Severe Storms

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0230 AM CDT Mon Sep 02 2024 Valid 041200Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTH-CENTRAL U.S. AND INTO THE ROCKIES... ...SUMMARY... Risk for isolated strong to severe storms -- capable of producing gusty/locally damaging winds -- will be possible from parts of Montana/Wyoming/Colorado into the northern Plains Wednesday/Wednesday night. Marginal hail with stronger storms may also occur across the northern Plains region. ...Synopsis... The main upper feature of interest with respect to convective/local severe risk will be a short-wave trough initially situated from the northern Intermountain region to the Great Basin. As this feature advances eastward toward -- and eventually into -- the northern and central Plains, it is expected to gradually phase with larger-scale trough digging southeastward into the Canadian Prairie. This will result in slow amplification of the upper pattern over Canada and the adjacent northern half of the U.S. through Thursday morning. At the surface, a baroclinic zone is forecast to linger in the vicinity of the Gulf Coast/northern Gulf of Mexico, at the southern fringe of a drier Continental airmass represented by a large area of high pressure over the eastern and into the central states. Meanwhile, a second cold front -- ahead of the evolving northern U.S. upper trough -- will shift eastward across the northern Plains and southward into the central Plains through the period. By Thursday morning, the front should extend from Minnesota southwestward to the Far West Texas vicinity. ...Northern Plains into parts of Montana/Wyoming/Colorado... Diurnal heating in the wake of the advancing cold front/beneath the upper trough will result in modest destabilization across portions of Montana/Wyoming/Colorado during the afternoon -- resulting in development of isolated thunderstorms. With a belt of moderate mid-level west-southwesterlies supporting locally stronger updrafts, and a deep mixed layer suggesting some evaporative enhancement potential in the sub-cloud layer, a few instances of strong/severe outflow winds are expected. Farther east, destabilization near/ahead of the advancing from should support isolated storm by late afternoon, and continuing into the evening hours. With shear becoming sufficient for organized updrafts, a few stronger storms during the afternoon and evening should prove capable of producing strong/gusty winds and marginal hail, before nocturnally weakening. ..Goss.. 09/02/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0230 AM CDT Mon Sep 02 2024 Valid 041200Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTH-CENTRAL U.S. AND INTO THE ROCKIES... ...SUMMARY... Risk for isolated strong to severe storms -- capable of producing gusty/locally damaging winds -- will be possible from parts of Montana/Wyoming/Colorado into the northern Plains Wednesday/Wednesday night. Marginal hail with stronger storms may also occur across the northern Plains region. ...Synopsis... The main upper feature of interest with respect to convective/local severe risk will be a short-wave trough initially situated from the northern Intermountain region to the Great Basin. As this feature advances eastward toward -- and eventually into -- the northern and central Plains, it is expected to gradually phase with larger-scale trough digging southeastward into the Canadian Prairie. This will result in slow amplification of the upper pattern over Canada and the adjacent northern half of the U.S. through Thursday morning. At the surface, a baroclinic zone is forecast to linger in the vicinity of the Gulf Coast/northern Gulf of Mexico, at the southern fringe of a drier Continental airmass represented by a large area of high pressure over the eastern and into the central states. Meanwhile, a second cold front -- ahead of the evolving northern U.S. upper trough -- will shift eastward across the northern Plains and southward into the central Plains through the period. By Thursday morning, the front should extend from Minnesota southwestward to the Far West Texas vicinity. ...Northern Plains into parts of Montana/Wyoming/Colorado... Diurnal heating in the wake of the advancing cold front/beneath the upper trough will result in modest destabilization across portions of Montana/Wyoming/Colorado during the afternoon -- resulting in development of isolated thunderstorms. With a belt of moderate mid-level west-southwesterlies supporting locally stronger updrafts, and a deep mixed layer suggesting some evaporative enhancement potential in the sub-cloud layer, a few instances of strong/severe outflow winds are expected. Farther east, destabilization near/ahead of the advancing from should support isolated storm by late afternoon, and continuing into the evening hours. With shear becoming sufficient for organized updrafts, a few stronger storms during the afternoon and evening should prove capable of producing strong/gusty winds and marginal hail, before nocturnally weakening. ..Goss.. 09/02/2024 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0218 AM CDT Mon Sep 02 2024 Valid 031200Z - 041200Z ...Synopsis... Fire weather concerns will continue into Tuesday as an upper wave (currently moving onshore along the northern CA coast) translates east across the northern Rockies. However, fire weather conditions are not expected to be as intense or widespread as compared to Monday across on either side of the continental divide. ...Nevada into Idaho... Portions of northeast NV and central ID are forecast to remain within the dry slot of the maturing upper-level low. This will maintain clear skies/warm conditions across the region, but will also support broad scale subsidence/drying and windy conditions across the region. Regional orographic influences - namely the Snake River Plain in eastern ID as well as the Independence and Ruby mountains of northeast NV, will augment the dry/windy conditions and should support several hours of elevated fire weather conditions. Isolated to scattered thunderstorms are also anticipated across northern ID, MT, and WY by late afternoon as the low shifts east. While a few dry thunderstorms are possible based on forecast thermal profiles, recent ensemble guidance shows a stronger signal for wetting rainfall compared to Monday, limiting confidence in the dry-lightning threat. ...Central/Northern Plains... A lee trough is expected to become established over the next 24 hours, but will see more substantial deepening through Tuesday afternoon amid increasing synoptic-scale ascent ahead of the approaching upper wave. This will result in not only strengthening westerly downslope flow across eastern WY, but will also bolster pressure gradient winds across central NE into SD. Recent ensemble guidance shows reasonably high confidence in maintaining at least a few hours of elevated fire weather conditions for both regions with 15-20 mph winds and RH reductions into the teens and low 20s. Persistent southerly flow overnight Monday into Tuesday will support some degree of moisture return into the Plains, which is expected to limit the spatial coverage of elevated fire weather conditions. That said, guidance typically struggles to accurately capture boundary-layer mixing/RH reductions in such return flow regimes, and fire weather conditions may be more widespread across NE/SD than currently depicted. ..Moore.. 09/02/2024 ...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 0218 AM CDT Mon Sep 02 2024 Valid 031200Z - 041200Z ...Synopsis... Fire weather concerns will continue into Tuesday as an upper wave (currently moving onshore along the northern CA coast) translates east across the northern Rockies. However, fire weather conditions are not expected to be as intense or widespread as compared to Monday across on either side of the continental divide. ...Nevada into Idaho... Portions of northeast NV and central ID are forecast to remain within the dry slot of the maturing upper-level low. This will maintain clear skies/warm conditions across the region, but will also support broad scale subsidence/drying and windy conditions across the region. Regional orographic influences - namely the Snake River Plain in eastern ID as well as the Independence and Ruby mountains of northeast NV, will augment the dry/windy conditions and should support several hours of elevated fire weather conditions. Isolated to scattered thunderstorms are also anticipated across northern ID, MT, and WY by late afternoon as the low shifts east. While a few dry thunderstorms are possible based on forecast thermal profiles, recent ensemble guidance shows a stronger signal for wetting rainfall compared to Monday, limiting confidence in the dry-lightning threat. ...Central/Northern Plains... A lee trough is expected to become established over the next 24 hours, but will see more substantial deepening through Tuesday afternoon amid increasing synoptic-scale ascent ahead of the approaching upper wave. This will result in not only strengthening westerly downslope flow across eastern WY, but will also bolster pressure gradient winds across central NE into SD. Recent ensemble guidance shows reasonably high confidence in maintaining at least a few hours of elevated fire weather conditions for both regions with 15-20 mph winds and RH reductions into the teens and low 20s. Persistent southerly flow overnight Monday into Tuesday will support some degree of moisture return into the Plains, which is expected to limit the spatial coverage of elevated fire weather conditions. That said, guidance typically struggles to accurately capture boundary-layer mixing/RH reductions in such return flow regimes, and fire weather conditions may be more widespread across NE/SD than currently depicted. ..Moore.. 09/02/2024 ...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 0218 AM CDT Mon Sep 02 2024 Valid 031200Z - 041200Z ...Synopsis... Fire weather concerns will continue into Tuesday as an upper wave (currently moving onshore along the northern CA coast) translates east across the northern Rockies. However, fire weather conditions are not expected to be as intense or widespread as compared to Monday across on either side of the continental divide. ...Nevada into Idaho... Portions of northeast NV and central ID are forecast to remain within the dry slot of the maturing upper-level low. This will maintain clear skies/warm conditions across the region, but will also support broad scale subsidence/drying and windy conditions across the region. Regional orographic influences - namely the Snake River Plain in eastern ID as well as the Independence and Ruby mountains of northeast NV, will augment the dry/windy conditions and should support several hours of elevated fire weather conditions. Isolated to scattered thunderstorms are also anticipated across northern ID, MT, and WY by late afternoon as the low shifts east. While a few dry thunderstorms are possible based on forecast thermal profiles, recent ensemble guidance shows a stronger signal for wetting rainfall compared to Monday, limiting confidence in the dry-lightning threat. ...Central/Northern Plains... A lee trough is expected to become established over the next 24 hours, but will see more substantial deepening through Tuesday afternoon amid increasing synoptic-scale ascent ahead of the approaching upper wave. This will result in not only strengthening westerly downslope flow across eastern WY, but will also bolster pressure gradient winds across central NE into SD. Recent ensemble guidance shows reasonably high confidence in maintaining at least a few hours of elevated fire weather conditions for both regions with 15-20 mph winds and RH reductions into the teens and low 20s. Persistent southerly flow overnight Monday into Tuesday will support some degree of moisture return into the Plains, which is expected to limit the spatial coverage of elevated fire weather conditions. That said, guidance typically struggles to accurately capture boundary-layer mixing/RH reductions in such return flow regimes, and fire weather conditions may be more widespread across NE/SD than currently depicted. ..Moore.. 09/02/2024 ...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 0218 AM CDT Mon Sep 02 2024 Valid 031200Z - 041200Z ...Synopsis... Fire weather concerns will continue into Tuesday as an upper wave (currently moving onshore along the northern CA coast) translates east across the northern Rockies. However, fire weather conditions are not expected to be as intense or widespread as compared to Monday across on either side of the continental divide. ...Nevada into Idaho... Portions of northeast NV and central ID are forecast to remain within the dry slot of the maturing upper-level low. This will maintain clear skies/warm conditions across the region, but will also support broad scale subsidence/drying and windy conditions across the region. Regional orographic influences - namely the Snake River Plain in eastern ID as well as the Independence and Ruby mountains of northeast NV, will augment the dry/windy conditions and should support several hours of elevated fire weather conditions. Isolated to scattered thunderstorms are also anticipated across northern ID, MT, and WY by late afternoon as the low shifts east. While a few dry thunderstorms are possible based on forecast thermal profiles, recent ensemble guidance shows a stronger signal for wetting rainfall compared to Monday, limiting confidence in the dry-lightning threat. ...Central/Northern Plains... A lee trough is expected to become established over the next 24 hours, but will see more substantial deepening through Tuesday afternoon amid increasing synoptic-scale ascent ahead of the approaching upper wave. This will result in not only strengthening westerly downslope flow across eastern WY, but will also bolster pressure gradient winds across central NE into SD. Recent ensemble guidance shows reasonably high confidence in maintaining at least a few hours of elevated fire weather conditions for both regions with 15-20 mph winds and RH reductions into the teens and low 20s. Persistent southerly flow overnight Monday into Tuesday will support some degree of moisture return into the Plains, which is expected to limit the spatial coverage of elevated fire weather conditions. That said, guidance typically struggles to accurately capture boundary-layer mixing/RH reductions in such return flow regimes, and fire weather conditions may be more widespread across NE/SD than currently depicted. ..Moore.. 09/02/2024 ...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 0218 AM CDT Mon Sep 02 2024 Valid 031200Z - 041200Z ...Synopsis... Fire weather concerns will continue into Tuesday as an upper wave (currently moving onshore along the northern CA coast) translates east across the northern Rockies. However, fire weather conditions are not expected to be as intense or widespread as compared to Monday across on either side of the continental divide. ...Nevada into Idaho... Portions of northeast NV and central ID are forecast to remain within the dry slot of the maturing upper-level low. This will maintain clear skies/warm conditions across the region, but will also support broad scale subsidence/drying and windy conditions across the region. Regional orographic influences - namely the Snake River Plain in eastern ID as well as the Independence and Ruby mountains of northeast NV, will augment the dry/windy conditions and should support several hours of elevated fire weather conditions. Isolated to scattered thunderstorms are also anticipated across northern ID, MT, and WY by late afternoon as the low shifts east. While a few dry thunderstorms are possible based on forecast thermal profiles, recent ensemble guidance shows a stronger signal for wetting rainfall compared to Monday, limiting confidence in the dry-lightning threat. ...Central/Northern Plains... A lee trough is expected to become established over the next 24 hours, but will see more substantial deepening through Tuesday afternoon amid increasing synoptic-scale ascent ahead of the approaching upper wave. This will result in not only strengthening westerly downslope flow across eastern WY, but will also bolster pressure gradient winds across central NE into SD. Recent ensemble guidance shows reasonably high confidence in maintaining at least a few hours of elevated fire weather conditions for both regions with 15-20 mph winds and RH reductions into the teens and low 20s. Persistent southerly flow overnight Monday into Tuesday will support some degree of moisture return into the Plains, which is expected to limit the spatial coverage of elevated fire weather conditions. That said, guidance typically struggles to accurately capture boundary-layer mixing/RH reductions in such return flow regimes, and fire weather conditions may be more widespread across NE/SD than currently depicted. ..Moore.. 09/02/2024 ...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 0218 AM CDT Mon Sep 02 2024 Valid 031200Z - 041200Z ...Synopsis... Fire weather concerns will continue into Tuesday as an upper wave (currently moving onshore along the northern CA coast) translates east across the northern Rockies. However, fire weather conditions are not expected to be as intense or widespread as compared to Monday across on either side of the continental divide. ...Nevada into Idaho... Portions of northeast NV and central ID are forecast to remain within the dry slot of the maturing upper-level low. This will maintain clear skies/warm conditions across the region, but will also support broad scale subsidence/drying and windy conditions across the region. Regional orographic influences - namely the Snake River Plain in eastern ID as well as the Independence and Ruby mountains of northeast NV, will augment the dry/windy conditions and should support several hours of elevated fire weather conditions. Isolated to scattered thunderstorms are also anticipated across northern ID, MT, and WY by late afternoon as the low shifts east. While a few dry thunderstorms are possible based on forecast thermal profiles, recent ensemble guidance shows a stronger signal for wetting rainfall compared to Monday, limiting confidence in the dry-lightning threat. ...Central/Northern Plains... A lee trough is expected to become established over the next 24 hours, but will see more substantial deepening through Tuesday afternoon amid increasing synoptic-scale ascent ahead of the approaching upper wave. This will result in not only strengthening westerly downslope flow across eastern WY, but will also bolster pressure gradient winds across central NE into SD. Recent ensemble guidance shows reasonably high confidence in maintaining at least a few hours of elevated fire weather conditions for both regions with 15-20 mph winds and RH reductions into the teens and low 20s. Persistent southerly flow overnight Monday into Tuesday will support some degree of moisture return into the Plains, which is expected to limit the spatial coverage of elevated fire weather conditions. That said, guidance typically struggles to accurately capture boundary-layer mixing/RH reductions in such return flow regimes, and fire weather conditions may be more widespread across NE/SD than currently depicted. ..Moore.. 09/02/2024 ...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 0150 AM CDT Mon Sep 02 2024 Valid 021200Z - 031200Z ...CRITICAL FIRE WEATHER AREA FOR SOUTHERN OREGON INTO FAR NORTHEAST CALIFORNIA AND FAR NORTHWEST NEVADA... ...CRITICAL FIRE WEATHER AREA FOR SOUTHEAST OREGON INTO SOUTHWEST IDAHO...NORTHEAST NEVADA...AND FAR NORTHWEST UTAH... ...CRITICAL FIRE WEATHER AREA FOR NORTHWEST NEBRASKA INTO WESTERN SOUTH DAKOTA... ...Synopsis... An active fire weather day is anticipated across the High Plains and Pacific Northwest/northern Great Basin. Fire weather concerns across the West will be associated with a progressive upper wave currently moving onshore along the northern CA coast, which is forecast to migrate into the interior Pacific Northwest over the next 24 hours. As this occurs, strengthening low-level winds will support dry/windy conditions, and lift ahead of the wave will promote isolated to scattered thunderstorms. To the east, flow across the northern to central Rockies is forecast to strengthen slightly within the apex of an upper ridge. This will result in modest surface pressure falls along the High Plains, which when juxtaposed with a building surface high over the Midwest will yield strong southerly winds and dry conditions. Fuels across both regions remain very dry (ERCs at or above the 90th percentile) after multiple days of dry conditions, which will support the fire weather concerns. ...Pacific Northwest/Great Basin... Regional VWPs along the West Coast are beginning to observe the influence of the approaching wave with winds in the lowest few kilometers slowly strengthening since 00 UTC. Further intensification of the low-level wind field is anticipated, which will strengthen downslope flow off the central to northern Sierra Nevada. Dry conditions are already in place and will be maintained within the augmented downslope regime. Latest ensemble guidance continues to show a strong signal for afternoon RH values to fall into the teens with 15-25 mph winds. The strongest winds (and highest probability for sustained critical conditions) are expected from northeast CA into southern OR and far northwest NV as the mid-level jet max passes overhead around peak heating. Over the past several days, a plume of monsoonal moisture has been tracked from southern AZ into northern NV and central to eastern OR. The 00 UTC MFR sounding sampled this air mass well, which is characterized by sufficient mid-level moisture to support weak convection, but a very dry boundary layer favorable for dry thunderstorms. Over the past two days, thunderstorms within this air mass across the Great Basin have been predominantly dry, and are expected to mainly be dry once again today for much of the region (one exception is from the Blue Mountains in northeast OR to the Salmon River Mountains in central ID where orographic ascent should support more prolonged convection with a higher probability for wetting rainfall). Stronger synoptic-scale forcing for ascent should result in greater thunderstorm coverage compared to previous days, warranting a scattered dry thunderstorm risk area from eastern OR into ID, northeast NV, and far northwest UT where latest CAM guidance shows the best convective signal. ...High Plains... A recent frontal intrusion into the Plains/Midwest has shunted seasonally rich moisture southward into the southern Plains. A strong surface high in the wake of the front will shift east through the day concurrent with the deepening of a weak lee trough. A dry return flow regime will become established through the day as winds become more southerly. Latest deterministic and ensemble solutions show a fairly strong signal for 20-25 mph winds (gusting to 35 mph) across western NE into western SD with RH values falling into the low 20s to teens. Consequently, confidence in sustained critical conditions over an appreciable area has increased enough to warrant introducing a Critical risk area. ..Moore.. 09/02/2024 ...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 0150 AM CDT Mon Sep 02 2024 Valid 021200Z - 031200Z ...CRITICAL FIRE WEATHER AREA FOR SOUTHERN OREGON INTO FAR NORTHEAST CALIFORNIA AND FAR NORTHWEST NEVADA... ...CRITICAL FIRE WEATHER AREA FOR SOUTHEAST OREGON INTO SOUTHWEST IDAHO...NORTHEAST NEVADA...AND FAR NORTHWEST UTAH... ...CRITICAL FIRE WEATHER AREA FOR NORTHWEST NEBRASKA INTO WESTERN SOUTH DAKOTA... ...Synopsis... An active fire weather day is anticipated across the High Plains and Pacific Northwest/northern Great Basin. Fire weather concerns across the West will be associated with a progressive upper wave currently moving onshore along the northern CA coast, which is forecast to migrate into the interior Pacific Northwest over the next 24 hours. As this occurs, strengthening low-level winds will support dry/windy conditions, and lift ahead of the wave will promote isolated to scattered thunderstorms. To the east, flow across the northern to central Rockies is forecast to strengthen slightly within the apex of an upper ridge. This will result in modest surface pressure falls along the High Plains, which when juxtaposed with a building surface high over the Midwest will yield strong southerly winds and dry conditions. Fuels across both regions remain very dry (ERCs at or above the 90th percentile) after multiple days of dry conditions, which will support the fire weather concerns. ...Pacific Northwest/Great Basin... Regional VWPs along the West Coast are beginning to observe the influence of the approaching wave with winds in the lowest few kilometers slowly strengthening since 00 UTC. Further intensification of the low-level wind field is anticipated, which will strengthen downslope flow off the central to northern Sierra Nevada. Dry conditions are already in place and will be maintained within the augmented downslope regime. Latest ensemble guidance continues to show a strong signal for afternoon RH values to fall into the teens with 15-25 mph winds. The strongest winds (and highest probability for sustained critical conditions) are expected from northeast CA into southern OR and far northwest NV as the mid-level jet max passes overhead around peak heating. Over the past several days, a plume of monsoonal moisture has been tracked from southern AZ into northern NV and central to eastern OR. The 00 UTC MFR sounding sampled this air mass well, which is characterized by sufficient mid-level moisture to support weak convection, but a very dry boundary layer favorable for dry thunderstorms. Over the past two days, thunderstorms within this air mass across the Great Basin have been predominantly dry, and are expected to mainly be dry once again today for much of the region (one exception is from the Blue Mountains in northeast OR to the Salmon River Mountains in central ID where orographic ascent should support more prolonged convection with a higher probability for wetting rainfall). Stronger synoptic-scale forcing for ascent should result in greater thunderstorm coverage compared to previous days, warranting a scattered dry thunderstorm risk area from eastern OR into ID, northeast NV, and far northwest UT where latest CAM guidance shows the best convective signal. ...High Plains... A recent frontal intrusion into the Plains/Midwest has shunted seasonally rich moisture southward into the southern Plains. A strong surface high in the wake of the front will shift east through the day concurrent with the deepening of a weak lee trough. A dry return flow regime will become established through the day as winds become more southerly. Latest deterministic and ensemble solutions show a fairly strong signal for 20-25 mph winds (gusting to 35 mph) across western NE into western SD with RH values falling into the low 20s to teens. Consequently, confidence in sustained critical conditions over an appreciable area has increased enough to warrant introducing a Critical risk area. ..Moore.. 09/02/2024 ...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 0150 AM CDT Mon Sep 02 2024 Valid 021200Z - 031200Z ...CRITICAL FIRE WEATHER AREA FOR SOUTHERN OREGON INTO FAR NORTHEAST CALIFORNIA AND FAR NORTHWEST NEVADA... ...CRITICAL FIRE WEATHER AREA FOR SOUTHEAST OREGON INTO SOUTHWEST IDAHO...NORTHEAST NEVADA...AND FAR NORTHWEST UTAH... ...CRITICAL FIRE WEATHER AREA FOR NORTHWEST NEBRASKA INTO WESTERN SOUTH DAKOTA... ...Synopsis... An active fire weather day is anticipated across the High Plains and Pacific Northwest/northern Great Basin. Fire weather concerns across the West will be associated with a progressive upper wave currently moving onshore along the northern CA coast, which is forecast to migrate into the interior Pacific Northwest over the next 24 hours. As this occurs, strengthening low-level winds will support dry/windy conditions, and lift ahead of the wave will promote isolated to scattered thunderstorms. To the east, flow across the northern to central Rockies is forecast to strengthen slightly within the apex of an upper ridge. This will result in modest surface pressure falls along the High Plains, which when juxtaposed with a building surface high over the Midwest will yield strong southerly winds and dry conditions. Fuels across both regions remain very dry (ERCs at or above the 90th percentile) after multiple days of dry conditions, which will support the fire weather concerns. ...Pacific Northwest/Great Basin... Regional VWPs along the West Coast are beginning to observe the influence of the approaching wave with winds in the lowest few kilometers slowly strengthening since 00 UTC. Further intensification of the low-level wind field is anticipated, which will strengthen downslope flow off the central to northern Sierra Nevada. Dry conditions are already in place and will be maintained within the augmented downslope regime. Latest ensemble guidance continues to show a strong signal for afternoon RH values to fall into the teens with 15-25 mph winds. The strongest winds (and highest probability for sustained critical conditions) are expected from northeast CA into southern OR and far northwest NV as the mid-level jet max passes overhead around peak heating. Over the past several days, a plume of monsoonal moisture has been tracked from southern AZ into northern NV and central to eastern OR. The 00 UTC MFR sounding sampled this air mass well, which is characterized by sufficient mid-level moisture to support weak convection, but a very dry boundary layer favorable for dry thunderstorms. Over the past two days, thunderstorms within this air mass across the Great Basin have been predominantly dry, and are expected to mainly be dry once again today for much of the region (one exception is from the Blue Mountains in northeast OR to the Salmon River Mountains in central ID where orographic ascent should support more prolonged convection with a higher probability for wetting rainfall). Stronger synoptic-scale forcing for ascent should result in greater thunderstorm coverage compared to previous days, warranting a scattered dry thunderstorm risk area from eastern OR into ID, northeast NV, and far northwest UT where latest CAM guidance shows the best convective signal. ...High Plains... A recent frontal intrusion into the Plains/Midwest has shunted seasonally rich moisture southward into the southern Plains. A strong surface high in the wake of the front will shift east through the day concurrent with the deepening of a weak lee trough. A dry return flow regime will become established through the day as winds become more southerly. Latest deterministic and ensemble solutions show a fairly strong signal for 20-25 mph winds (gusting to 35 mph) across western NE into western SD with RH values falling into the low 20s to teens. Consequently, confidence in sustained critical conditions over an appreciable area has increased enough to warrant introducing a Critical risk area. ..Moore.. 09/02/2024 ...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 0150 AM CDT Mon Sep 02 2024 Valid 021200Z - 031200Z ...CRITICAL FIRE WEATHER AREA FOR SOUTHERN OREGON INTO FAR NORTHEAST CALIFORNIA AND FAR NORTHWEST NEVADA... ...CRITICAL FIRE WEATHER AREA FOR SOUTHEAST OREGON INTO SOUTHWEST IDAHO...NORTHEAST NEVADA...AND FAR NORTHWEST UTAH... ...CRITICAL FIRE WEATHER AREA FOR NORTHWEST NEBRASKA INTO WESTERN SOUTH DAKOTA... ...Synopsis... An active fire weather day is anticipated across the High Plains and Pacific Northwest/northern Great Basin. Fire weather concerns across the West will be associated with a progressive upper wave currently moving onshore along the northern CA coast, which is forecast to migrate into the interior Pacific Northwest over the next 24 hours. As this occurs, strengthening low-level winds will support dry/windy conditions, and lift ahead of the wave will promote isolated to scattered thunderstorms. To the east, flow across the northern to central Rockies is forecast to strengthen slightly within the apex of an upper ridge. This will result in modest surface pressure falls along the High Plains, which when juxtaposed with a building surface high over the Midwest will yield strong southerly winds and dry conditions. Fuels across both regions remain very dry (ERCs at or above the 90th percentile) after multiple days of dry conditions, which will support the fire weather concerns. ...Pacific Northwest/Great Basin... Regional VWPs along the West Coast are beginning to observe the influence of the approaching wave with winds in the lowest few kilometers slowly strengthening since 00 UTC. Further intensification of the low-level wind field is anticipated, which will strengthen downslope flow off the central to northern Sierra Nevada. Dry conditions are already in place and will be maintained within the augmented downslope regime. Latest ensemble guidance continues to show a strong signal for afternoon RH values to fall into the teens with 15-25 mph winds. The strongest winds (and highest probability for sustained critical conditions) are expected from northeast CA into southern OR and far northwest NV as the mid-level jet max passes overhead around peak heating. Over the past several days, a plume of monsoonal moisture has been tracked from southern AZ into northern NV and central to eastern OR. The 00 UTC MFR sounding sampled this air mass well, which is characterized by sufficient mid-level moisture to support weak convection, but a very dry boundary layer favorable for dry thunderstorms. Over the past two days, thunderstorms within this air mass across the Great Basin have been predominantly dry, and are expected to mainly be dry once again today for much of the region (one exception is from the Blue Mountains in northeast OR to the Salmon River Mountains in central ID where orographic ascent should support more prolonged convection with a higher probability for wetting rainfall). Stronger synoptic-scale forcing for ascent should result in greater thunderstorm coverage compared to previous days, warranting a scattered dry thunderstorm risk area from eastern OR into ID, northeast NV, and far northwest UT where latest CAM guidance shows the best convective signal. ...High Plains... A recent frontal intrusion into the Plains/Midwest has shunted seasonally rich moisture southward into the southern Plains. A strong surface high in the wake of the front will shift east through the day concurrent with the deepening of a weak lee trough. A dry return flow regime will become established through the day as winds become more southerly. Latest deterministic and ensemble solutions show a fairly strong signal for 20-25 mph winds (gusting to 35 mph) across western NE into western SD with RH values falling into the low 20s to teens. Consequently, confidence in sustained critical conditions over an appreciable area has increased enough to warrant introducing a Critical risk area. ..Moore.. 09/02/2024 ...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 0150 AM CDT Mon Sep 02 2024 Valid 021200Z - 031200Z ...CRITICAL FIRE WEATHER AREA FOR SOUTHERN OREGON INTO FAR NORTHEAST CALIFORNIA AND FAR NORTHWEST NEVADA... ...CRITICAL FIRE WEATHER AREA FOR SOUTHEAST OREGON INTO SOUTHWEST IDAHO...NORTHEAST NEVADA...AND FAR NORTHWEST UTAH... ...CRITICAL FIRE WEATHER AREA FOR NORTHWEST NEBRASKA INTO WESTERN SOUTH DAKOTA... ...Synopsis... An active fire weather day is anticipated across the High Plains and Pacific Northwest/northern Great Basin. Fire weather concerns across the West will be associated with a progressive upper wave currently moving onshore along the northern CA coast, which is forecast to migrate into the interior Pacific Northwest over the next 24 hours. As this occurs, strengthening low-level winds will support dry/windy conditions, and lift ahead of the wave will promote isolated to scattered thunderstorms. To the east, flow across the northern to central Rockies is forecast to strengthen slightly within the apex of an upper ridge. This will result in modest surface pressure falls along the High Plains, which when juxtaposed with a building surface high over the Midwest will yield strong southerly winds and dry conditions. Fuels across both regions remain very dry (ERCs at or above the 90th percentile) after multiple days of dry conditions, which will support the fire weather concerns. ...Pacific Northwest/Great Basin... Regional VWPs along the West Coast are beginning to observe the influence of the approaching wave with winds in the lowest few kilometers slowly strengthening since 00 UTC. Further intensification of the low-level wind field is anticipated, which will strengthen downslope flow off the central to northern Sierra Nevada. Dry conditions are already in place and will be maintained within the augmented downslope regime. Latest ensemble guidance continues to show a strong signal for afternoon RH values to fall into the teens with 15-25 mph winds. The strongest winds (and highest probability for sustained critical conditions) are expected from northeast CA into southern OR and far northwest NV as the mid-level jet max passes overhead around peak heating. Over the past several days, a plume of monsoonal moisture has been tracked from southern AZ into northern NV and central to eastern OR. The 00 UTC MFR sounding sampled this air mass well, which is characterized by sufficient mid-level moisture to support weak convection, but a very dry boundary layer favorable for dry thunderstorms. Over the past two days, thunderstorms within this air mass across the Great Basin have been predominantly dry, and are expected to mainly be dry once again today for much of the region (one exception is from the Blue Mountains in northeast OR to the Salmon River Mountains in central ID where orographic ascent should support more prolonged convection with a higher probability for wetting rainfall). Stronger synoptic-scale forcing for ascent should result in greater thunderstorm coverage compared to previous days, warranting a scattered dry thunderstorm risk area from eastern OR into ID, northeast NV, and far northwest UT where latest CAM guidance shows the best convective signal. ...High Plains... A recent frontal intrusion into the Plains/Midwest has shunted seasonally rich moisture southward into the southern Plains. A strong surface high in the wake of the front will shift east through the day concurrent with the deepening of a weak lee trough. A dry return flow regime will become established through the day as winds become more southerly. Latest deterministic and ensemble solutions show a fairly strong signal for 20-25 mph winds (gusting to 35 mph) across western NE into western SD with RH values falling into the low 20s to teens. Consequently, confidence in sustained critical conditions over an appreciable area has increased enough to warrant introducing a Critical risk area. ..Moore.. 09/02/2024 ...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 0150 AM CDT Mon Sep 02 2024 Valid 021200Z - 031200Z ...CRITICAL FIRE WEATHER AREA FOR SOUTHERN OREGON INTO FAR NORTHEAST CALIFORNIA AND FAR NORTHWEST NEVADA... ...CRITICAL FIRE WEATHER AREA FOR SOUTHEAST OREGON INTO SOUTHWEST IDAHO...NORTHEAST NEVADA...AND FAR NORTHWEST UTAH... ...CRITICAL FIRE WEATHER AREA FOR NORTHWEST NEBRASKA INTO WESTERN SOUTH DAKOTA... ...Synopsis... An active fire weather day is anticipated across the High Plains and Pacific Northwest/northern Great Basin. Fire weather concerns across the West will be associated with a progressive upper wave currently moving onshore along the northern CA coast, which is forecast to migrate into the interior Pacific Northwest over the next 24 hours. As this occurs, strengthening low-level winds will support dry/windy conditions, and lift ahead of the wave will promote isolated to scattered thunderstorms. To the east, flow across the northern to central Rockies is forecast to strengthen slightly within the apex of an upper ridge. This will result in modest surface pressure falls along the High Plains, which when juxtaposed with a building surface high over the Midwest will yield strong southerly winds and dry conditions. Fuels across both regions remain very dry (ERCs at or above the 90th percentile) after multiple days of dry conditions, which will support the fire weather concerns. ...Pacific Northwest/Great Basin... Regional VWPs along the West Coast are beginning to observe the influence of the approaching wave with winds in the lowest few kilometers slowly strengthening since 00 UTC. Further intensification of the low-level wind field is anticipated, which will strengthen downslope flow off the central to northern Sierra Nevada. Dry conditions are already in place and will be maintained within the augmented downslope regime. Latest ensemble guidance continues to show a strong signal for afternoon RH values to fall into the teens with 15-25 mph winds. The strongest winds (and highest probability for sustained critical conditions) are expected from northeast CA into southern OR and far northwest NV as the mid-level jet max passes overhead around peak heating. Over the past several days, a plume of monsoonal moisture has been tracked from southern AZ into northern NV and central to eastern OR. The 00 UTC MFR sounding sampled this air mass well, which is characterized by sufficient mid-level moisture to support weak convection, but a very dry boundary layer favorable for dry thunderstorms. Over the past two days, thunderstorms within this air mass across the Great Basin have been predominantly dry, and are expected to mainly be dry once again today for much of the region (one exception is from the Blue Mountains in northeast OR to the Salmon River Mountains in central ID where orographic ascent should support more prolonged convection with a higher probability for wetting rainfall). Stronger synoptic-scale forcing for ascent should result in greater thunderstorm coverage compared to previous days, warranting a scattered dry thunderstorm risk area from eastern OR into ID, northeast NV, and far northwest UT where latest CAM guidance shows the best convective signal. ...High Plains... A recent frontal intrusion into the Plains/Midwest has shunted seasonally rich moisture southward into the southern Plains. A strong surface high in the wake of the front will shift east through the day concurrent with the deepening of a weak lee trough. A dry return flow regime will become established through the day as winds become more southerly. Latest deterministic and ensemble solutions show a fairly strong signal for 20-25 mph winds (gusting to 35 mph) across western NE into western SD with RH values falling into the low 20s to teens. Consequently, confidence in sustained critical conditions over an appreciable area has increased enough to warrant introducing a Critical risk area. ..Moore.. 09/02/2024 ...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 0101 AM CDT Mon Sep 02 2024 Valid 031200Z - 041200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN INTERMOUNTAIN REGION AND GREAT BASIN... ...SUMMARY... Scattered strong/a few severe storms capable of producing damaging wind gusts, and possibly marginal hail, are expected from the northern Intermountain region eastward into the northern High Plains, and southward into Utah. ...Synopsis... As a large-scale upper trough continues to vacate the northeastern U.S. Tuesday, a second/short-wave trough initially situated over the Pacific Northwest will advance eastward across the northern Intermountain region/Great Basin. At the surface, a cold front will shift eastward across the northwestern quarter of the country, in conjunction with the advancing upper trough, while westerly flow aloft will maintain a High-Plains lee trough. Meanwhile, a remnant baroclinic zone will linger from the southern Atlantic coastal area westward across the Gulf Coast/northern Gulf of Mexico through the period, as a large area of high pressure prevails north of the front, across the central and eastern U.S., through the period. ...Montana to the western Dakotas, and southward to northwestern Colorado and Utah... As the upper system advances eastward across Idaho/western Montana and the Great Basin during the afternoon, daytime heating/mixing will eventually result in 500 to 1000 J/kg mixed-layer CAPE atop a deep/dry boundary layer. This will support development of scattered thunderstorms from western Montana/eastern Idaho southward across Utah and adjacent portions of eastern Nevada. The strongest storms are expected to evolve from southwestern Montana south to northern Utah, where CAPE should be maximized ahead of the trough, and a belt of 30 to 40 kt west-southwesterly mid-level flow on the southeastern periphery of the upper trough should reside. Here, a couple of the strongest -- potentially rotating -- storms will be capable of producing both strong/severe outflow winds and possibly marginal hail. Surrounding this area, where instability and/or shear should remain a bit weaker, the primary risk will be isolated strong wind gusts. Through late afternoon and into the evening, convection -- and local risk for strong/damaging winds -- will spread eastward toward/into the High Plains, before weakening into the overnight hours. ..Goss.. 09/02/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0101 AM CDT Mon Sep 02 2024 Valid 031200Z - 041200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN INTERMOUNTAIN REGION AND GREAT BASIN... ...SUMMARY... Scattered strong/a few severe storms capable of producing damaging wind gusts, and possibly marginal hail, are expected from the northern Intermountain region eastward into the northern High Plains, and southward into Utah. ...Synopsis... As a large-scale upper trough continues to vacate the northeastern U.S. Tuesday, a second/short-wave trough initially situated over the Pacific Northwest will advance eastward across the northern Intermountain region/Great Basin. At the surface, a cold front will shift eastward across the northwestern quarter of the country, in conjunction with the advancing upper trough, while westerly flow aloft will maintain a High-Plains lee trough. Meanwhile, a remnant baroclinic zone will linger from the southern Atlantic coastal area westward across the Gulf Coast/northern Gulf of Mexico through the period, as a large area of high pressure prevails north of the front, across the central and eastern U.S., through the period. ...Montana to the western Dakotas, and southward to northwestern Colorado and Utah... As the upper system advances eastward across Idaho/western Montana and the Great Basin during the afternoon, daytime heating/mixing will eventually result in 500 to 1000 J/kg mixed-layer CAPE atop a deep/dry boundary layer. This will support development of scattered thunderstorms from western Montana/eastern Idaho southward across Utah and adjacent portions of eastern Nevada. The strongest storms are expected to evolve from southwestern Montana south to northern Utah, where CAPE should be maximized ahead of the trough, and a belt of 30 to 40 kt west-southwesterly mid-level flow on the southeastern periphery of the upper trough should reside. Here, a couple of the strongest -- potentially rotating -- storms will be capable of producing both strong/severe outflow winds and possibly marginal hail. Surrounding this area, where instability and/or shear should remain a bit weaker, the primary risk will be isolated strong wind gusts. Through late afternoon and into the evening, convection -- and local risk for strong/damaging winds -- will spread eastward toward/into the High Plains, before weakening into the overnight hours. ..Goss.. 09/02/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0101 AM CDT Mon Sep 02 2024 Valid 031200Z - 041200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN INTERMOUNTAIN REGION AND GREAT BASIN... ...SUMMARY... Scattered strong/a few severe storms capable of producing damaging wind gusts, and possibly marginal hail, are expected from the northern Intermountain region eastward into the northern High Plains, and southward into Utah. ...Synopsis... As a large-scale upper trough continues to vacate the northeastern U.S. Tuesday, a second/short-wave trough initially situated over the Pacific Northwest will advance eastward across the northern Intermountain region/Great Basin. At the surface, a cold front will shift eastward across the northwestern quarter of the country, in conjunction with the advancing upper trough, while westerly flow aloft will maintain a High-Plains lee trough. Meanwhile, a remnant baroclinic zone will linger from the southern Atlantic coastal area westward across the Gulf Coast/northern Gulf of Mexico through the period, as a large area of high pressure prevails north of the front, across the central and eastern U.S., through the period. ...Montana to the western Dakotas, and southward to northwestern Colorado and Utah... As the upper system advances eastward across Idaho/western Montana and the Great Basin during the afternoon, daytime heating/mixing will eventually result in 500 to 1000 J/kg mixed-layer CAPE atop a deep/dry boundary layer. This will support development of scattered thunderstorms from western Montana/eastern Idaho southward across Utah and adjacent portions of eastern Nevada. The strongest storms are expected to evolve from southwestern Montana south to northern Utah, where CAPE should be maximized ahead of the trough, and a belt of 30 to 40 kt west-southwesterly mid-level flow on the southeastern periphery of the upper trough should reside. Here, a couple of the strongest -- potentially rotating -- storms will be capable of producing both strong/severe outflow winds and possibly marginal hail. Surrounding this area, where instability and/or shear should remain a bit weaker, the primary risk will be isolated strong wind gusts. Through late afternoon and into the evening, convection -- and local risk for strong/damaging winds -- will spread eastward toward/into the High Plains, before weakening into the overnight hours. ..Goss.. 09/02/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0101 AM CDT Mon Sep 02 2024 Valid 031200Z - 041200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN INTERMOUNTAIN REGION AND GREAT BASIN... ...SUMMARY... Scattered strong/a few severe storms capable of producing damaging wind gusts, and possibly marginal hail, are expected from the northern Intermountain region eastward into the northern High Plains, and southward into Utah. ...Synopsis... As a large-scale upper trough continues to vacate the northeastern U.S. Tuesday, a second/short-wave trough initially situated over the Pacific Northwest will advance eastward across the northern Intermountain region/Great Basin. At the surface, a cold front will shift eastward across the northwestern quarter of the country, in conjunction with the advancing upper trough, while westerly flow aloft will maintain a High-Plains lee trough. Meanwhile, a remnant baroclinic zone will linger from the southern Atlantic coastal area westward across the Gulf Coast/northern Gulf of Mexico through the period, as a large area of high pressure prevails north of the front, across the central and eastern U.S., through the period. ...Montana to the western Dakotas, and southward to northwestern Colorado and Utah... As the upper system advances eastward across Idaho/western Montana and the Great Basin during the afternoon, daytime heating/mixing will eventually result in 500 to 1000 J/kg mixed-layer CAPE atop a deep/dry boundary layer. This will support development of scattered thunderstorms from western Montana/eastern Idaho southward across Utah and adjacent portions of eastern Nevada. The strongest storms are expected to evolve from southwestern Montana south to northern Utah, where CAPE should be maximized ahead of the trough, and a belt of 30 to 40 kt west-southwesterly mid-level flow on the southeastern periphery of the upper trough should reside. Here, a couple of the strongest -- potentially rotating -- storms will be capable of producing both strong/severe outflow winds and possibly marginal hail. Surrounding this area, where instability and/or shear should remain a bit weaker, the primary risk will be isolated strong wind gusts. Through late afternoon and into the evening, convection -- and local risk for strong/damaging winds -- will spread eastward toward/into the High Plains, before weakening into the overnight hours. ..Goss.. 09/02/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0101 AM CDT Mon Sep 02 2024 Valid 031200Z - 041200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN INTERMOUNTAIN REGION AND GREAT BASIN... ...SUMMARY... Scattered strong/a few severe storms capable of producing damaging wind gusts, and possibly marginal hail, are expected from the northern Intermountain region eastward into the northern High Plains, and southward into Utah. ...Synopsis... As a large-scale upper trough continues to vacate the northeastern U.S. Tuesday, a second/short-wave trough initially situated over the Pacific Northwest will advance eastward across the northern Intermountain region/Great Basin. At the surface, a cold front will shift eastward across the northwestern quarter of the country, in conjunction with the advancing upper trough, while westerly flow aloft will maintain a High-Plains lee trough. Meanwhile, a remnant baroclinic zone will linger from the southern Atlantic coastal area westward across the Gulf Coast/northern Gulf of Mexico through the period, as a large area of high pressure prevails north of the front, across the central and eastern U.S., through the period. ...Montana to the western Dakotas, and southward to northwestern Colorado and Utah... As the upper system advances eastward across Idaho/western Montana and the Great Basin during the afternoon, daytime heating/mixing will eventually result in 500 to 1000 J/kg mixed-layer CAPE atop a deep/dry boundary layer. This will support development of scattered thunderstorms from western Montana/eastern Idaho southward across Utah and adjacent portions of eastern Nevada. The strongest storms are expected to evolve from southwestern Montana south to northern Utah, where CAPE should be maximized ahead of the trough, and a belt of 30 to 40 kt west-southwesterly mid-level flow on the southeastern periphery of the upper trough should reside. Here, a couple of the strongest -- potentially rotating -- storms will be capable of producing both strong/severe outflow winds and possibly marginal hail. Surrounding this area, where instability and/or shear should remain a bit weaker, the primary risk will be isolated strong wind gusts. Through late afternoon and into the evening, convection -- and local risk for strong/damaging winds -- will spread eastward toward/into the High Plains, before weakening into the overnight hours. ..Goss.. 09/02/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0101 AM CDT Mon Sep 02 2024 Valid 031200Z - 041200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN INTERMOUNTAIN REGION AND GREAT BASIN... ...SUMMARY... Scattered strong/a few severe storms capable of producing damaging wind gusts, and possibly marginal hail, are expected from the northern Intermountain region eastward into the northern High Plains, and southward into Utah. ...Synopsis... As a large-scale upper trough continues to vacate the northeastern U.S. Tuesday, a second/short-wave trough initially situated over the Pacific Northwest will advance eastward across the northern Intermountain region/Great Basin. At the surface, a cold front will shift eastward across the northwestern quarter of the country, in conjunction with the advancing upper trough, while westerly flow aloft will maintain a High-Plains lee trough. Meanwhile, a remnant baroclinic zone will linger from the southern Atlantic coastal area westward across the Gulf Coast/northern Gulf of Mexico through the period, as a large area of high pressure prevails north of the front, across the central and eastern U.S., through the period. ...Montana to the western Dakotas, and southward to northwestern Colorado and Utah... As the upper system advances eastward across Idaho/western Montana and the Great Basin during the afternoon, daytime heating/mixing will eventually result in 500 to 1000 J/kg mixed-layer CAPE atop a deep/dry boundary layer. This will support development of scattered thunderstorms from western Montana/eastern Idaho southward across Utah and adjacent portions of eastern Nevada. The strongest storms are expected to evolve from southwestern Montana south to northern Utah, where CAPE should be maximized ahead of the trough, and a belt of 30 to 40 kt west-southwesterly mid-level flow on the southeastern periphery of the upper trough should reside. Here, a couple of the strongest -- potentially rotating -- storms will be capable of producing both strong/severe outflow winds and possibly marginal hail. Surrounding this area, where instability and/or shear should remain a bit weaker, the primary risk will be isolated strong wind gusts. Through late afternoon and into the evening, convection -- and local risk for strong/damaging winds -- will spread eastward toward/into the High Plains, before weakening into the overnight hours. ..Goss.. 09/02/2024 Read more