Severe Storms

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0143 AM CDT Tue Aug 20 2024 Valid 211200Z - 221200Z ...Synopsis... Broad southwesterly mid-level flow, and a progressive shortwave trough moving through the northern Great Basin/Northwest U.S., will bring sustained dry/windy conditions to portions of Nevada, Utah, and Idaho on Wednesday. ...Dry/Windy... Deep boundary-layer mixing beneath broad southwesterly mid-level flow, and a progressive shortwave trough moving from northern Nevada/southern Oregon into Idaho and Montana, will be responsible for elevated fire-weather conditions across the Great Basin on Wednesday. High-resolution ensemble guidance suggests there may be a narrow corridor of critical fire-weather conditions across Nevada, where relative humidity values will drop into the single digits and winds could get as high as 20-25 MPH. This area currently overlaps with fuels that are not expected to be receptive to wildfire spread, with ERC values around the 60th-65th annual percentiles. However, with dry/windy conditions expected the preceding day, some additional curing of fuels can be expected, and critical highlights could be needed in subsequent updates. ...Dry Thunderstorms... A mix of wet and dry thunderstorms will be possible across southwestern Montana, with additional dry thunderstorm development likely across southern Colorado and northern New Mexico. However, current fuels guidance suggests that both of these regions are unlikely to be receptive to new ignitions and wildfire spread, with ERC values below the 60th annual percentile for both regions. ..Halbert/Squitieri.. 08/20/2024 ...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 0110 AM CDT Tue Aug 20 2024 Valid 201200Z - 211200Z ...Synopsis... Broad southwesterly mid-level flow, associated with a shortwave trough approaching the northern California Coast, will be responsible for bringing dry/breezy conditions to the Great Basin and portions of Idaho/Montana. ...Dry/Windy... Deep boundary-layer mixing beneath a modest 40-50kt mid-level jet will bring dry/windy conditions to portions of Nevada, far southeastern Oregon/southwestern Utah and portions of southwest Montana/northeast Idaho, where fuels guidance suggest ERC annual percentiles range between the 80th and 98th. Elevated fire-weather conditions are anticipated, with relative humidity values of 5-10% and winds around 15-20 MPH. Locally critical conditions are possible across portions of southern and central Nevada, where gusts may reach 25 MPH. However, this largely overlaps with an area where fuels are less receptive to wildfire spread, precluding critical highlights. ...Dry Thunderstorms... Some dry thunderstorms are possible across central Utah, where deeply mixed boundary-layer profiles, surface relative humidity values of 15-20%, storm motions of around 30 knots, and PWAT values between 0.5-0.9 will combine to support thunderstorm development while limiting wetting rainfall. However, current fuels guidance shows ERC annual percentiles below the 50th percentile, precluding any highlights at this time. ..Halbert/Squitieri.. 08/20/2024 ...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 0110 AM CDT Tue Aug 20 2024 Valid 201200Z - 211200Z ...Synopsis... Broad southwesterly mid-level flow, associated with a shortwave trough approaching the northern California Coast, will be responsible for bringing dry/breezy conditions to the Great Basin and portions of Idaho/Montana. ...Dry/Windy... Deep boundary-layer mixing beneath a modest 40-50kt mid-level jet will bring dry/windy conditions to portions of Nevada, far southeastern Oregon/southwestern Utah and portions of southwest Montana/northeast Idaho, where fuels guidance suggest ERC annual percentiles range between the 80th and 98th. Elevated fire-weather conditions are anticipated, with relative humidity values of 5-10% and winds around 15-20 MPH. Locally critical conditions are possible across portions of southern and central Nevada, where gusts may reach 25 MPH. However, this largely overlaps with an area where fuels are less receptive to wildfire spread, precluding critical highlights. ...Dry Thunderstorms... Some dry thunderstorms are possible across central Utah, where deeply mixed boundary-layer profiles, surface relative humidity values of 15-20%, storm motions of around 30 knots, and PWAT values between 0.5-0.9 will combine to support thunderstorm development while limiting wetting rainfall. However, current fuels guidance shows ERC annual percentiles below the 50th percentile, precluding any highlights at this time. ..Halbert/Squitieri.. 08/20/2024 ...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 0110 AM CDT Tue Aug 20 2024 Valid 201200Z - 211200Z ...Synopsis... Broad southwesterly mid-level flow, associated with a shortwave trough approaching the northern California Coast, will be responsible for bringing dry/breezy conditions to the Great Basin and portions of Idaho/Montana. ...Dry/Windy... Deep boundary-layer mixing beneath a modest 40-50kt mid-level jet will bring dry/windy conditions to portions of Nevada, far southeastern Oregon/southwestern Utah and portions of southwest Montana/northeast Idaho, where fuels guidance suggest ERC annual percentiles range between the 80th and 98th. Elevated fire-weather conditions are anticipated, with relative humidity values of 5-10% and winds around 15-20 MPH. Locally critical conditions are possible across portions of southern and central Nevada, where gusts may reach 25 MPH. However, this largely overlaps with an area where fuels are less receptive to wildfire spread, precluding critical highlights. ...Dry Thunderstorms... Some dry thunderstorms are possible across central Utah, where deeply mixed boundary-layer profiles, surface relative humidity values of 15-20%, storm motions of around 30 knots, and PWAT values between 0.5-0.9 will combine to support thunderstorm development while limiting wetting rainfall. However, current fuels guidance shows ERC annual percentiles below the 50th percentile, precluding any highlights at this time. ..Halbert/Squitieri.. 08/20/2024 ...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 0110 AM CDT Tue Aug 20 2024 Valid 201200Z - 211200Z ...Synopsis... Broad southwesterly mid-level flow, associated with a shortwave trough approaching the northern California Coast, will be responsible for bringing dry/breezy conditions to the Great Basin and portions of Idaho/Montana. ...Dry/Windy... Deep boundary-layer mixing beneath a modest 40-50kt mid-level jet will bring dry/windy conditions to portions of Nevada, far southeastern Oregon/southwestern Utah and portions of southwest Montana/northeast Idaho, where fuels guidance suggest ERC annual percentiles range between the 80th and 98th. Elevated fire-weather conditions are anticipated, with relative humidity values of 5-10% and winds around 15-20 MPH. Locally critical conditions are possible across portions of southern and central Nevada, where gusts may reach 25 MPH. However, this largely overlaps with an area where fuels are less receptive to wildfire spread, precluding critical highlights. ...Dry Thunderstorms... Some dry thunderstorms are possible across central Utah, where deeply mixed boundary-layer profiles, surface relative humidity values of 15-20%, storm motions of around 30 knots, and PWAT values between 0.5-0.9 will combine to support thunderstorm development while limiting wetting rainfall. However, current fuels guidance shows ERC annual percentiles below the 50th percentile, precluding any highlights at this time. ..Halbert/Squitieri.. 08/20/2024 ...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 0110 AM CDT Tue Aug 20 2024 Valid 201200Z - 211200Z ...Synopsis... Broad southwesterly mid-level flow, associated with a shortwave trough approaching the northern California Coast, will be responsible for bringing dry/breezy conditions to the Great Basin and portions of Idaho/Montana. ...Dry/Windy... Deep boundary-layer mixing beneath a modest 40-50kt mid-level jet will bring dry/windy conditions to portions of Nevada, far southeastern Oregon/southwestern Utah and portions of southwest Montana/northeast Idaho, where fuels guidance suggest ERC annual percentiles range between the 80th and 98th. Elevated fire-weather conditions are anticipated, with relative humidity values of 5-10% and winds around 15-20 MPH. Locally critical conditions are possible across portions of southern and central Nevada, where gusts may reach 25 MPH. However, this largely overlaps with an area where fuels are less receptive to wildfire spread, precluding critical highlights. ...Dry Thunderstorms... Some dry thunderstorms are possible across central Utah, where deeply mixed boundary-layer profiles, surface relative humidity values of 15-20%, storm motions of around 30 knots, and PWAT values between 0.5-0.9 will combine to support thunderstorm development while limiting wetting rainfall. However, current fuels guidance shows ERC annual percentiles below the 50th percentile, precluding any highlights at this time. ..Halbert/Squitieri.. 08/20/2024 ...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 1253 AM CDT Tue Aug 20 2024 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF EASTERN MONTANA AND WESTERN NORTH DAKOTA... ...SUMMARY... Scattered thunderstorms, some with severe hail and damaging gusts are expected to develop on Wednesday over parts of far eastern Montana and western North Dakota. ...Central and Northern Plains... An upper-level ridge is forecast to move eastward across the northern Plains on Wednesday, as a subtle shortwave trough moves into the northern High Plains in southwesterly mid-level flow. At the surface, a lee low in southeastern Montana is forecast to deepen ahead of an approaching front. Warming surface temperatures ahead of the front combined with surface dewpoints in the lower to mid 60s F, will likely result in a southeast-to-northwest corridor of moderate instability by afternoon. Thunderstorms appear likely to develop in the mid to late afternoon near the front and in the higher terrain of central and southern Montana. The models are now in better agreement concerning the magnitude of instability, with MLCAPE expected to reach the 3500 to 5000 J/kg range along the instability axis. Thunderstorms that move toward the instability axis will have a chance to be severe. Most NAM forecast soundings near the instability axis by 00Z/Thursday have 0-6 km shear in the 40 to 50 knot range with 700 to 500 mb lapse rates of 8 to 9 C/km. This would be favorable for supercells with large hail. Storm bases should be high due to large temperature-dewpoint spreads, which will contribute to the wind-damage potential. Far eastern Montana and western North Dakotas should be impacted during the evening, as low-level flow gradually ramps up. Further to the south into the central High Plains, an axis of moderate instability is forecast to develop by afternoon from west-central Nebraska south-southwestward into northeastern Colorado. By mid afternoon, thunderstorms are expected to form in the higher terrain of southern Wyoming and central Colorado, with this convection moving eastward into the lower elevations. Thunderstorms that move into the most and unstable airmass over the central High Plains will have a chance to become severe. 0-6 km shear around 30 knots combined with steep mid-level lapse rates will support an isolated threat for large hail and severe gusts, with the threat concentrated in the late afternoon and early evening. ..Broyles.. 08/20/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1253 AM CDT Tue Aug 20 2024 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF EASTERN MONTANA AND WESTERN NORTH DAKOTA... ...SUMMARY... Scattered thunderstorms, some with severe hail and damaging gusts are expected to develop on Wednesday over parts of far eastern Montana and western North Dakota. ...Central and Northern Plains... An upper-level ridge is forecast to move eastward across the northern Plains on Wednesday, as a subtle shortwave trough moves into the northern High Plains in southwesterly mid-level flow. At the surface, a lee low in southeastern Montana is forecast to deepen ahead of an approaching front. Warming surface temperatures ahead of the front combined with surface dewpoints in the lower to mid 60s F, will likely result in a southeast-to-northwest corridor of moderate instability by afternoon. Thunderstorms appear likely to develop in the mid to late afternoon near the front and in the higher terrain of central and southern Montana. The models are now in better agreement concerning the magnitude of instability, with MLCAPE expected to reach the 3500 to 5000 J/kg range along the instability axis. Thunderstorms that move toward the instability axis will have a chance to be severe. Most NAM forecast soundings near the instability axis by 00Z/Thursday have 0-6 km shear in the 40 to 50 knot range with 700 to 500 mb lapse rates of 8 to 9 C/km. This would be favorable for supercells with large hail. Storm bases should be high due to large temperature-dewpoint spreads, which will contribute to the wind-damage potential. Far eastern Montana and western North Dakotas should be impacted during the evening, as low-level flow gradually ramps up. Further to the south into the central High Plains, an axis of moderate instability is forecast to develop by afternoon from west-central Nebraska south-southwestward into northeastern Colorado. By mid afternoon, thunderstorms are expected to form in the higher terrain of southern Wyoming and central Colorado, with this convection moving eastward into the lower elevations. Thunderstorms that move into the most and unstable airmass over the central High Plains will have a chance to become severe. 0-6 km shear around 30 knots combined with steep mid-level lapse rates will support an isolated threat for large hail and severe gusts, with the threat concentrated in the late afternoon and early evening. ..Broyles.. 08/20/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1253 AM CDT Tue Aug 20 2024 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF EASTERN MONTANA AND WESTERN NORTH DAKOTA... ...SUMMARY... Scattered thunderstorms, some with severe hail and damaging gusts are expected to develop on Wednesday over parts of far eastern Montana and western North Dakota. ...Central and Northern Plains... An upper-level ridge is forecast to move eastward across the northern Plains on Wednesday, as a subtle shortwave trough moves into the northern High Plains in southwesterly mid-level flow. At the surface, a lee low in southeastern Montana is forecast to deepen ahead of an approaching front. Warming surface temperatures ahead of the front combined with surface dewpoints in the lower to mid 60s F, will likely result in a southeast-to-northwest corridor of moderate instability by afternoon. Thunderstorms appear likely to develop in the mid to late afternoon near the front and in the higher terrain of central and southern Montana. The models are now in better agreement concerning the magnitude of instability, with MLCAPE expected to reach the 3500 to 5000 J/kg range along the instability axis. Thunderstorms that move toward the instability axis will have a chance to be severe. Most NAM forecast soundings near the instability axis by 00Z/Thursday have 0-6 km shear in the 40 to 50 knot range with 700 to 500 mb lapse rates of 8 to 9 C/km. This would be favorable for supercells with large hail. Storm bases should be high due to large temperature-dewpoint spreads, which will contribute to the wind-damage potential. Far eastern Montana and western North Dakotas should be impacted during the evening, as low-level flow gradually ramps up. Further to the south into the central High Plains, an axis of moderate instability is forecast to develop by afternoon from west-central Nebraska south-southwestward into northeastern Colorado. By mid afternoon, thunderstorms are expected to form in the higher terrain of southern Wyoming and central Colorado, with this convection moving eastward into the lower elevations. Thunderstorms that move into the most and unstable airmass over the central High Plains will have a chance to become severe. 0-6 km shear around 30 knots combined with steep mid-level lapse rates will support an isolated threat for large hail and severe gusts, with the threat concentrated in the late afternoon and early evening. ..Broyles.. 08/20/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1253 AM CDT Tue Aug 20 2024 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF EASTERN MONTANA AND WESTERN NORTH DAKOTA... ...SUMMARY... Scattered thunderstorms, some with severe hail and damaging gusts are expected to develop on Wednesday over parts of far eastern Montana and western North Dakota. ...Central and Northern Plains... An upper-level ridge is forecast to move eastward across the northern Plains on Wednesday, as a subtle shortwave trough moves into the northern High Plains in southwesterly mid-level flow. At the surface, a lee low in southeastern Montana is forecast to deepen ahead of an approaching front. Warming surface temperatures ahead of the front combined with surface dewpoints in the lower to mid 60s F, will likely result in a southeast-to-northwest corridor of moderate instability by afternoon. Thunderstorms appear likely to develop in the mid to late afternoon near the front and in the higher terrain of central and southern Montana. The models are now in better agreement concerning the magnitude of instability, with MLCAPE expected to reach the 3500 to 5000 J/kg range along the instability axis. Thunderstorms that move toward the instability axis will have a chance to be severe. Most NAM forecast soundings near the instability axis by 00Z/Thursday have 0-6 km shear in the 40 to 50 knot range with 700 to 500 mb lapse rates of 8 to 9 C/km. This would be favorable for supercells with large hail. Storm bases should be high due to large temperature-dewpoint spreads, which will contribute to the wind-damage potential. Far eastern Montana and western North Dakotas should be impacted during the evening, as low-level flow gradually ramps up. Further to the south into the central High Plains, an axis of moderate instability is forecast to develop by afternoon from west-central Nebraska south-southwestward into northeastern Colorado. By mid afternoon, thunderstorms are expected to form in the higher terrain of southern Wyoming and central Colorado, with this convection moving eastward into the lower elevations. Thunderstorms that move into the most and unstable airmass over the central High Plains will have a chance to become severe. 0-6 km shear around 30 knots combined with steep mid-level lapse rates will support an isolated threat for large hail and severe gusts, with the threat concentrated in the late afternoon and early evening. ..Broyles.. 08/20/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1253 AM CDT Tue Aug 20 2024 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF EASTERN MONTANA AND WESTERN NORTH DAKOTA... ...SUMMARY... Scattered thunderstorms, some with severe hail and damaging gusts are expected to develop on Wednesday over parts of far eastern Montana and western North Dakota. ...Central and Northern Plains... An upper-level ridge is forecast to move eastward across the northern Plains on Wednesday, as a subtle shortwave trough moves into the northern High Plains in southwesterly mid-level flow. At the surface, a lee low in southeastern Montana is forecast to deepen ahead of an approaching front. Warming surface temperatures ahead of the front combined with surface dewpoints in the lower to mid 60s F, will likely result in a southeast-to-northwest corridor of moderate instability by afternoon. Thunderstorms appear likely to develop in the mid to late afternoon near the front and in the higher terrain of central and southern Montana. The models are now in better agreement concerning the magnitude of instability, with MLCAPE expected to reach the 3500 to 5000 J/kg range along the instability axis. Thunderstorms that move toward the instability axis will have a chance to be severe. Most NAM forecast soundings near the instability axis by 00Z/Thursday have 0-6 km shear in the 40 to 50 knot range with 700 to 500 mb lapse rates of 8 to 9 C/km. This would be favorable for supercells with large hail. Storm bases should be high due to large temperature-dewpoint spreads, which will contribute to the wind-damage potential. Far eastern Montana and western North Dakotas should be impacted during the evening, as low-level flow gradually ramps up. Further to the south into the central High Plains, an axis of moderate instability is forecast to develop by afternoon from west-central Nebraska south-southwestward into northeastern Colorado. By mid afternoon, thunderstorms are expected to form in the higher terrain of southern Wyoming and central Colorado, with this convection moving eastward into the lower elevations. Thunderstorms that move into the most and unstable airmass over the central High Plains will have a chance to become severe. 0-6 km shear around 30 knots combined with steep mid-level lapse rates will support an isolated threat for large hail and severe gusts, with the threat concentrated in the late afternoon and early evening. ..Broyles.. 08/20/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1253 AM CDT Tue Aug 20 2024 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF EASTERN MONTANA AND WESTERN NORTH DAKOTA... ...SUMMARY... Scattered thunderstorms, some with severe hail and damaging gusts are expected to develop on Wednesday over parts of far eastern Montana and western North Dakota. ...Central and Northern Plains... An upper-level ridge is forecast to move eastward across the northern Plains on Wednesday, as a subtle shortwave trough moves into the northern High Plains in southwesterly mid-level flow. At the surface, a lee low in southeastern Montana is forecast to deepen ahead of an approaching front. Warming surface temperatures ahead of the front combined with surface dewpoints in the lower to mid 60s F, will likely result in a southeast-to-northwest corridor of moderate instability by afternoon. Thunderstorms appear likely to develop in the mid to late afternoon near the front and in the higher terrain of central and southern Montana. The models are now in better agreement concerning the magnitude of instability, with MLCAPE expected to reach the 3500 to 5000 J/kg range along the instability axis. Thunderstorms that move toward the instability axis will have a chance to be severe. Most NAM forecast soundings near the instability axis by 00Z/Thursday have 0-6 km shear in the 40 to 50 knot range with 700 to 500 mb lapse rates of 8 to 9 C/km. This would be favorable for supercells with large hail. Storm bases should be high due to large temperature-dewpoint spreads, which will contribute to the wind-damage potential. Far eastern Montana and western North Dakotas should be impacted during the evening, as low-level flow gradually ramps up. Further to the south into the central High Plains, an axis of moderate instability is forecast to develop by afternoon from west-central Nebraska south-southwestward into northeastern Colorado. By mid afternoon, thunderstorms are expected to form in the higher terrain of southern Wyoming and central Colorado, with this convection moving eastward into the lower elevations. Thunderstorms that move into the most and unstable airmass over the central High Plains will have a chance to become severe. 0-6 km shear around 30 knots combined with steep mid-level lapse rates will support an isolated threat for large hail and severe gusts, with the threat concentrated in the late afternoon and early evening. ..Broyles.. 08/20/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1242 AM CDT Tue Aug 20 2024 Valid 201200Z - 211200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF MONTANA... ...SUMMARY... Widely scattered to scattered storms are possible in parts of central/eastern Montana with more isolated coverage into parts of the central High Plains. Severe winds and large hail are the primary threats. ...MT into the Central High Plains... Upper ridge is forecast to hold across the High Plains through the day1 period, though some weak mid-level height falls are expected across the northern Rockies in response to a very weak disturbance. With broad southwesterly flow entrenched across the northern intermountain region into central MT, a surface lee trough will arc from central MT-western Black Hills-eastern CO. This will ensure southeasterly boundary-layer winds are maintained across the northern High Plains into central MT. Strong surface heating will allow temperatures to warm into the 90s across eastern MT and convective temperatures should be breached at lower elevations by 20z. Latest thinking is scattered convection will develop over the higher terrain of southern MT then spread northeast toward the High Plains. NAM forecast sounding for LWT at 20z exhibits 2300 J/kg MLCAPE with 0-6km bulk shear around 50kt. This profile suggests supercells are likely, especially early in the convective cycle. Relatively high cloud bases favor strong gusts and this should be the primary risk, though large hail is certainly possible with supercells. Scattered convection should spread toward eastern MT where gradual weakening is expected during the late evening. Farther south, a very weak disturbance will rotate around the southern Rockies anticyclone into eastern CO by late afternoon. Scattered convection should easily develop over the higher terrain of southern CO then spread east along/north of a front that will be draped from northwest OK into southeast CO. Favorable veering wind profiles with height, along with 0-6km shear on the order of 30kt, suggests slow-moving supercells could spread east-southeast during the late afternoon/evening. Isolated hail/wind are the primary threats. ..Darrow/Halbert.. 08/20/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1242 AM CDT Tue Aug 20 2024 Valid 201200Z - 211200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF MONTANA... ...SUMMARY... Widely scattered to scattered storms are possible in parts of central/eastern Montana with more isolated coverage into parts of the central High Plains. Severe winds and large hail are the primary threats. ...MT into the Central High Plains... Upper ridge is forecast to hold across the High Plains through the day1 period, though some weak mid-level height falls are expected across the northern Rockies in response to a very weak disturbance. With broad southwesterly flow entrenched across the northern intermountain region into central MT, a surface lee trough will arc from central MT-western Black Hills-eastern CO. This will ensure southeasterly boundary-layer winds are maintained across the northern High Plains into central MT. Strong surface heating will allow temperatures to warm into the 90s across eastern MT and convective temperatures should be breached at lower elevations by 20z. Latest thinking is scattered convection will develop over the higher terrain of southern MT then spread northeast toward the High Plains. NAM forecast sounding for LWT at 20z exhibits 2300 J/kg MLCAPE with 0-6km bulk shear around 50kt. This profile suggests supercells are likely, especially early in the convective cycle. Relatively high cloud bases favor strong gusts and this should be the primary risk, though large hail is certainly possible with supercells. Scattered convection should spread toward eastern MT where gradual weakening is expected during the late evening. Farther south, a very weak disturbance will rotate around the southern Rockies anticyclone into eastern CO by late afternoon. Scattered convection should easily develop over the higher terrain of southern CO then spread east along/north of a front that will be draped from northwest OK into southeast CO. Favorable veering wind profiles with height, along with 0-6km shear on the order of 30kt, suggests slow-moving supercells could spread east-southeast during the late afternoon/evening. Isolated hail/wind are the primary threats. ..Darrow/Halbert.. 08/20/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1242 AM CDT Tue Aug 20 2024 Valid 201200Z - 211200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF MONTANA... ...SUMMARY... Widely scattered to scattered storms are possible in parts of central/eastern Montana with more isolated coverage into parts of the central High Plains. Severe winds and large hail are the primary threats. ...MT into the Central High Plains... Upper ridge is forecast to hold across the High Plains through the day1 period, though some weak mid-level height falls are expected across the northern Rockies in response to a very weak disturbance. With broad southwesterly flow entrenched across the northern intermountain region into central MT, a surface lee trough will arc from central MT-western Black Hills-eastern CO. This will ensure southeasterly boundary-layer winds are maintained across the northern High Plains into central MT. Strong surface heating will allow temperatures to warm into the 90s across eastern MT and convective temperatures should be breached at lower elevations by 20z. Latest thinking is scattered convection will develop over the higher terrain of southern MT then spread northeast toward the High Plains. NAM forecast sounding for LWT at 20z exhibits 2300 J/kg MLCAPE with 0-6km bulk shear around 50kt. This profile suggests supercells are likely, especially early in the convective cycle. Relatively high cloud bases favor strong gusts and this should be the primary risk, though large hail is certainly possible with supercells. Scattered convection should spread toward eastern MT where gradual weakening is expected during the late evening. Farther south, a very weak disturbance will rotate around the southern Rockies anticyclone into eastern CO by late afternoon. Scattered convection should easily develop over the higher terrain of southern CO then spread east along/north of a front that will be draped from northwest OK into southeast CO. Favorable veering wind profiles with height, along with 0-6km shear on the order of 30kt, suggests slow-moving supercells could spread east-southeast during the late afternoon/evening. Isolated hail/wind are the primary threats. ..Darrow/Halbert.. 08/20/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1242 AM CDT Tue Aug 20 2024 Valid 201200Z - 211200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF MONTANA... ...SUMMARY... Widely scattered to scattered storms are possible in parts of central/eastern Montana with more isolated coverage into parts of the central High Plains. Severe winds and large hail are the primary threats. ...MT into the Central High Plains... Upper ridge is forecast to hold across the High Plains through the day1 period, though some weak mid-level height falls are expected across the northern Rockies in response to a very weak disturbance. With broad southwesterly flow entrenched across the northern intermountain region into central MT, a surface lee trough will arc from central MT-western Black Hills-eastern CO. This will ensure southeasterly boundary-layer winds are maintained across the northern High Plains into central MT. Strong surface heating will allow temperatures to warm into the 90s across eastern MT and convective temperatures should be breached at lower elevations by 20z. Latest thinking is scattered convection will develop over the higher terrain of southern MT then spread northeast toward the High Plains. NAM forecast sounding for LWT at 20z exhibits 2300 J/kg MLCAPE with 0-6km bulk shear around 50kt. This profile suggests supercells are likely, especially early in the convective cycle. Relatively high cloud bases favor strong gusts and this should be the primary risk, though large hail is certainly possible with supercells. Scattered convection should spread toward eastern MT where gradual weakening is expected during the late evening. Farther south, a very weak disturbance will rotate around the southern Rockies anticyclone into eastern CO by late afternoon. Scattered convection should easily develop over the higher terrain of southern CO then spread east along/north of a front that will be draped from northwest OK into southeast CO. Favorable veering wind profiles with height, along with 0-6km shear on the order of 30kt, suggests slow-moving supercells could spread east-southeast during the late afternoon/evening. Isolated hail/wind are the primary threats. ..Darrow/Halbert.. 08/20/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1242 AM CDT Tue Aug 20 2024 Valid 201200Z - 211200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF MONTANA... ...SUMMARY... Widely scattered to scattered storms are possible in parts of central/eastern Montana with more isolated coverage into parts of the central High Plains. Severe winds and large hail are the primary threats. ...MT into the Central High Plains... Upper ridge is forecast to hold across the High Plains through the day1 period, though some weak mid-level height falls are expected across the northern Rockies in response to a very weak disturbance. With broad southwesterly flow entrenched across the northern intermountain region into central MT, a surface lee trough will arc from central MT-western Black Hills-eastern CO. This will ensure southeasterly boundary-layer winds are maintained across the northern High Plains into central MT. Strong surface heating will allow temperatures to warm into the 90s across eastern MT and convective temperatures should be breached at lower elevations by 20z. Latest thinking is scattered convection will develop over the higher terrain of southern MT then spread northeast toward the High Plains. NAM forecast sounding for LWT at 20z exhibits 2300 J/kg MLCAPE with 0-6km bulk shear around 50kt. This profile suggests supercells are likely, especially early in the convective cycle. Relatively high cloud bases favor strong gusts and this should be the primary risk, though large hail is certainly possible with supercells. Scattered convection should spread toward eastern MT where gradual weakening is expected during the late evening. Farther south, a very weak disturbance will rotate around the southern Rockies anticyclone into eastern CO by late afternoon. Scattered convection should easily develop over the higher terrain of southern CO then spread east along/north of a front that will be draped from northwest OK into southeast CO. Favorable veering wind profiles with height, along with 0-6km shear on the order of 30kt, suggests slow-moving supercells could spread east-southeast during the late afternoon/evening. Isolated hail/wind are the primary threats. ..Darrow/Halbert.. 08/20/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1242 AM CDT Tue Aug 20 2024 Valid 201200Z - 211200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF MONTANA... ...SUMMARY... Widely scattered to scattered storms are possible in parts of central/eastern Montana with more isolated coverage into parts of the central High Plains. Severe winds and large hail are the primary threats. ...MT into the Central High Plains... Upper ridge is forecast to hold across the High Plains through the day1 period, though some weak mid-level height falls are expected across the northern Rockies in response to a very weak disturbance. With broad southwesterly flow entrenched across the northern intermountain region into central MT, a surface lee trough will arc from central MT-western Black Hills-eastern CO. This will ensure southeasterly boundary-layer winds are maintained across the northern High Plains into central MT. Strong surface heating will allow temperatures to warm into the 90s across eastern MT and convective temperatures should be breached at lower elevations by 20z. Latest thinking is scattered convection will develop over the higher terrain of southern MT then spread northeast toward the High Plains. NAM forecast sounding for LWT at 20z exhibits 2300 J/kg MLCAPE with 0-6km bulk shear around 50kt. This profile suggests supercells are likely, especially early in the convective cycle. Relatively high cloud bases favor strong gusts and this should be the primary risk, though large hail is certainly possible with supercells. Scattered convection should spread toward eastern MT where gradual weakening is expected during the late evening. Farther south, a very weak disturbance will rotate around the southern Rockies anticyclone into eastern CO by late afternoon. Scattered convection should easily develop over the higher terrain of southern CO then spread east along/north of a front that will be draped from northwest OK into southeast CO. Favorable veering wind profiles with height, along with 0-6km shear on the order of 30kt, suggests slow-moving supercells could spread east-southeast during the late afternoon/evening. Isolated hail/wind are the primary threats. ..Darrow/Halbert.. 08/20/2024 Read more

MD 1962 CONCERNING SEVERE THUNDERSTORM WATCH 640... FOR NORTH-CENTRAL MONTANA
Mesoscale Discussion 1962 NWS Storm Prediction Center Norman OK 0931 PM CDT Mon Aug 19 2024 Areas affected...north-central Montana Concerning...Severe Thunderstorm Watch 640... Valid 200231Z - 200400Z The severe weather threat for Severe Thunderstorm Watch 640 continues. SUMMARY...Risk for locally damaging wind gusts continues across parts of north-central Montana, in/near WW 640. DISCUSSION...Latest radar loop shows that as storms have descended from higher elevations into a more moist/unstable airmass, intensification/organization of the storms into a loose banded structure has occurred. The convection is moving northeastward at around 40 kt, and has produced wind gusts in the 50 to 60 MPH range over the past hour, along with small hail. Expect risk for damaging wind gusts to continue locally over the next hour or so, before storms weaken -- and begin moving across the international border. This should correspond well to the currently scheduled 20/04Z expiration time set for WW 640. ..Goss.. 08/20/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BYZ...GGW...TFX... LAT...LON 47961130 48241110 48841063 48920826 47100859 46680943 47091000 47631058 47961130 Read more

WW 0639 Status Updates
STATUS REPORT ON WW 639 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 15 NE DEN TO 35 WNW AKO TO 30 NNE AKO TO 40 ENE SNY AND 30 WSW PUB TO 35 SSE ITR TO 45 NNW GLD TO 30 W AKO. ..HALBERT..08/20/24 ATTN...WFO...GLD...PUB...BOU...CYS... STATUS REPORT FOR WS 639 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS COC025-061-089-101-121-200340- CO . COLORADO COUNTIES INCLUDED ARE CROWLEY KIOWA OTERO PUEBLO WASHINGTON THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more