of MLCAPE by late afternoon. Isolated to scattered thunderstorms may form along/east of the surface trough/front within a favorable zone of 30-40 kt of effective bulk shear. But, better large-scale forcing associated with the upper low over the northern High Plains will tend to remain displaced north and west (in southern Canada). Accordingly, 12Z high-resolution guidance continues to vary regarding storm coverage across the Slight Risk (isolated versus scattered) given the weaker forcing aloft. Even with this continued uncertainty, various NAM/RAP forecast soundings still suggest a somewhat conditional risk for organized storms (mix of multicells and supercells). Severe hail/wind may accompany the stronger storms from late afternoon through early evening, before this activity eventually weakens. Further south into the central/southern Plains, low-levels are forecast to be somewhat drier near the surface trough, with surface dewpoints expected to mostly range in the upper 50s to low 60s by late afternoon with pronounced boundary-layer mixing. Warmer mid-level temperatures and limited large-scale ascent across these regions should temper the overall intensity of any updrafts that can form and be sustained, and resultant intensity/coverage of this convection. Still, some guidance shows locally greater thunderstorm coverage and resulting isolated severe wind threat from the eastern TX Panhandle into far northwest OK and southern KS during the late afternoon/early evening, where low-level lapse rates should be maximized with robust daytime heating. ..Gleason/Moore.. 09/18/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1118 AM CDT Wed Sep 18 2024 Valid 181630Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTHEAST NEBRASKA INTO FAR NORTHWEST IOWA...EASTERN SOUTH DAKOTA...AND WESTERN MINNESOTA... ...SUMMARY... Thunderstorms capable of producing severe wind gusts and large hail are possible today across parts of the eastern Dakotas and Minnesota into the mid Missouri Valley. A marginal severe threat will also extend southward into parts of the central and southern Plains. ...Northern Plains/Upper Midwest to the Southern High Plains... A closed upper low centered over eastern MT will continue northeastward during the period, reaching southeast SK by early Thursday morning. Upper-level ridging extending northward from the northwest Gulf Coast into the upper MS Valley will slowly shift eastward to the Upper Great Lakes. A belt of enhanced southwesterly mid-level flow will extend from southern CA through the central High Plains, while also wrapping cyclonically through the eastern Dakotas and into southern Canada. At the surface, a trough/front extends southward from central ND into SD and western NE, before continuing southwestward over the central/southern High Plains. This boundary may serve as a focus for renewed thunderstorm development later today. A band of elevated convection has generally moved northward from northeast ND and northwest MN into southern MB. In the wake of this activity, cloud cover remains prevalent across much of the warm sector across the northern Plains/Upper Midwest. Still, filtered daytime heating of an adequately moist boundary layer should aid in the development of around 1500-2000 J/kg of MLCAPE by late afternoon. Isolated to scattered thunderstorms may form along/east of the surface trough/front within a favorable zone of 30-40 kt of effective bulk shear. But, better large-scale forcing associated with the upper low over the northern High Plains will tend to remain displaced north and west (in southern Canada). Accordingly, 12Z high-resolution guidance continues to vary regarding storm coverage across the Slight Risk (isolated versus scattered) given the weaker forcing aloft. Even with this continued uncertainty, various NAM/RAP forecast soundings still suggest a somewhat conditional risk for organized storms (mix of multicells and supercells). Severe hail/wind may accompany the stronger storms from late afternoon through early evening, before this activity eventually weakens. Further south into the central/southern Plains, low-levels are forecast to be somewhat drier near the surface trough, with surface dewpoints expected to mostly range in the upper 50s to low 60s by late afternoon with pronounced boundary-layer mixing. Warmer mid-level temperatures and limited large-scale ascent across these regions should temper the overall intensity of any updrafts that can form and be sustained, and resultant intensity/coverage of this convection. Still, some guidance shows locally greater thunderstorm coverage and resulting isolated severe wind threat from the eastern TX Panhandle into far northwest OK and southern KS during the late afternoon/early evening, where low-level lapse rates should be maximized with robust daytime heating. ..Gleason/Moore.. 09/18/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1118 AM CDT Wed Sep 18 2024 Valid 181630Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTHEAST NEBRASKA INTO FAR NORTHWEST IOWA...EASTERN SOUTH DAKOTA...AND WESTERN MINNESOTA... ...SUMMARY... Thunderstorms capable of producing severe wind gusts and large hail are possible today across parts of the eastern Dakotas and Minnesota into the mid Missouri Valley. A marginal severe threat will also extend southward into parts of the central and southern Plains. ...Northern Plains/Upper Midwest to the Southern High Plains... A closed upper low centered over eastern MT will continue northeastward during the period, reaching southeast SK by early Thursday morning. Upper-level ridging extending northward from the northwest Gulf Coast into the upper MS Valley will slowly shift eastward to the Upper Great Lakes. A belt of enhanced southwesterly mid-level flow will extend from southern CA through the central High Plains, while also wrapping cyclonically through the eastern Dakotas and into southern Canada. At the surface, a trough/front extends southward from central ND into SD and western NE, before continuing southwestward over the central/southern High Plains. This boundary may serve as a focus for renewed thunderstorm development later today. A band of elevated convection has generally moved northward from northeast ND and northwest MN into southern MB. In the wake of this activity, cloud cover remains prevalent across much of the warm sector across the northern Plains/Upper Midwest. Still, filtered daytime heating of an adequately moist boundary layer should aid in the development of around 1500-2000 J/kg of MLCAPE by late afternoon. Isolated to scattered thunderstorms may form along/east of the surface trough/front within a favorable zone of 30-40 kt of effective bulk shear. But, better large-scale forcing associated with the upper low over the northern High Plains will tend to remain displaced north and west (in southern Canada). Accordingly, 12Z high-resolution guidance continues to vary regarding storm coverage across the Slight Risk (isolated versus scattered) given the weaker forcing aloft. Even with this continued uncertainty, various NAM/RAP forecast soundings still suggest a somewhat conditional risk for organized storms (mix of multicells and supercells). Severe hail/wind may accompany the stronger storms from late afternoon through early evening, before this activity eventually weakens. Further south into the central/southern Plains, low-levels are forecast to be somewhat drier near the surface trough, with surface dewpoints expected to mostly range in the upper 50s to low 60s by late afternoon with pronounced boundary-layer mixing. Warmer mid-level temperatures and limited large-scale ascent across these regions should temper the overall intensity of any updrafts that can form and be sustained, and resultant intensity/coverage of this convection. Still, some guidance shows locally greater thunderstorm coverage and resulting isolated severe wind threat from the eastern TX Panhandle into far northwest OK and southern KS during the late afternoon/early evening, where low-level lapse rates should be maximized with robust daytime heating. ..Gleason/Moore.. 09/18/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1118 AM CDT Wed Sep 18 2024 Valid 181630Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTHEAST NEBRASKA INTO FAR NORTHWEST IOWA...EASTERN SOUTH DAKOTA...AND WESTERN MINNESOTA... ...SUMMARY... Thunderstorms capable of producing severe wind gusts and large hail are possible today across parts of the eastern Dakotas and Minnesota into the mid Missouri Valley. A marginal severe threat will also extend southward into parts of the central and southern Plains. ...Northern Plains/Upper Midwest to the Southern High Plains... A closed upper low centered over eastern MT will continue northeastward during the period, reaching southeast SK by early Thursday morning. Upper-level ridging extending northward from the northwest Gulf Coast into the upper MS Valley will slowly shift eastward to the Upper Great Lakes. A belt of enhanced southwesterly mid-level flow will extend from southern CA through the central High Plains, while also wrapping cyclonically through the eastern Dakotas and into southern Canada. At the surface, a trough/front extends southward from central ND into SD and western NE, before continuing southwestward over the central/southern High Plains. This boundary may serve as a focus for renewed thunderstorm development later today. A band of elevated convection has generally moved northward from northeast ND and northwest MN into southern MB. In the wake of this activity, cloud cover remains prevalent across much of the warm sector across the northern Plains/Upper Midwest. Still, filtered daytime heating of an adequately moist boundary layer should aid in the development of around 1500-2000 J/kg of MLCAPE by late afternoon. Isolated to scattered thunderstorms may form along/east of the surface trough/front within a favorable zone of 30-40 kt of effective bulk shear. But, better large-scale forcing associated with the upper low over the northern High Plains will tend to remain displaced north and west (in southern Canada). Accordingly, 12Z high-resolution guidance continues to vary regarding storm coverage across the Slight Risk (isolated versus scattered) given the weaker forcing aloft. Even with this continued uncertainty, various NAM/RAP forecast soundings still suggest a somewhat conditional risk for organized storms (mix of multicells and supercells). Severe hail/wind may accompany the stronger storms from late afternoon through early evening, before this activity eventually weakens. Further south into the central/southern Plains, low-levels are forecast to be somewhat drier near the surface trough, with surface dewpoints expected to mostly range in the upper 50s to low 60s by late afternoon with pronounced boundary-layer mixing. Warmer mid-level temperatures and limited large-scale ascent across these regions should temper the overall intensity of any updrafts that can form and be sustained, and resultant intensity/coverage of this convection. Still, some guidance shows locally greater thunderstorm coverage and resulting isolated severe wind threat from the eastern TX Panhandle into far northwest OK and southern KS during the late afternoon/early evening, where low-level lapse rates should be maximized with robust daytime heating. ..Gleason/Moore.. 09/18/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1118 AM CDT Wed Sep 18 2024 Valid 181630Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTHEAST NEBRASKA INTO FAR NORTHWEST IOWA...EASTERN SOUTH DAKOTA...AND WESTERN MINNESOTA... ...SUMMARY... Thunderstorms capable of producing severe wind gusts and large hail are possible today across parts of the eastern Dakotas and Minnesota into the mid Missouri Valley. A marginal severe threat will also extend southward into parts of the central and southern Plains. ...Northern Plains/Upper Midwest to the Southern High Plains... A closed upper low centered over eastern MT will continue northeastward during the period, reaching southeast SK by early Thursday morning. Upper-level ridging extending northward from the northwest Gulf Coast into the upper MS Valley will slowly shift eastward to the Upper Great Lakes. A belt of enhanced southwesterly mid-level flow will extend from southern CA through the central High Plains, while also wrapping cyclonically through the eastern Dakotas and into southern Canada. At the surface, a trough/front extends southward from central ND into SD and western NE, before continuing southwestward over the central/southern High Plains. This boundary may serve as a focus for renewed thunderstorm development later today. A band of elevated convection has generally moved northward from northeast ND and northwest MN into southern MB. In the wake of this activity, cloud cover remains prevalent across much of the warm sector across the northern Plains/Upper Midwest. Still, filtered daytime heating of an adequately moist boundary layer should aid in the development of around 1500-2000 J/kg of MLCAPE by late afternoon. Isolated to scattered thunderstorms may form along/east of the surface trough/front within a favorable zone of 30-40 kt of effective bulk shear. But, better large-scale forcing associated with the upper low over the northern High Plains will tend to remain displaced north and west (in southern Canada). Accordingly, 12Z high-resolution guidance continues to vary regarding storm coverage across the Slight Risk (isolated versus scattered) given the weaker forcing aloft. Even with this continued uncertainty, various NAM/RAP forecast soundings still suggest a somewhat conditional risk for organized storms (mix of multicells and supercells). Severe hail/wind may accompany the stronger storms from late afternoon through early evening, before this activity eventually weakens. Further south into the central/southern Plains, low-levels are forecast to be somewhat drier near the surface trough, with surface dewpoints expected to mostly range in the upper 50s to low 60s by late afternoon with pronounced boundary-layer mixing. Warmer mid-level temperatures and limited large-scale ascent across these regions should temper the overall intensity of any updrafts that can form and be sustained, and resultant intensity/coverage of this convection. Still, some guidance shows locally greater thunderstorm coverage and resulting isolated severe wind threat from the eastern TX Panhandle into far northwest OK and southern KS during the late afternoon/early evening, where low-level lapse rates should be maximized with robust daytime heating. ..Gleason/Moore.. 09/18/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1118 AM CDT Wed Sep 18 2024 Valid 181630Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTHEAST NEBRASKA INTO FAR NORTHWEST IOWA...EASTERN SOUTH DAKOTA...AND WESTERN MINNESOTA... ...SUMMARY... Thunderstorms capable of producing severe wind gusts and large hail are possible today across parts of the eastern Dakotas and Minnesota into the mid Missouri Valley. A marginal severe threat will also extend southward into parts of the central and southern Plains. ...Northern Plains/Upper Midwest to the Southern High Plains... A closed upper low centered over eastern MT will continue northeastward during the period, reaching southeast SK by early Thursday morning. Upper-level ridging extending northward from the northwest Gulf Coast into the upper MS Valley will slowly shift eastward to the Upper Great Lakes. A belt of enhanced southwesterly mid-level flow will extend from southern CA through the central High Plains, while also wrapping cyclonically through the eastern Dakotas and into southern Canada. At the surface, a trough/front extends southward from central ND into SD and western NE, before continuing southwestward over the central/southern High Plains. This boundary may serve as a focus for renewed thunderstorm development later today. A band of elevated convection has generally moved northward from northeast ND and northwest MN into southern MB. In the wake of this activity, cloud cover remains prevalent across much of the warm sector across the northern Plains/Upper Midwest. Still, filtered daytime heating of an adequately moist boundary layer should aid in the development of around 1500-2000 J/kg of MLCAPE by late afternoon. Isolated to scattered thunderstorms may form along/east of the surface trough/front within a favorable zone of 30-40 kt of effective bulk shear. But, better large-scale forcing associated with the upper low over the northern High Plains will tend to remain displaced north and west (in southern Canada). Accordingly, 12Z high-resolution guidance continues to vary regarding storm coverage across the Slight Risk (isolated versus scattered) given the weaker forcing aloft. Even with this continued uncertainty, various NAM/RAP forecast soundings still suggest a somewhat conditional risk for organized storms (mix of multicells and supercells). Severe hail/wind may accompany the stronger storms from late afternoon through early evening, before this activity eventually weakens. Further south into the central/southern Plains, low-levels are forecast to be somewhat drier near the surface trough, with surface dewpoints expected to mostly range in the upper 50s to low 60s by late afternoon with pronounced boundary-layer mixing. Warmer mid-level temperatures and limited large-scale ascent across these regions should temper the overall intensity of any updrafts that can form and be sustained, and resultant intensity/coverage of this convection. Still, some guidance shows locally greater thunderstorm coverage and resulting isolated severe wind threat from the eastern TX Panhandle into far northwest OK and southern KS during the late afternoon/early evening, where low-level lapse rates should be maximized with robust daytime heating. ..Gleason/Moore.. 09/18/2024 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1118 AM CDT Wed Sep 18 2024 Valid 181700Z - 191200Z ...NO CRITICAL AREAS... ...17z Update... Morning observations show widespread precipitation greater than 0.1 inches, with pockets as high as 1-1.25 inches, has fallen over much of western SD and western NE in the last 72 hours. While some drier pockets remain, fuel guidance shows a notable decrease in dryness as a result. Meteorological conditions may still support some localized fire-weather concerns with strong southwesterly winds expected behind the surface low this afternoon. However, the strongest winds are likely to remain farther northwest where the heaviest precipitation has fallen. Gusty winds and humidity below 20% may support some drying today, but fuel recovery is expected to be modest such that no areas will be introduced. See the prior discussion for more information. ..Lyons.. 09/18/2024 .PREV DISCUSSION... /ISSUED 0154 AM CDT Wed Sep 18 2024/ ...Synopsis... A deep low-pressure system will move slowly east-northeastward over the northern High Plains through the period. On the backside of this system, a tight pressure gradient, and boundary-layer mixing into a belt of strong flow aloft, will yield strong post-frontal surface winds and 15-20 percent RH from eastern WY into the central Dakotas. While this would ordinarily support fire-weather concerns, precipitation over the past 24 hours should limit fuel receptiveness and the overall fire-weather threat. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1118 AM CDT Wed Sep 18 2024 Valid 181700Z - 191200Z ...NO CRITICAL AREAS... ...17z Update... Morning observations show widespread precipitation greater than 0.1 inches, with pockets as high as 1-1.25 inches, has fallen over much of western SD and western NE in the last 72 hours. While some drier pockets remain, fuel guidance shows a notable decrease in dryness as a result. Meteorological conditions may still support some localized fire-weather concerns with strong southwesterly winds expected behind the surface low this afternoon. However, the strongest winds are likely to remain farther northwest where the heaviest precipitation has fallen. Gusty winds and humidity below 20% may support some drying today, but fuel recovery is expected to be modest such that no areas will be introduced. See the prior discussion for more information. ..Lyons.. 09/18/2024 .PREV DISCUSSION... /ISSUED 0154 AM CDT Wed Sep 18 2024/ ...Synopsis... A deep low-pressure system will move slowly east-northeastward over the northern High Plains through the period. On the backside of this system, a tight pressure gradient, and boundary-layer mixing into a belt of strong flow aloft, will yield strong post-frontal surface winds and 15-20 percent RH from eastern WY into the central Dakotas. While this would ordinarily support fire-weather concerns, precipitation over the past 24 hours should limit fuel receptiveness and the overall fire-weather threat. ...Please see www.spc.noaa.gov/fire for graphic product... Read more