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SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0224 AM CDT Wed Sep 18 2024 Valid 201200Z - 211200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected on Friday. ...Discussion... A quiet pattern for severe potential is expected on Friday. A stout mid-level anticyclone will be anchored over the Lower Rio Grande Valley, with a ridge extending northeast to a separate anticyclone over QC. A surface cold front should slowly weaken and stall over the Upper Great Lakes to the Ozarks. In the wake of this front, low-level moisture will be limited downstream of an amplifying northern-stream shortwave trough across the Canadian Rockies into the southern Prairie Provinces. Mainly overnight elevated thunder potential is expected in the northern Great Plains. In the southern stream, a shortwave trough should slowly progress east across southern CA into AZ. Scant to meager buoyancy will preclude appreciable severe potential in the Southwest. But locally strong gusts will be possible with isolated high-based, low-topped thunderstorms around peak heating. ..Grams.. 09/18/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0224 AM CDT Wed Sep 18 2024 Valid 201200Z - 211200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected on Friday. ...Discussion... A quiet pattern for severe potential is expected on Friday. A stout mid-level anticyclone will be anchored over the Lower Rio Grande Valley, with a ridge extending northeast to a separate anticyclone over QC. A surface cold front should slowly weaken and stall over the Upper Great Lakes to the Ozarks. In the wake of this front, low-level moisture will be limited downstream of an amplifying northern-stream shortwave trough across the Canadian Rockies into the southern Prairie Provinces. Mainly overnight elevated thunder potential is expected in the northern Great Plains. In the southern stream, a shortwave trough should slowly progress east across southern CA into AZ. Scant to meager buoyancy will preclude appreciable severe potential in the Southwest. But locally strong gusts will be possible with isolated high-based, low-topped thunderstorms around peak heating. ..Grams.. 09/18/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0224 AM CDT Wed Sep 18 2024 Valid 201200Z - 211200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected on Friday. ...Discussion... A quiet pattern for severe potential is expected on Friday. A stout mid-level anticyclone will be anchored over the Lower Rio Grande Valley, with a ridge extending northeast to a separate anticyclone over QC. A surface cold front should slowly weaken and stall over the Upper Great Lakes to the Ozarks. In the wake of this front, low-level moisture will be limited downstream of an amplifying northern-stream shortwave trough across the Canadian Rockies into the southern Prairie Provinces. Mainly overnight elevated thunder potential is expected in the northern Great Plains. In the southern stream, a shortwave trough should slowly progress east across southern CA into AZ. Scant to meager buoyancy will preclude appreciable severe potential in the Southwest. But locally strong gusts will be possible with isolated high-based, low-topped thunderstorms around peak heating. ..Grams.. 09/18/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0224 AM CDT Wed Sep 18 2024 Valid 201200Z - 211200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected on Friday. ...Discussion... A quiet pattern for severe potential is expected on Friday. A stout mid-level anticyclone will be anchored over the Lower Rio Grande Valley, with a ridge extending northeast to a separate anticyclone over QC. A surface cold front should slowly weaken and stall over the Upper Great Lakes to the Ozarks. In the wake of this front, low-level moisture will be limited downstream of an amplifying northern-stream shortwave trough across the Canadian Rockies into the southern Prairie Provinces. Mainly overnight elevated thunder potential is expected in the northern Great Plains. In the southern stream, a shortwave trough should slowly progress east across southern CA into AZ. Scant to meager buoyancy will preclude appreciable severe potential in the Southwest. But locally strong gusts will be possible with isolated high-based, low-topped thunderstorms around peak heating. ..Grams.. 09/18/2024 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0154 AM CDT Wed Sep 18 2024 Valid 191200Z - 201200Z ...NO CRITICAL AREAS... ...Synopsis... In the wake of a midlevel low moving northeastward from the northern Plains into Canada, an expansive surface high will develop across much of the West. At the same time, a deep midlevel low and strong deep-layer southwesterly flow will overspread southern CA and the Lower CO River Valley. Overall, this pattern will limit the overlap of strong surface winds and warm/dry boundary-layer conditions atop dry fuels. ..Weinman.. 09/18/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0154 AM CDT Wed Sep 18 2024 Valid 191200Z - 201200Z ...NO CRITICAL AREAS... ...Synopsis... In the wake of a midlevel low moving northeastward from the northern Plains into Canada, an expansive surface high will develop across much of the West. At the same time, a deep midlevel low and strong deep-layer southwesterly flow will overspread southern CA and the Lower CO River Valley. Overall, this pattern will limit the overlap of strong surface winds and warm/dry boundary-layer conditions atop dry fuels. ..Weinman.. 09/18/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0154 AM CDT Wed Sep 18 2024 Valid 191200Z - 201200Z ...NO CRITICAL AREAS... ...Synopsis... In the wake of a midlevel low moving northeastward from the northern Plains into Canada, an expansive surface high will develop across much of the West. At the same time, a deep midlevel low and strong deep-layer southwesterly flow will overspread southern CA and the Lower CO River Valley. Overall, this pattern will limit the overlap of strong surface winds and warm/dry boundary-layer conditions atop dry fuels. ..Weinman.. 09/18/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0154 AM CDT Wed Sep 18 2024 Valid 191200Z - 201200Z ...NO CRITICAL AREAS... ...Synopsis... In the wake of a midlevel low moving northeastward from the northern Plains into Canada, an expansive surface high will develop across much of the West. At the same time, a deep midlevel low and strong deep-layer southwesterly flow will overspread southern CA and the Lower CO River Valley. Overall, this pattern will limit the overlap of strong surface winds and warm/dry boundary-layer conditions atop dry fuels. ..Weinman.. 09/18/2024 ...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 0154 AM CDT Wed Sep 18 2024 Valid 181200Z - 191200Z ...NO CRITICAL AREAS... ...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. ..Weinman.. 09/18/2024 ...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 0154 AM CDT Wed Sep 18 2024 Valid 181200Z - 191200Z ...NO CRITICAL AREAS... ...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. ..Weinman.. 09/18/2024 ...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 0154 AM CDT Wed Sep 18 2024 Valid 181200Z - 191200Z ...NO CRITICAL AREAS... ...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. ..Weinman.. 09/18/2024 ...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 0154 AM CDT Wed Sep 18 2024 Valid 181200Z - 191200Z ...NO CRITICAL AREAS... ...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. ..Weinman.. 09/18/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CDT Wed Sep 18 2024 Valid 191200Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN A PART OF THE UPPER MIDWEST... ...SUMMARY... Scattered severe thunderstorms are possible from mid-afternoon to mid-evening on Thursday across central/eastern Minnesota, northern Iowa, and western Wisconsin. A few tornadoes, isolated very large hail, and damaging winds may occur. ...Upper Midwest... A vertically stacked cyclone near the ND/SK/MB border area on Thursday morning will advance northeast across MB through the period. Mid-level west-southwesterlies will remain enhanced (35-50 kt from 700-500 mb) through the afternoon to the south-southeast of this cyclone, before the system as a whole weakens and progresses farther away from the Upper Midwest. At the surface, a cold front will arc south, and progress east over MN/IA. Ahead of the front, a confined plume of mid to upper 60s surface dew points will be maintained, but will decrease within a drier boundary layer deeper into WI and IL. The aforementioned flow regime will yield initially steep mid-level lapse rates from 7-8 C/km through early afternoon. Coupled with the rich buoyancy plume, moderate to large MLCAPE of 2000-3000 J/kg appears plausible, northeast of the Mid-MO Valley. Guidance spread does exist with the timing and related spatial placement of initial thunderstorm development along the front. Some models suggest scattered convection should form during the early to mid afternoon, while others are delayed until the late afternoon. This may be related to the strength of the elevated mixed layer and timing of weakened MLCIN. This uncertainty within a limited longitudinal extent of greater threat, precludes a level 3-ENH risk. The conditional large to very large hail threat appears favorable amid a vertically veering wind profile with height that will support initial supercells. While some clustering is possible owing to frontal convergence, the bulk of severe convection may remain tied to semi-discrete supercells given the nearly perpendicular mid-level wind profile to the front and moderately enlarged low-level hodograph. This should support potential for a few tornadoes as well. Clustering should become more prominent after sunset, but the severe threat is expected to diminish soon after dusk as activity outpaces the nocturnally shrinking buoyancy plume. ..Grams.. 09/18/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CDT Wed Sep 18 2024 Valid 191200Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN A PART OF THE UPPER MIDWEST... ...SUMMARY... Scattered severe thunderstorms are possible from mid-afternoon to mid-evening on Thursday across central/eastern Minnesota, northern Iowa, and western Wisconsin. A few tornadoes, isolated very large hail, and damaging winds may occur. ...Upper Midwest... A vertically stacked cyclone near the ND/SK/MB border area on Thursday morning will advance northeast across MB through the period. Mid-level west-southwesterlies will remain enhanced (35-50 kt from 700-500 mb) through the afternoon to the south-southeast of this cyclone, before the system as a whole weakens and progresses farther away from the Upper Midwest. At the surface, a cold front will arc south, and progress east over MN/IA. Ahead of the front, a confined plume of mid to upper 60s surface dew points will be maintained, but will decrease within a drier boundary layer deeper into WI and IL. The aforementioned flow regime will yield initially steep mid-level lapse rates from 7-8 C/km through early afternoon. Coupled with the rich buoyancy plume, moderate to large MLCAPE of 2000-3000 J/kg appears plausible, northeast of the Mid-MO Valley. Guidance spread does exist with the timing and related spatial placement of initial thunderstorm development along the front. Some models suggest scattered convection should form during the early to mid afternoon, while others are delayed until the late afternoon. This may be related to the strength of the elevated mixed layer and timing of weakened MLCIN. This uncertainty within a limited longitudinal extent of greater threat, precludes a level 3-ENH risk. The conditional large to very large hail threat appears favorable amid a vertically veering wind profile with height that will support initial supercells. While some clustering is possible owing to frontal convergence, the bulk of severe convection may remain tied to semi-discrete supercells given the nearly perpendicular mid-level wind profile to the front and moderately enlarged low-level hodograph. This should support potential for a few tornadoes as well. Clustering should become more prominent after sunset, but the severe threat is expected to diminish soon after dusk as activity outpaces the nocturnally shrinking buoyancy plume. ..Grams.. 09/18/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CDT Wed Sep 18 2024 Valid 191200Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN A PART OF THE UPPER MIDWEST... ...SUMMARY... Scattered severe thunderstorms are possible from mid-afternoon to mid-evening on Thursday across central/eastern Minnesota, northern Iowa, and western Wisconsin. A few tornadoes, isolated very large hail, and damaging winds may occur. ...Upper Midwest... A vertically stacked cyclone near the ND/SK/MB border area on Thursday morning will advance northeast across MB through the period. Mid-level west-southwesterlies will remain enhanced (35-50 kt from 700-500 mb) through the afternoon to the south-southeast of this cyclone, before the system as a whole weakens and progresses farther away from the Upper Midwest. At the surface, a cold front will arc south, and progress east over MN/IA. Ahead of the front, a confined plume of mid to upper 60s surface dew points will be maintained, but will decrease within a drier boundary layer deeper into WI and IL. The aforementioned flow regime will yield initially steep mid-level lapse rates from 7-8 C/km through early afternoon. Coupled with the rich buoyancy plume, moderate to large MLCAPE of 2000-3000 J/kg appears plausible, northeast of the Mid-MO Valley. Guidance spread does exist with the timing and related spatial placement of initial thunderstorm development along the front. Some models suggest scattered convection should form during the early to mid afternoon, while others are delayed until the late afternoon. This may be related to the strength of the elevated mixed layer and timing of weakened MLCIN. This uncertainty within a limited longitudinal extent of greater threat, precludes a level 3-ENH risk. The conditional large to very large hail threat appears favorable amid a vertically veering wind profile with height that will support initial supercells. While some clustering is possible owing to frontal convergence, the bulk of severe convection may remain tied to semi-discrete supercells given the nearly perpendicular mid-level wind profile to the front and moderately enlarged low-level hodograph. This should support potential for a few tornadoes as well. Clustering should become more prominent after sunset, but the severe threat is expected to diminish soon after dusk as activity outpaces the nocturnally shrinking buoyancy plume. ..Grams.. 09/18/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CDT Wed Sep 18 2024 Valid 191200Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN A PART OF THE UPPER MIDWEST... ...SUMMARY... Scattered severe thunderstorms are possible from mid-afternoon to mid-evening on Thursday across central/eastern Minnesota, northern Iowa, and western Wisconsin. A few tornadoes, isolated very large hail, and damaging winds may occur. ...Upper Midwest... A vertically stacked cyclone near the ND/SK/MB border area on Thursday morning will advance northeast across MB through the period. Mid-level west-southwesterlies will remain enhanced (35-50 kt from 700-500 mb) through the afternoon to the south-southeast of this cyclone, before the system as a whole weakens and progresses farther away from the Upper Midwest. At the surface, a cold front will arc south, and progress east over MN/IA. Ahead of the front, a confined plume of mid to upper 60s surface dew points will be maintained, but will decrease within a drier boundary layer deeper into WI and IL. The aforementioned flow regime will yield initially steep mid-level lapse rates from 7-8 C/km through early afternoon. Coupled with the rich buoyancy plume, moderate to large MLCAPE of 2000-3000 J/kg appears plausible, northeast of the Mid-MO Valley. Guidance spread does exist with the timing and related spatial placement of initial thunderstorm development along the front. Some models suggest scattered convection should form during the early to mid afternoon, while others are delayed until the late afternoon. This may be related to the strength of the elevated mixed layer and timing of weakened MLCIN. This uncertainty within a limited longitudinal extent of greater threat, precludes a level 3-ENH risk. The conditional large to very large hail threat appears favorable amid a vertically veering wind profile with height that will support initial supercells. While some clustering is possible owing to frontal convergence, the bulk of severe convection may remain tied to semi-discrete supercells given the nearly perpendicular mid-level wind profile to the front and moderately enlarged low-level hodograph. This should support potential for a few tornadoes as well. Clustering should become more prominent after sunset, but the severe threat is expected to diminish soon after dusk as activity outpaces the nocturnally shrinking buoyancy plume. ..Grams.. 09/18/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1258 AM CDT Wed Sep 18 2024 Valid 181200Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE MID MISSOURI VALLEY NORTHWARD INTO EASTERN SOUTH DAKOTA AND WESTERN MINNESOTA... ...SUMMARY... Thunderstorms capable of severe wind gusts and isolated large hail are possible today across parts of the eastern Dakotas and Minnesota southward in the mid Missouri Valley. A marginal severe threat will also be possible in parts of the central and southern Plains. ...Northern Plains/Upper Mississippi Valley/Mid Missouri Valley... An upper-level low will move northeastward through the northern High Plains today, as an associated mid-level speed max translates northeastward through the northern Plains. At the surface, a low will move through northeastern Montana, with a trough extending southward across the High Plains. To the east of the trough in the mid Missouri Valley and northern Plains, surface dewpoints will generally be in the lower to mid 60s F. As surface temperatures warm today, moderate instability will develop within a narrow corridor from eastern Nebraska northward into the eastern Dakotas. Isolated to scattered thunderstorms are expected to form to the east of the surface trough near the instability axis during the afternoon. These storms will move northeastward across the eastern portion of the central and northern Plains during the late afternoon and evening. RAP forecast soundings at 00Z/Thu near the instability axis at Sioux Falls, South Dakota have 0-6 km shear in the 30 to 35 knot range. Some speed shear is evident in lowest 3 km, and low-level lapse rates are forecast to be steep, peaking in the 7.5 to 8 C/km range. This environment should support supercell development during the late afternoon and early evening. Supercells will likely be capable of producing severe wind gusts and isolated large hail. Further south into the southern and central Plains, low-levels are forecast to be drier near the surface trough, with dewpoints expected to be mostly in the upper 50s and lower 60s F. For this reason, instability is expected to remain relative weak today. This, combined with limited large-scale ascent will likely keep any severe threat isolated and marginal. ..Broyles/Weinman.. 09/18/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1258 AM CDT Wed Sep 18 2024 Valid 181200Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE MID MISSOURI VALLEY NORTHWARD INTO EASTERN SOUTH DAKOTA AND WESTERN MINNESOTA... ...SUMMARY... Thunderstorms capable of severe wind gusts and isolated large hail are possible today across parts of the eastern Dakotas and Minnesota southward in the mid Missouri Valley. A marginal severe threat will also be possible in parts of the central and southern Plains. ...Northern Plains/Upper Mississippi Valley/Mid Missouri Valley... An upper-level low will move northeastward through the northern High Plains today, as an associated mid-level speed max translates northeastward through the northern Plains. At the surface, a low will move through northeastern Montana, with a trough extending southward across the High Plains. To the east of the trough in the mid Missouri Valley and northern Plains, surface dewpoints will generally be in the lower to mid 60s F. As surface temperatures warm today, moderate instability will develop within a narrow corridor from eastern Nebraska northward into the eastern Dakotas. Isolated to scattered thunderstorms are expected to form to the east of the surface trough near the instability axis during the afternoon. These storms will move northeastward across the eastern portion of the central and northern Plains during the late afternoon and evening. RAP forecast soundings at 00Z/Thu near the instability axis at Sioux Falls, South Dakota have 0-6 km shear in the 30 to 35 knot range. Some speed shear is evident in lowest 3 km, and low-level lapse rates are forecast to be steep, peaking in the 7.5 to 8 C/km range. This environment should support supercell development during the late afternoon and early evening. Supercells will likely be capable of producing severe wind gusts and isolated large hail. Further south into the southern and central Plains, low-levels are forecast to be drier near the surface trough, with dewpoints expected to be mostly in the upper 50s and lower 60s F. For this reason, instability is expected to remain relative weak today. This, combined with limited large-scale ascent will likely keep any severe threat isolated and marginal. ..Broyles/Weinman.. 09/18/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1258 AM CDT Wed Sep 18 2024 Valid 181200Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE MID MISSOURI VALLEY NORTHWARD INTO EASTERN SOUTH DAKOTA AND WESTERN MINNESOTA... ...SUMMARY... Thunderstorms capable of severe wind gusts and isolated large hail are possible today across parts of the eastern Dakotas and Minnesota southward in the mid Missouri Valley. A marginal severe threat will also be possible in parts of the central and southern Plains. ...Northern Plains/Upper Mississippi Valley/Mid Missouri Valley... An upper-level low will move northeastward through the northern High Plains today, as an associated mid-level speed max translates northeastward through the northern Plains. At the surface, a low will move through northeastern Montana, with a trough extending southward across the High Plains. To the east of the trough in the mid Missouri Valley and northern Plains, surface dewpoints will generally be in the lower to mid 60s F. As surface temperatures warm today, moderate instability will develop within a narrow corridor from eastern Nebraska northward into the eastern Dakotas. Isolated to scattered thunderstorms are expected to form to the east of the surface trough near the instability axis during the afternoon. These storms will move northeastward across the eastern portion of the central and northern Plains during the late afternoon and evening. RAP forecast soundings at 00Z/Thu near the instability axis at Sioux Falls, South Dakota have 0-6 km shear in the 30 to 35 knot range. Some speed shear is evident in lowest 3 km, and low-level lapse rates are forecast to be steep, peaking in the 7.5 to 8 C/km range. This environment should support supercell development during the late afternoon and early evening. Supercells will likely be capable of producing severe wind gusts and isolated large hail. Further south into the southern and central Plains, low-levels are forecast to be drier near the surface trough, with dewpoints expected to be mostly in the upper 50s and lower 60s F. For this reason, instability is expected to remain relative weak today. This, combined with limited large-scale ascent will likely keep any severe threat isolated and marginal. ..Broyles/Weinman.. 09/18/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1258 AM CDT Wed Sep 18 2024 Valid 181200Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE MID MISSOURI VALLEY NORTHWARD INTO EASTERN SOUTH DAKOTA AND WESTERN MINNESOTA... ...SUMMARY... Thunderstorms capable of severe wind gusts and isolated large hail are possible today across parts of the eastern Dakotas and Minnesota southward in the mid Missouri Valley. A marginal severe threat will also be possible in parts of the central and southern Plains. ...Northern Plains/Upper Mississippi Valley/Mid Missouri Valley... An upper-level low will move northeastward through the northern High Plains today, as an associated mid-level speed max translates northeastward through the northern Plains. At the surface, a low will move through northeastern Montana, with a trough extending southward across the High Plains. To the east of the trough in the mid Missouri Valley and northern Plains, surface dewpoints will generally be in the lower to mid 60s F. As surface temperatures warm today, moderate instability will develop within a narrow corridor from eastern Nebraska northward into the eastern Dakotas. Isolated to scattered thunderstorms are expected to form to the east of the surface trough near the instability axis during the afternoon. These storms will move northeastward across the eastern portion of the central and northern Plains during the late afternoon and evening. RAP forecast soundings at 00Z/Thu near the instability axis at Sioux Falls, South Dakota have 0-6 km shear in the 30 to 35 knot range. Some speed shear is evident in lowest 3 km, and low-level lapse rates are forecast to be steep, peaking in the 7.5 to 8 C/km range. This environment should support supercell development during the late afternoon and early evening. Supercells will likely be capable of producing severe wind gusts and isolated large hail. Further south into the southern and central Plains, low-levels are forecast to be drier near the surface trough, with dewpoints expected to be mostly in the upper 50s and lower 60s F. For this reason, instability is expected to remain relative weak today. This, combined with limited large-scale ascent will likely keep any severe threat isolated and marginal. ..Broyles/Weinman.. 09/18/2024 Read more