Severe Storms

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0256 PM CDT Mon Aug 11 2025 Valid 112000Z - 121200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE SOUTHERN GREAT PLAINS...LOWER MISSOURI VALLEY...AND UPPER MIDWEST...... ...SUMMARY... Isolated strong to severe thunderstorms are possible across parts of the southern Plains, lower Missouri Valley, and the Upper Midwest, mainly this afternoon and evening. ...20Z Update... Other than updates to the general thunderstorm forecast, the outlook remains unchanged. See the previous discussion for more details. ..Wendt.. 08/11/2025 .PREV DISCUSSION... /ISSUED 1112 AM CDT Mon Aug 11 2025/ ...Lower MO Valley... Visible satellite/radar composite shows an MCV moving east-northeastward over northeast KS late this morning. Regional WSR-88D VAD data shows an enhanced belt of 850-500 mb flow (40 kt in the 2-6 km layer) associated with this disturbance. Surface analysis places a surface low over the Flint Hills with backed easterly flow across eastern KS into northwest MO. Considerable mid- to high-level cloud debris from early morning convection will be slow to dissipate, but gradual filtering of sunlight and the initial signs of a stratocumulus field over the Flint Hills indicates destabilization is beginning to occur. Models vary considerably (understandably so) regarding the development/evolution of a few potential stronger thunderstorms across the lower MO Valley later this afternoon into the early evening. Some forecast soundings show modest enlargement of the low-level portion of the hodograph, which may support updraft rotation if vigorous updraft development occurs. Given the low probability for severe and potentially supportive environment, have introduced low-severe probabilities this outlook update. ...Southern Plains... Morning analysis shows an outflow reinforced front has advanced southward across the southern High Plains, but has stalled near the I-44 corridor in OK southwestward into the northern periphery of the Permian Basin. Water-vapor imagery shows a mid-level impulse moving across southern CO and embedded within larger-scale troughing from CO/NM into the Upper Midwest. This mid-level trough will gradually pivot eastward over the southern High Plains through the evening. Heating of an adequately moist boundary layer (dewpoints ranging from the lower 70s in central OK to the mid 50s in east-central NM) will yield moderate buoyancy near/north of the diffuse boundary. Weak low-level winds will gradually veer to west-northwesterly and modestly strengthen with height through mid/upper levels, supporting modest deep-layer shear and some updraft organization. Isolated severe hail may occur with initially more cellular development across the southern High Plains, before some clustering potentially occurs late this afternoon/evening farther east into the TX Panhandle and northwest TX with more of a wind threat. While deep-layer shear will likely remain weak farther east across OK, the front/outflow boundary should aid in at least scattered thunderstorms. Isolated large hail and severe gusts are the primary hazards with the stronger thunderstorms. ...North Dakota into Northern Minnesota... No change in thinking from the previous forecast. A mid-level shortwave trough and related surface cold front are forecast to move east-southeastward over ND and northern MN through the period. Modest low-level moisture characterized by mid 50s to perhaps low 60s surface dewpoints should be present ahead of the front across these areas. Diurnal heating and modestly steepened lapse rates aloft should aid in the development of weak instability this afternoon. Thunderstorms should gradually increase in coverage along/ahead of the front this afternoon/evening as they spread eastward over parts of ND into northern MN. The stronger cells may produce marginally severe hail, with sufficient deep-layer shear present for some convective organization. With time, some clustering/upscale growth along the front appears probable, with isolated strong to severe gusts possible. The lack of stronger instability should tend to temper the overall severe threat. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0256 PM CDT Mon Aug 11 2025 Valid 112000Z - 121200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE SOUTHERN GREAT PLAINS...LOWER MISSOURI VALLEY...AND UPPER MIDWEST...... ...SUMMARY... Isolated strong to severe thunderstorms are possible across parts of the southern Plains, lower Missouri Valley, and the Upper Midwest, mainly this afternoon and evening. ...20Z Update... Other than updates to the general thunderstorm forecast, the outlook remains unchanged. See the previous discussion for more details. ..Wendt.. 08/11/2025 .PREV DISCUSSION... /ISSUED 1112 AM CDT Mon Aug 11 2025/ ...Lower MO Valley... Visible satellite/radar composite shows an MCV moving east-northeastward over northeast KS late this morning. Regional WSR-88D VAD data shows an enhanced belt of 850-500 mb flow (40 kt in the 2-6 km layer) associated with this disturbance. Surface analysis places a surface low over the Flint Hills with backed easterly flow across eastern KS into northwest MO. Considerable mid- to high-level cloud debris from early morning convection will be slow to dissipate, but gradual filtering of sunlight and the initial signs of a stratocumulus field over the Flint Hills indicates destabilization is beginning to occur. Models vary considerably (understandably so) regarding the development/evolution of a few potential stronger thunderstorms across the lower MO Valley later this afternoon into the early evening. Some forecast soundings show modest enlargement of the low-level portion of the hodograph, which may support updraft rotation if vigorous updraft development occurs. Given the low probability for severe and potentially supportive environment, have introduced low-severe probabilities this outlook update. ...Southern Plains... Morning analysis shows an outflow reinforced front has advanced southward across the southern High Plains, but has stalled near the I-44 corridor in OK southwestward into the northern periphery of the Permian Basin. Water-vapor imagery shows a mid-level impulse moving across southern CO and embedded within larger-scale troughing from CO/NM into the Upper Midwest. This mid-level trough will gradually pivot eastward over the southern High Plains through the evening. Heating of an adequately moist boundary layer (dewpoints ranging from the lower 70s in central OK to the mid 50s in east-central NM) will yield moderate buoyancy near/north of the diffuse boundary. Weak low-level winds will gradually veer to west-northwesterly and modestly strengthen with height through mid/upper levels, supporting modest deep-layer shear and some updraft organization. Isolated severe hail may occur with initially more cellular development across the southern High Plains, before some clustering potentially occurs late this afternoon/evening farther east into the TX Panhandle and northwest TX with more of a wind threat. While deep-layer shear will likely remain weak farther east across OK, the front/outflow boundary should aid in at least scattered thunderstorms. Isolated large hail and severe gusts are the primary hazards with the stronger thunderstorms. ...North Dakota into Northern Minnesota... No change in thinking from the previous forecast. A mid-level shortwave trough and related surface cold front are forecast to move east-southeastward over ND and northern MN through the period. Modest low-level moisture characterized by mid 50s to perhaps low 60s surface dewpoints should be present ahead of the front across these areas. Diurnal heating and modestly steepened lapse rates aloft should aid in the development of weak instability this afternoon. Thunderstorms should gradually increase in coverage along/ahead of the front this afternoon/evening as they spread eastward over parts of ND into northern MN. The stronger cells may produce marginally severe hail, with sufficient deep-layer shear present for some convective organization. With time, some clustering/upscale growth along the front appears probable, with isolated strong to severe gusts possible. The lack of stronger instability should tend to temper the overall severe threat. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0256 PM CDT Mon Aug 11 2025 Valid 112000Z - 121200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE SOUTHERN GREAT PLAINS...LOWER MISSOURI VALLEY...AND UPPER MIDWEST...... ...SUMMARY... Isolated strong to severe thunderstorms are possible across parts of the southern Plains, lower Missouri Valley, and the Upper Midwest, mainly this afternoon and evening. ...20Z Update... Other than updates to the general thunderstorm forecast, the outlook remains unchanged. See the previous discussion for more details. ..Wendt.. 08/11/2025 .PREV DISCUSSION... /ISSUED 1112 AM CDT Mon Aug 11 2025/ ...Lower MO Valley... Visible satellite/radar composite shows an MCV moving east-northeastward over northeast KS late this morning. Regional WSR-88D VAD data shows an enhanced belt of 850-500 mb flow (40 kt in the 2-6 km layer) associated with this disturbance. Surface analysis places a surface low over the Flint Hills with backed easterly flow across eastern KS into northwest MO. Considerable mid- to high-level cloud debris from early morning convection will be slow to dissipate, but gradual filtering of sunlight and the initial signs of a stratocumulus field over the Flint Hills indicates destabilization is beginning to occur. Models vary considerably (understandably so) regarding the development/evolution of a few potential stronger thunderstorms across the lower MO Valley later this afternoon into the early evening. Some forecast soundings show modest enlargement of the low-level portion of the hodograph, which may support updraft rotation if vigorous updraft development occurs. Given the low probability for severe and potentially supportive environment, have introduced low-severe probabilities this outlook update. ...Southern Plains... Morning analysis shows an outflow reinforced front has advanced southward across the southern High Plains, but has stalled near the I-44 corridor in OK southwestward into the northern periphery of the Permian Basin. Water-vapor imagery shows a mid-level impulse moving across southern CO and embedded within larger-scale troughing from CO/NM into the Upper Midwest. This mid-level trough will gradually pivot eastward over the southern High Plains through the evening. Heating of an adequately moist boundary layer (dewpoints ranging from the lower 70s in central OK to the mid 50s in east-central NM) will yield moderate buoyancy near/north of the diffuse boundary. Weak low-level winds will gradually veer to west-northwesterly and modestly strengthen with height through mid/upper levels, supporting modest deep-layer shear and some updraft organization. Isolated severe hail may occur with initially more cellular development across the southern High Plains, before some clustering potentially occurs late this afternoon/evening farther east into the TX Panhandle and northwest TX with more of a wind threat. While deep-layer shear will likely remain weak farther east across OK, the front/outflow boundary should aid in at least scattered thunderstorms. Isolated large hail and severe gusts are the primary hazards with the stronger thunderstorms. ...North Dakota into Northern Minnesota... No change in thinking from the previous forecast. A mid-level shortwave trough and related surface cold front are forecast to move east-southeastward over ND and northern MN through the period. Modest low-level moisture characterized by mid 50s to perhaps low 60s surface dewpoints should be present ahead of the front across these areas. Diurnal heating and modestly steepened lapse rates aloft should aid in the development of weak instability this afternoon. Thunderstorms should gradually increase in coverage along/ahead of the front this afternoon/evening as they spread eastward over parts of ND into northern MN. The stronger cells may produce marginally severe hail, with sufficient deep-layer shear present for some convective organization. With time, some clustering/upscale growth along the front appears probable, with isolated strong to severe gusts possible. The lack of stronger instability should tend to temper the overall severe threat. Read more

No Mesoscale Discussions are in effect as of Mon Aug 11 20:01:02 UTC 2025.

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0251 PM CDT Mon Aug 11 2025 Valid 121200Z - 131200Z Only minor adjustments were made to the D2 Fire Outlook Isolated Dry Thunderstorm area to expand into north-western Arizona in alignment with recent hi-res guidance. See previous discussion below for more information. ..Thornton.. 08/11/2025 .PREV DISCUSSION... /ISSUED 0135 AM CDT Mon Aug 11 2025/ ...Synopsis... Isolated dry thunderstorms will remain the primary fire weather concern for Tuesday across the country. Latest forecast guidance hints that a deeply-mixed, but adequately buoyant, environment will remain in place across central AZ on the northern fringe of deeper monsoonal moisture. Forcing for ascent will be fairly weak and largely driven by orographic ascent along the Mogollon Rim. However, several deterministic CAM and recent HREF guidance hints at the potential for at least a few thunderstorms. This thermodynamic environment has yielded a mixture of wet and dry thunderstorms over the past 24 hours, so a similar combination appears probable for Tuesday. Fine fuels largely remain dry across the region, and recent lightning-caused fires hint that the fuel environment should support at least some fire starts. ...Pacific Northwest... A weak mid-level trough is forecast to move across the Pacific Northwest on Tuesday. While flow aloft will be fairly modest, the zonal flow over the Cascades and northern Sierra Nevada will likely induce a downslope flow regime within an antecedent dry environment with receptive fuels. Ensemble support was too limited to warrant additional highlights, but localized elevated fire weather conditions appear possible across far northwest NV, eastern OR, and southern WA Tuesday afternoon. ...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 0251 PM CDT Mon Aug 11 2025 Valid 121200Z - 131200Z Only minor adjustments were made to the D2 Fire Outlook Isolated Dry Thunderstorm area to expand into north-western Arizona in alignment with recent hi-res guidance. See previous discussion below for more information. ..Thornton.. 08/11/2025 .PREV DISCUSSION... /ISSUED 0135 AM CDT Mon Aug 11 2025/ ...Synopsis... Isolated dry thunderstorms will remain the primary fire weather concern for Tuesday across the country. Latest forecast guidance hints that a deeply-mixed, but adequately buoyant, environment will remain in place across central AZ on the northern fringe of deeper monsoonal moisture. Forcing for ascent will be fairly weak and largely driven by orographic ascent along the Mogollon Rim. However, several deterministic CAM and recent HREF guidance hints at the potential for at least a few thunderstorms. This thermodynamic environment has yielded a mixture of wet and dry thunderstorms over the past 24 hours, so a similar combination appears probable for Tuesday. Fine fuels largely remain dry across the region, and recent lightning-caused fires hint that the fuel environment should support at least some fire starts. ...Pacific Northwest... A weak mid-level trough is forecast to move across the Pacific Northwest on Tuesday. While flow aloft will be fairly modest, the zonal flow over the Cascades and northern Sierra Nevada will likely induce a downslope flow regime within an antecedent dry environment with receptive fuels. Ensemble support was too limited to warrant additional highlights, but localized elevated fire weather conditions appear possible across far northwest NV, eastern OR, and southern WA Tuesday afternoon. ...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 0251 PM CDT Mon Aug 11 2025 Valid 121200Z - 131200Z Only minor adjustments were made to the D2 Fire Outlook Isolated Dry Thunderstorm area to expand into north-western Arizona in alignment with recent hi-res guidance. See previous discussion below for more information. ..Thornton.. 08/11/2025 .PREV DISCUSSION... /ISSUED 0135 AM CDT Mon Aug 11 2025/ ...Synopsis... Isolated dry thunderstorms will remain the primary fire weather concern for Tuesday across the country. Latest forecast guidance hints that a deeply-mixed, but adequately buoyant, environment will remain in place across central AZ on the northern fringe of deeper monsoonal moisture. Forcing for ascent will be fairly weak and largely driven by orographic ascent along the Mogollon Rim. However, several deterministic CAM and recent HREF guidance hints at the potential for at least a few thunderstorms. This thermodynamic environment has yielded a mixture of wet and dry thunderstorms over the past 24 hours, so a similar combination appears probable for Tuesday. Fine fuels largely remain dry across the region, and recent lightning-caused fires hint that the fuel environment should support at least some fire starts. ...Pacific Northwest... A weak mid-level trough is forecast to move across the Pacific Northwest on Tuesday. While flow aloft will be fairly modest, the zonal flow over the Cascades and northern Sierra Nevada will likely induce a downslope flow regime within an antecedent dry environment with receptive fuels. Ensemble support was too limited to warrant additional highlights, but localized elevated fire weather conditions appear possible across far northwest NV, eastern OR, and southern WA Tuesday afternoon. ...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 0251 PM CDT Mon Aug 11 2025 Valid 121200Z - 131200Z Only minor adjustments were made to the D2 Fire Outlook Isolated Dry Thunderstorm area to expand into north-western Arizona in alignment with recent hi-res guidance. See previous discussion below for more information. ..Thornton.. 08/11/2025 .PREV DISCUSSION... /ISSUED 0135 AM CDT Mon Aug 11 2025/ ...Synopsis... Isolated dry thunderstorms will remain the primary fire weather concern for Tuesday across the country. Latest forecast guidance hints that a deeply-mixed, but adequately buoyant, environment will remain in place across central AZ on the northern fringe of deeper monsoonal moisture. Forcing for ascent will be fairly weak and largely driven by orographic ascent along the Mogollon Rim. However, several deterministic CAM and recent HREF guidance hints at the potential for at least a few thunderstorms. This thermodynamic environment has yielded a mixture of wet and dry thunderstorms over the past 24 hours, so a similar combination appears probable for Tuesday. Fine fuels largely remain dry across the region, and recent lightning-caused fires hint that the fuel environment should support at least some fire starts. ...Pacific Northwest... A weak mid-level trough is forecast to move across the Pacific Northwest on Tuesday. While flow aloft will be fairly modest, the zonal flow over the Cascades and northern Sierra Nevada will likely induce a downslope flow regime within an antecedent dry environment with receptive fuels. Ensemble support was too limited to warrant additional highlights, but localized elevated fire weather conditions appear possible across far northwest NV, eastern OR, and southern WA Tuesday afternoon. ...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 0251 PM CDT Mon Aug 11 2025 Valid 121200Z - 131200Z Only minor adjustments were made to the D2 Fire Outlook Isolated Dry Thunderstorm area to expand into north-western Arizona in alignment with recent hi-res guidance. See previous discussion below for more information. ..Thornton.. 08/11/2025 .PREV DISCUSSION... /ISSUED 0135 AM CDT Mon Aug 11 2025/ ...Synopsis... Isolated dry thunderstorms will remain the primary fire weather concern for Tuesday across the country. Latest forecast guidance hints that a deeply-mixed, but adequately buoyant, environment will remain in place across central AZ on the northern fringe of deeper monsoonal moisture. Forcing for ascent will be fairly weak and largely driven by orographic ascent along the Mogollon Rim. However, several deterministic CAM and recent HREF guidance hints at the potential for at least a few thunderstorms. This thermodynamic environment has yielded a mixture of wet and dry thunderstorms over the past 24 hours, so a similar combination appears probable for Tuesday. Fine fuels largely remain dry across the region, and recent lightning-caused fires hint that the fuel environment should support at least some fire starts. ...Pacific Northwest... A weak mid-level trough is forecast to move across the Pacific Northwest on Tuesday. While flow aloft will be fairly modest, the zonal flow over the Cascades and northern Sierra Nevada will likely induce a downslope flow regime within an antecedent dry environment with receptive fuels. Ensemble support was too limited to warrant additional highlights, but localized elevated fire weather conditions appear possible across far northwest NV, eastern OR, and southern WA Tuesday afternoon. ...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 0251 PM CDT Mon Aug 11 2025 Valid 121200Z - 131200Z Only minor adjustments were made to the D2 Fire Outlook Isolated Dry Thunderstorm area to expand into north-western Arizona in alignment with recent hi-res guidance. See previous discussion below for more information. ..Thornton.. 08/11/2025 .PREV DISCUSSION... /ISSUED 0135 AM CDT Mon Aug 11 2025/ ...Synopsis... Isolated dry thunderstorms will remain the primary fire weather concern for Tuesday across the country. Latest forecast guidance hints that a deeply-mixed, but adequately buoyant, environment will remain in place across central AZ on the northern fringe of deeper monsoonal moisture. Forcing for ascent will be fairly weak and largely driven by orographic ascent along the Mogollon Rim. However, several deterministic CAM and recent HREF guidance hints at the potential for at least a few thunderstorms. This thermodynamic environment has yielded a mixture of wet and dry thunderstorms over the past 24 hours, so a similar combination appears probable for Tuesday. Fine fuels largely remain dry across the region, and recent lightning-caused fires hint that the fuel environment should support at least some fire starts. ...Pacific Northwest... A weak mid-level trough is forecast to move across the Pacific Northwest on Tuesday. While flow aloft will be fairly modest, the zonal flow over the Cascades and northern Sierra Nevada will likely induce a downslope flow regime within an antecedent dry environment with receptive fuels. Ensemble support was too limited to warrant additional highlights, but localized elevated fire weather conditions appear possible across far northwest NV, eastern OR, and southern WA Tuesday afternoon. ...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 0251 PM CDT Mon Aug 11 2025 Valid 121200Z - 131200Z Only minor adjustments were made to the D2 Fire Outlook Isolated Dry Thunderstorm area to expand into north-western Arizona in alignment with recent hi-res guidance. See previous discussion below for more information. ..Thornton.. 08/11/2025 .PREV DISCUSSION... /ISSUED 0135 AM CDT Mon Aug 11 2025/ ...Synopsis... Isolated dry thunderstorms will remain the primary fire weather concern for Tuesday across the country. Latest forecast guidance hints that a deeply-mixed, but adequately buoyant, environment will remain in place across central AZ on the northern fringe of deeper monsoonal moisture. Forcing for ascent will be fairly weak and largely driven by orographic ascent along the Mogollon Rim. However, several deterministic CAM and recent HREF guidance hints at the potential for at least a few thunderstorms. This thermodynamic environment has yielded a mixture of wet and dry thunderstorms over the past 24 hours, so a similar combination appears probable for Tuesday. Fine fuels largely remain dry across the region, and recent lightning-caused fires hint that the fuel environment should support at least some fire starts. ...Pacific Northwest... A weak mid-level trough is forecast to move across the Pacific Northwest on Tuesday. While flow aloft will be fairly modest, the zonal flow over the Cascades and northern Sierra Nevada will likely induce a downslope flow regime within an antecedent dry environment with receptive fuels. Ensemble support was too limited to warrant additional highlights, but localized elevated fire weather conditions appear possible across far northwest NV, eastern OR, and southern WA Tuesday afternoon. ...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 0251 PM CDT Mon Aug 11 2025 Valid 121200Z - 131200Z Only minor adjustments were made to the D2 Fire Outlook Isolated Dry Thunderstorm area to expand into north-western Arizona in alignment with recent hi-res guidance. See previous discussion below for more information. ..Thornton.. 08/11/2025 .PREV DISCUSSION... /ISSUED 0135 AM CDT Mon Aug 11 2025/ ...Synopsis... Isolated dry thunderstorms will remain the primary fire weather concern for Tuesday across the country. Latest forecast guidance hints that a deeply-mixed, but adequately buoyant, environment will remain in place across central AZ on the northern fringe of deeper monsoonal moisture. Forcing for ascent will be fairly weak and largely driven by orographic ascent along the Mogollon Rim. However, several deterministic CAM and recent HREF guidance hints at the potential for at least a few thunderstorms. This thermodynamic environment has yielded a mixture of wet and dry thunderstorms over the past 24 hours, so a similar combination appears probable for Tuesday. Fine fuels largely remain dry across the region, and recent lightning-caused fires hint that the fuel environment should support at least some fire starts. ...Pacific Northwest... A weak mid-level trough is forecast to move across the Pacific Northwest on Tuesday. While flow aloft will be fairly modest, the zonal flow over the Cascades and northern Sierra Nevada will likely induce a downslope flow regime within an antecedent dry environment with receptive fuels. Ensemble support was too limited to warrant additional highlights, but localized elevated fire weather conditions appear possible across far northwest NV, eastern OR, and southern WA Tuesday afternoon. ...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 0251 PM CDT Mon Aug 11 2025 Valid 121200Z - 131200Z Only minor adjustments were made to the D2 Fire Outlook Isolated Dry Thunderstorm area to expand into north-western Arizona in alignment with recent hi-res guidance. See previous discussion below for more information. ..Thornton.. 08/11/2025 .PREV DISCUSSION... /ISSUED 0135 AM CDT Mon Aug 11 2025/ ...Synopsis... Isolated dry thunderstorms will remain the primary fire weather concern for Tuesday across the country. Latest forecast guidance hints that a deeply-mixed, but adequately buoyant, environment will remain in place across central AZ on the northern fringe of deeper monsoonal moisture. Forcing for ascent will be fairly weak and largely driven by orographic ascent along the Mogollon Rim. However, several deterministic CAM and recent HREF guidance hints at the potential for at least a few thunderstorms. This thermodynamic environment has yielded a mixture of wet and dry thunderstorms over the past 24 hours, so a similar combination appears probable for Tuesday. Fine fuels largely remain dry across the region, and recent lightning-caused fires hint that the fuel environment should support at least some fire starts. ...Pacific Northwest... A weak mid-level trough is forecast to move across the Pacific Northwest on Tuesday. While flow aloft will be fairly modest, the zonal flow over the Cascades and northern Sierra Nevada will likely induce a downslope flow regime within an antecedent dry environment with receptive fuels. Ensemble support was too limited to warrant additional highlights, but localized elevated fire weather conditions appear possible across far northwest NV, eastern OR, and southern WA Tuesday afternoon. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0227 PM CDT Mon Aug 11 2025 Valid 131200Z - 141200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS LATE WEDNESDAY INTO WEDNESDAY NIGHT ACROSS MUCH OF CENTRAL AND EASTERN SOUTH DAKOTA AND ADJACENT PORTIONS OF THE GREAT PLAINS... ...SUMMARY... The evolution of an organized cluster of thunderstorms accompanied by strong to severe wind gusts appears possible across parts of central through eastern South Dakota by Wednesday evening. ...Discussion... Models indicate that the stronger westerlies will remain confined to the northern mid-latitudes, mostly to the north of the Canadian/U.S. border through this period. One significant embedded short wave trough shifting across Ontario through Quebec may become sheared while becoming absorbed within an increasingly confluent regime, preceded in lower latitudes by northeastward accelerating mid-level troughing offshore of the Canadian Maritimes. Upstream, another significant short wave perturbation, initially digging near the Canadian Rockies, is forecast to turn eastward across the Canadian Prairies and provide support for significant lower/mid-tropospheric cyclogenesis across southern Alberta through central/northern Saskatchewan by late Wednesday night. In lower latitudes ahead of this feature, there appears a consensus among latest model output that a much more subtle perturbation will dig east-southeast of the northern U.S. Rockies late Wednesday through Wednesday night, within weaker flow on the northern periphery of modest mid-level ridging. ...Northern Great Plains... The NAM, with support from other model output, including the latest ECMWF, depicts the evolution of a notable convective perturbation Wednesday evening into Wednesday night across the central/eastern South Dakota vicinity. This appears focused where lower/mid-tropospheric warm advection may become enhanced, near the leading edge of a plume of warm, elevated mixed layer air advecting eastward across the middle Missouri Valley, supported by a strengthening nocturnal low-level jet. Low-level moisture return to the vicinity of deepening lee surface troughing may be seasonably modest, but it still appears that sizable CAPE may develop across parts of central South Dakota by late afternoon, near the nose of a corridor of seasonably strong boundary-layer heating and deep mixing, south through east of the Black Hills. It remains unclear whether stronger convective development will initiate from late afternoon high-based thunderstorm development near/north of the Black Hills, or perhaps an initial supercell forming near a focused area of low-level convergence across central South Dakota. However, large-scale forcing for ascent probably will lead to upscale growing convection by Wednesday evening, in an environment conducive to a few strong downbursts, and a consolidating, strengthening surface cold pool with potential to produce a swath of strong to severe gusts. It is possible that severe probabilities may still need to be increased further in later outlooks for this period. ..Kerr.. 08/11/2025 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0227 PM CDT Mon Aug 11 2025 Valid 131200Z - 141200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS LATE WEDNESDAY INTO WEDNESDAY NIGHT ACROSS MUCH OF CENTRAL AND EASTERN SOUTH DAKOTA AND ADJACENT PORTIONS OF THE GREAT PLAINS... ...SUMMARY... The evolution of an organized cluster of thunderstorms accompanied by strong to severe wind gusts appears possible across parts of central through eastern South Dakota by Wednesday evening. ...Discussion... Models indicate that the stronger westerlies will remain confined to the northern mid-latitudes, mostly to the north of the Canadian/U.S. border through this period. One significant embedded short wave trough shifting across Ontario through Quebec may become sheared while becoming absorbed within an increasingly confluent regime, preceded in lower latitudes by northeastward accelerating mid-level troughing offshore of the Canadian Maritimes. Upstream, another significant short wave perturbation, initially digging near the Canadian Rockies, is forecast to turn eastward across the Canadian Prairies and provide support for significant lower/mid-tropospheric cyclogenesis across southern Alberta through central/northern Saskatchewan by late Wednesday night. In lower latitudes ahead of this feature, there appears a consensus among latest model output that a much more subtle perturbation will dig east-southeast of the northern U.S. Rockies late Wednesday through Wednesday night, within weaker flow on the northern periphery of modest mid-level ridging. ...Northern Great Plains... The NAM, with support from other model output, including the latest ECMWF, depicts the evolution of a notable convective perturbation Wednesday evening into Wednesday night across the central/eastern South Dakota vicinity. This appears focused where lower/mid-tropospheric warm advection may become enhanced, near the leading edge of a plume of warm, elevated mixed layer air advecting eastward across the middle Missouri Valley, supported by a strengthening nocturnal low-level jet. Low-level moisture return to the vicinity of deepening lee surface troughing may be seasonably modest, but it still appears that sizable CAPE may develop across parts of central South Dakota by late afternoon, near the nose of a corridor of seasonably strong boundary-layer heating and deep mixing, south through east of the Black Hills. It remains unclear whether stronger convective development will initiate from late afternoon high-based thunderstorm development near/north of the Black Hills, or perhaps an initial supercell forming near a focused area of low-level convergence across central South Dakota. However, large-scale forcing for ascent probably will lead to upscale growing convection by Wednesday evening, in an environment conducive to a few strong downbursts, and a consolidating, strengthening surface cold pool with potential to produce a swath of strong to severe gusts. It is possible that severe probabilities may still need to be increased further in later outlooks for this period. ..Kerr.. 08/11/2025 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0227 PM CDT Mon Aug 11 2025 Valid 131200Z - 141200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS LATE WEDNESDAY INTO WEDNESDAY NIGHT ACROSS MUCH OF CENTRAL AND EASTERN SOUTH DAKOTA AND ADJACENT PORTIONS OF THE GREAT PLAINS... ...SUMMARY... The evolution of an organized cluster of thunderstorms accompanied by strong to severe wind gusts appears possible across parts of central through eastern South Dakota by Wednesday evening. ...Discussion... Models indicate that the stronger westerlies will remain confined to the northern mid-latitudes, mostly to the north of the Canadian/U.S. border through this period. One significant embedded short wave trough shifting across Ontario through Quebec may become sheared while becoming absorbed within an increasingly confluent regime, preceded in lower latitudes by northeastward accelerating mid-level troughing offshore of the Canadian Maritimes. Upstream, another significant short wave perturbation, initially digging near the Canadian Rockies, is forecast to turn eastward across the Canadian Prairies and provide support for significant lower/mid-tropospheric cyclogenesis across southern Alberta through central/northern Saskatchewan by late Wednesday night. In lower latitudes ahead of this feature, there appears a consensus among latest model output that a much more subtle perturbation will dig east-southeast of the northern U.S. Rockies late Wednesday through Wednesday night, within weaker flow on the northern periphery of modest mid-level ridging. ...Northern Great Plains... The NAM, with support from other model output, including the latest ECMWF, depicts the evolution of a notable convective perturbation Wednesday evening into Wednesday night across the central/eastern South Dakota vicinity. This appears focused where lower/mid-tropospheric warm advection may become enhanced, near the leading edge of a plume of warm, elevated mixed layer air advecting eastward across the middle Missouri Valley, supported by a strengthening nocturnal low-level jet. Low-level moisture return to the vicinity of deepening lee surface troughing may be seasonably modest, but it still appears that sizable CAPE may develop across parts of central South Dakota by late afternoon, near the nose of a corridor of seasonably strong boundary-layer heating and deep mixing, south through east of the Black Hills. It remains unclear whether stronger convective development will initiate from late afternoon high-based thunderstorm development near/north of the Black Hills, or perhaps an initial supercell forming near a focused area of low-level convergence across central South Dakota. However, large-scale forcing for ascent probably will lead to upscale growing convection by Wednesday evening, in an environment conducive to a few strong downbursts, and a consolidating, strengthening surface cold pool with potential to produce a swath of strong to severe gusts. It is possible that severe probabilities may still need to be increased further in later outlooks for this period. ..Kerr.. 08/11/2025 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0227 PM CDT Mon Aug 11 2025 Valid 131200Z - 141200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS LATE WEDNESDAY INTO WEDNESDAY NIGHT ACROSS MUCH OF CENTRAL AND EASTERN SOUTH DAKOTA AND ADJACENT PORTIONS OF THE GREAT PLAINS... ...SUMMARY... The evolution of an organized cluster of thunderstorms accompanied by strong to severe wind gusts appears possible across parts of central through eastern South Dakota by Wednesday evening. ...Discussion... Models indicate that the stronger westerlies will remain confined to the northern mid-latitudes, mostly to the north of the Canadian/U.S. border through this period. One significant embedded short wave trough shifting across Ontario through Quebec may become sheared while becoming absorbed within an increasingly confluent regime, preceded in lower latitudes by northeastward accelerating mid-level troughing offshore of the Canadian Maritimes. Upstream, another significant short wave perturbation, initially digging near the Canadian Rockies, is forecast to turn eastward across the Canadian Prairies and provide support for significant lower/mid-tropospheric cyclogenesis across southern Alberta through central/northern Saskatchewan by late Wednesday night. In lower latitudes ahead of this feature, there appears a consensus among latest model output that a much more subtle perturbation will dig east-southeast of the northern U.S. Rockies late Wednesday through Wednesday night, within weaker flow on the northern periphery of modest mid-level ridging. ...Northern Great Plains... The NAM, with support from other model output, including the latest ECMWF, depicts the evolution of a notable convective perturbation Wednesday evening into Wednesday night across the central/eastern South Dakota vicinity. This appears focused where lower/mid-tropospheric warm advection may become enhanced, near the leading edge of a plume of warm, elevated mixed layer air advecting eastward across the middle Missouri Valley, supported by a strengthening nocturnal low-level jet. Low-level moisture return to the vicinity of deepening lee surface troughing may be seasonably modest, but it still appears that sizable CAPE may develop across parts of central South Dakota by late afternoon, near the nose of a corridor of seasonably strong boundary-layer heating and deep mixing, south through east of the Black Hills. It remains unclear whether stronger convective development will initiate from late afternoon high-based thunderstorm development near/north of the Black Hills, or perhaps an initial supercell forming near a focused area of low-level convergence across central South Dakota. However, large-scale forcing for ascent probably will lead to upscale growing convection by Wednesday evening, in an environment conducive to a few strong downbursts, and a consolidating, strengthening surface cold pool with potential to produce a swath of strong to severe gusts. It is possible that severe probabilities may still need to be increased further in later outlooks for this period. ..Kerr.. 08/11/2025 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0227 PM CDT Mon Aug 11 2025 Valid 131200Z - 141200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS LATE WEDNESDAY INTO WEDNESDAY NIGHT ACROSS MUCH OF CENTRAL AND EASTERN SOUTH DAKOTA AND ADJACENT PORTIONS OF THE GREAT PLAINS... ...SUMMARY... The evolution of an organized cluster of thunderstorms accompanied by strong to severe wind gusts appears possible across parts of central through eastern South Dakota by Wednesday evening. ...Discussion... Models indicate that the stronger westerlies will remain confined to the northern mid-latitudes, mostly to the north of the Canadian/U.S. border through this period. One significant embedded short wave trough shifting across Ontario through Quebec may become sheared while becoming absorbed within an increasingly confluent regime, preceded in lower latitudes by northeastward accelerating mid-level troughing offshore of the Canadian Maritimes. Upstream, another significant short wave perturbation, initially digging near the Canadian Rockies, is forecast to turn eastward across the Canadian Prairies and provide support for significant lower/mid-tropospheric cyclogenesis across southern Alberta through central/northern Saskatchewan by late Wednesday night. In lower latitudes ahead of this feature, there appears a consensus among latest model output that a much more subtle perturbation will dig east-southeast of the northern U.S. Rockies late Wednesday through Wednesday night, within weaker flow on the northern periphery of modest mid-level ridging. ...Northern Great Plains... The NAM, with support from other model output, including the latest ECMWF, depicts the evolution of a notable convective perturbation Wednesday evening into Wednesday night across the central/eastern South Dakota vicinity. This appears focused where lower/mid-tropospheric warm advection may become enhanced, near the leading edge of a plume of warm, elevated mixed layer air advecting eastward across the middle Missouri Valley, supported by a strengthening nocturnal low-level jet. Low-level moisture return to the vicinity of deepening lee surface troughing may be seasonably modest, but it still appears that sizable CAPE may develop across parts of central South Dakota by late afternoon, near the nose of a corridor of seasonably strong boundary-layer heating and deep mixing, south through east of the Black Hills. It remains unclear whether stronger convective development will initiate from late afternoon high-based thunderstorm development near/north of the Black Hills, or perhaps an initial supercell forming near a focused area of low-level convergence across central South Dakota. However, large-scale forcing for ascent probably will lead to upscale growing convection by Wednesday evening, in an environment conducive to a few strong downbursts, and a consolidating, strengthening surface cold pool with potential to produce a swath of strong to severe gusts. It is possible that severe probabilities may still need to be increased further in later outlooks for this period. ..Kerr.. 08/11/2025 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0227 PM CDT Mon Aug 11 2025 Valid 131200Z - 141200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS LATE WEDNESDAY INTO WEDNESDAY NIGHT ACROSS MUCH OF CENTRAL AND EASTERN SOUTH DAKOTA AND ADJACENT PORTIONS OF THE GREAT PLAINS... ...SUMMARY... The evolution of an organized cluster of thunderstorms accompanied by strong to severe wind gusts appears possible across parts of central through eastern South Dakota by Wednesday evening. ...Discussion... Models indicate that the stronger westerlies will remain confined to the northern mid-latitudes, mostly to the north of the Canadian/U.S. border through this period. One significant embedded short wave trough shifting across Ontario through Quebec may become sheared while becoming absorbed within an increasingly confluent regime, preceded in lower latitudes by northeastward accelerating mid-level troughing offshore of the Canadian Maritimes. Upstream, another significant short wave perturbation, initially digging near the Canadian Rockies, is forecast to turn eastward across the Canadian Prairies and provide support for significant lower/mid-tropospheric cyclogenesis across southern Alberta through central/northern Saskatchewan by late Wednesday night. In lower latitudes ahead of this feature, there appears a consensus among latest model output that a much more subtle perturbation will dig east-southeast of the northern U.S. Rockies late Wednesday through Wednesday night, within weaker flow on the northern periphery of modest mid-level ridging. ...Northern Great Plains... The NAM, with support from other model output, including the latest ECMWF, depicts the evolution of a notable convective perturbation Wednesday evening into Wednesday night across the central/eastern South Dakota vicinity. This appears focused where lower/mid-tropospheric warm advection may become enhanced, near the leading edge of a plume of warm, elevated mixed layer air advecting eastward across the middle Missouri Valley, supported by a strengthening nocturnal low-level jet. Low-level moisture return to the vicinity of deepening lee surface troughing may be seasonably modest, but it still appears that sizable CAPE may develop across parts of central South Dakota by late afternoon, near the nose of a corridor of seasonably strong boundary-layer heating and deep mixing, south through east of the Black Hills. It remains unclear whether stronger convective development will initiate from late afternoon high-based thunderstorm development near/north of the Black Hills, or perhaps an initial supercell forming near a focused area of low-level convergence across central South Dakota. However, large-scale forcing for ascent probably will lead to upscale growing convection by Wednesday evening, in an environment conducive to a few strong downbursts, and a consolidating, strengthening surface cold pool with potential to produce a swath of strong to severe gusts. It is possible that severe probabilities may still need to be increased further in later outlooks for this period. ..Kerr.. 08/11/2025 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0227 PM CDT Mon Aug 11 2025 Valid 131200Z - 141200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS LATE WEDNESDAY INTO WEDNESDAY NIGHT ACROSS MUCH OF CENTRAL AND EASTERN SOUTH DAKOTA AND ADJACENT PORTIONS OF THE GREAT PLAINS... ...SUMMARY... The evolution of an organized cluster of thunderstorms accompanied by strong to severe wind gusts appears possible across parts of central through eastern South Dakota by Wednesday evening. ...Discussion... Models indicate that the stronger westerlies will remain confined to the northern mid-latitudes, mostly to the north of the Canadian/U.S. border through this period. One significant embedded short wave trough shifting across Ontario through Quebec may become sheared while becoming absorbed within an increasingly confluent regime, preceded in lower latitudes by northeastward accelerating mid-level troughing offshore of the Canadian Maritimes. Upstream, another significant short wave perturbation, initially digging near the Canadian Rockies, is forecast to turn eastward across the Canadian Prairies and provide support for significant lower/mid-tropospheric cyclogenesis across southern Alberta through central/northern Saskatchewan by late Wednesday night. In lower latitudes ahead of this feature, there appears a consensus among latest model output that a much more subtle perturbation will dig east-southeast of the northern U.S. Rockies late Wednesday through Wednesday night, within weaker flow on the northern periphery of modest mid-level ridging. ...Northern Great Plains... The NAM, with support from other model output, including the latest ECMWF, depicts the evolution of a notable convective perturbation Wednesday evening into Wednesday night across the central/eastern South Dakota vicinity. This appears focused where lower/mid-tropospheric warm advection may become enhanced, near the leading edge of a plume of warm, elevated mixed layer air advecting eastward across the middle Missouri Valley, supported by a strengthening nocturnal low-level jet. Low-level moisture return to the vicinity of deepening lee surface troughing may be seasonably modest, but it still appears that sizable CAPE may develop across parts of central South Dakota by late afternoon, near the nose of a corridor of seasonably strong boundary-layer heating and deep mixing, south through east of the Black Hills. It remains unclear whether stronger convective development will initiate from late afternoon high-based thunderstorm development near/north of the Black Hills, or perhaps an initial supercell forming near a focused area of low-level convergence across central South Dakota. However, large-scale forcing for ascent probably will lead to upscale growing convection by Wednesday evening, in an environment conducive to a few strong downbursts, and a consolidating, strengthening surface cold pool with potential to produce a swath of strong to severe gusts. It is possible that severe probabilities may still need to be increased further in later outlooks for this period. ..Kerr.. 08/11/2025 Read more