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SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1229 PM CDT Sun Aug 17 2025 Valid 181200Z - 191200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS WITHIN THE CENTRAL/NORTHERN PLAINS AND UPPER MIDWEST... ...SUMMARY... Strong to severe storms capable of damaging winds are possible in parts of the Upper Midwest on Monday. Isolated to widely scattered storms could produce large hail and severe winds in parts of the central/northern Plains. ...Northern/Central Plains... Isolated to widely scattered storms to develop either along a weak surface trough, within the terrain in eastern Wyoming/Black Hills, or a cold front near the Nebraska/South Dakota border. Strong buoyancy and effective shear of 30-40 kts will allow for the stronger storms to be organized. Large hail and severe winds would be the expected hazards. There is some potential for a more organized cluster of storms to progress eastward. This would most likely occur near the cold front during late afternoon/evening. However, a very weak low-level jet and uncertain cold pool organization keeps confidence too low for any increase in wind probabilities. ...Upper Midwest... Showers/thunderstorms are expected to be ongoing Monday morning. This will have an impact on where the greatest destabilization will occur during the afternoon. Furthermore, the region will be in the wake of a departing shortwave trough/MCV with mid-level ascent being nebulous and uncertain. Current guidance suggests the greatest potential for afternoon storms will exist in parts of central/southern Wisconsin into northern Illinois. There, some surface heating and low-level lift near a weak surface low/triple point could promote widely scattered to scattered thunderstorms. While the exact placement of this activity remains uncertain, the environment would support marginal supercells and multicell clusters with a primary hazard of damaging winds. Farther southwest into Iowa, strong buoyancy is expected to develop south of any outflow from morning activity. MLCAPE around 3000 J/kg would support a threat for isolated wind damage even with weaker effective shear than farther north. However, with little in the way of mid-level ascent and uncertain low-level forcing gives low confidence in storm coverage. ...Southwest into central Montana... Though a ridge will be building into the northern Rockies, sufficient moisture may promote thunderstorm development in the higher terrain. Flow aloft will be strong enough to support at least marginally organized storms. However, it is not clear how intense storms will be given some signal for moisture to mix out during the afternoon. Strong, gusty outflow winds are possible, but confidence in severe potential remains low. ..Wendt.. 08/17/2025 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1229 PM CDT Sun Aug 17 2025 Valid 181200Z - 191200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS WITHIN THE CENTRAL/NORTHERN PLAINS AND UPPER MIDWEST... ...SUMMARY... Strong to severe storms capable of damaging winds are possible in parts of the Upper Midwest on Monday. Isolated to widely scattered storms could produce large hail and severe winds in parts of the central/northern Plains. ...Northern/Central Plains... Isolated to widely scattered storms to develop either along a weak surface trough, within the terrain in eastern Wyoming/Black Hills, or a cold front near the Nebraska/South Dakota border. Strong buoyancy and effective shear of 30-40 kts will allow for the stronger storms to be organized. Large hail and severe winds would be the expected hazards. There is some potential for a more organized cluster of storms to progress eastward. This would most likely occur near the cold front during late afternoon/evening. However, a very weak low-level jet and uncertain cold pool organization keeps confidence too low for any increase in wind probabilities. ...Upper Midwest... Showers/thunderstorms are expected to be ongoing Monday morning. This will have an impact on where the greatest destabilization will occur during the afternoon. Furthermore, the region will be in the wake of a departing shortwave trough/MCV with mid-level ascent being nebulous and uncertain. Current guidance suggests the greatest potential for afternoon storms will exist in parts of central/southern Wisconsin into northern Illinois. There, some surface heating and low-level lift near a weak surface low/triple point could promote widely scattered to scattered thunderstorms. While the exact placement of this activity remains uncertain, the environment would support marginal supercells and multicell clusters with a primary hazard of damaging winds. Farther southwest into Iowa, strong buoyancy is expected to develop south of any outflow from morning activity. MLCAPE around 3000 J/kg would support a threat for isolated wind damage even with weaker effective shear than farther north. However, with little in the way of mid-level ascent and uncertain low-level forcing gives low confidence in storm coverage. ...Southwest into central Montana... Though a ridge will be building into the northern Rockies, sufficient moisture may promote thunderstorm development in the higher terrain. Flow aloft will be strong enough to support at least marginally organized storms. However, it is not clear how intense storms will be given some signal for moisture to mix out during the afternoon. Strong, gusty outflow winds are possible, but confidence in severe potential remains low. ..Wendt.. 08/17/2025 Read more

MD 1973 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR SOUTHWEST PENNSYLVANIA
Mesoscale Discussion 1973 NWS Storm Prediction Center Norman OK 1139 AM CDT Sun Aug 17 2025 Areas affected...southwest Pennsylvania Concerning...Severe potential...Watch unlikely Valid 171639Z - 171745Z Probability of Watch Issuance...5 percent SUMMARY...A few strong storms are possible across southwest Pennsylvania through early afternoon. DISCUSSION...A few storms have developed across southwest Pennsylvania along a southward moving surface trough. Surface heating has resulted in some instability, but weak mid-level lapse rates on the 12Z PIT RAOB are limiting overall buoyancy. Nonetheless, a few stronger storms along this front could produce occasional damaging winds (evidenced by a recent 39 knot gust at KPIT). However, any severe wind threat should be very isolated given weak shear (19 knots on 12Z PIT RAOB) and the aforementioned thermodynamic concerns. A severe thunderstorm watch is not anticipated. ..Bentley/Mosier.. 08/17/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...CTP...LWX...PBZ... LAT...LON 40718051 40807882 40547769 40017759 39727823 39697928 39698019 39868060 40138071 40718051 MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH Read more

381
ABPZ20 KNHC 171721
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
1100 AM PDT Sun Aug 17 2025

For the eastern and central North Pacific east of 180 longitude:

Tropical cyclone formation is not expected during the next 7 days.

$$
Forecaster Roberts

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1143 AM CDT Sun Aug 17 2025 Valid 171700Z - 181200Z ...Dry Thunder Northern Rockies/northern Great Basin... A mid-level trough and weak frontal boundary interacting with residual monsoon moisture, along with daytime instability will contribute to another round of thunderstorms mainly over the portions of central/southern ID and far northern NV. Higher atmospheric moisture content with PWAT values around 1.00 inch and surface dewpoints in the 50s could support wetter rain cores across central ID. However, faster northeast storm trajectories of up to 30 knots will limit residence time, likely leading to a mixed wet/dry thunderstorm environment this afternoon. Farther south where monsoon moisture decreases, isolated dry thunderstorm development and new lightning ignitions are possible along higher terrain south of the Snake River Plain into far northern Nevada, where fuels remain receptive. ...Eastern Great Basin... Dry and breezy conditions are still expected for much of eastern NV and west-central UT today aided by broad southwest flow southeast of the mid-level trough situated over the Northwestern U.S. Sustained southwest surface winds of 10-15 mph, localized 20 mph in southern NV/western UT, relative humidity of 10-15 percent range and dry fuels will support increased fire spread potential. ..Williams.. 08/17/2025 .PREV DISCUSSION... /ISSUED 0200 AM CDT Sun Aug 17 2025/ ...Synopsis... Broad ridging is forecast to expand over the central US today and tonight as a mid-level trough strengthens over the West. Monsoon moisture will lift north ahead of the trough and surface cold front supporting scattered showers and a few dry thunderstorms. Dry and breezy conditions are also possible over parts of the Southwest. ...Dry Thunder Northern Rockies... As western US troughing gradually consolidates, stronger mid-level flow will move eastward across the northern Great Basin and Rockies. The surface cold front will impinge on the western edge of monsoon moisture over the regions supporting another day of showers and thunderstorms. With PWATs near 1 inch, a wetter storm mode is expected, along with some wetting rainfall. Still, the increased flow aloft and faster storm speeds could support a few storms with lower precipitation efficiency. With the threat for lightning overlapping with drier fuels (especially east) isolated dry thunderstorms remain possible. ...Eastern Great Basin... South of the intensifying upper trough, enhanced southwesterly flow will overspread portions of the Great Basin beneath the western fringes of the upper ridge. Very warm temperatures are expected and fuels remain very dry/receptive to spread. A modest increase in surface winds to near 15 mph is expected through the afternoon along with RH below 15%. With some record to near record high ERC values remaining across portions of the Great Basin, a few hours of Elevated fire-weather conditions are possible. ...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 1143 AM CDT Sun Aug 17 2025 Valid 171700Z - 181200Z ...Dry Thunder Northern Rockies/northern Great Basin... A mid-level trough and weak frontal boundary interacting with residual monsoon moisture, along with daytime instability will contribute to another round of thunderstorms mainly over the portions of central/southern ID and far northern NV. Higher atmospheric moisture content with PWAT values around 1.00 inch and surface dewpoints in the 50s could support wetter rain cores across central ID. However, faster northeast storm trajectories of up to 30 knots will limit residence time, likely leading to a mixed wet/dry thunderstorm environment this afternoon. Farther south where monsoon moisture decreases, isolated dry thunderstorm development and new lightning ignitions are possible along higher terrain south of the Snake River Plain into far northern Nevada, where fuels remain receptive. ...Eastern Great Basin... Dry and breezy conditions are still expected for much of eastern NV and west-central UT today aided by broad southwest flow southeast of the mid-level trough situated over the Northwestern U.S. Sustained southwest surface winds of 10-15 mph, localized 20 mph in southern NV/western UT, relative humidity of 10-15 percent range and dry fuels will support increased fire spread potential. ..Williams.. 08/17/2025 .PREV DISCUSSION... /ISSUED 0200 AM CDT Sun Aug 17 2025/ ...Synopsis... Broad ridging is forecast to expand over the central US today and tonight as a mid-level trough strengthens over the West. Monsoon moisture will lift north ahead of the trough and surface cold front supporting scattered showers and a few dry thunderstorms. Dry and breezy conditions are also possible over parts of the Southwest. ...Dry Thunder Northern Rockies... As western US troughing gradually consolidates, stronger mid-level flow will move eastward across the northern Great Basin and Rockies. The surface cold front will impinge on the western edge of monsoon moisture over the regions supporting another day of showers and thunderstorms. With PWATs near 1 inch, a wetter storm mode is expected, along with some wetting rainfall. Still, the increased flow aloft and faster storm speeds could support a few storms with lower precipitation efficiency. With the threat for lightning overlapping with drier fuels (especially east) isolated dry thunderstorms remain possible. ...Eastern Great Basin... South of the intensifying upper trough, enhanced southwesterly flow will overspread portions of the Great Basin beneath the western fringes of the upper ridge. Very warm temperatures are expected and fuels remain very dry/receptive to spread. A modest increase in surface winds to near 15 mph is expected through the afternoon along with RH below 15%. With some record to near record high ERC values remaining across portions of the Great Basin, a few hours of Elevated fire-weather conditions are possible. ...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 1143 AM CDT Sun Aug 17 2025 Valid 171700Z - 181200Z ...Dry Thunder Northern Rockies/northern Great Basin... A mid-level trough and weak frontal boundary interacting with residual monsoon moisture, along with daytime instability will contribute to another round of thunderstorms mainly over the portions of central/southern ID and far northern NV. Higher atmospheric moisture content with PWAT values around 1.00 inch and surface dewpoints in the 50s could support wetter rain cores across central ID. However, faster northeast storm trajectories of up to 30 knots will limit residence time, likely leading to a mixed wet/dry thunderstorm environment this afternoon. Farther south where monsoon moisture decreases, isolated dry thunderstorm development and new lightning ignitions are possible along higher terrain south of the Snake River Plain into far northern Nevada, where fuels remain receptive. ...Eastern Great Basin... Dry and breezy conditions are still expected for much of eastern NV and west-central UT today aided by broad southwest flow southeast of the mid-level trough situated over the Northwestern U.S. Sustained southwest surface winds of 10-15 mph, localized 20 mph in southern NV/western UT, relative humidity of 10-15 percent range and dry fuels will support increased fire spread potential. ..Williams.. 08/17/2025 .PREV DISCUSSION... /ISSUED 0200 AM CDT Sun Aug 17 2025/ ...Synopsis... Broad ridging is forecast to expand over the central US today and tonight as a mid-level trough strengthens over the West. Monsoon moisture will lift north ahead of the trough and surface cold front supporting scattered showers and a few dry thunderstorms. Dry and breezy conditions are also possible over parts of the Southwest. ...Dry Thunder Northern Rockies... As western US troughing gradually consolidates, stronger mid-level flow will move eastward across the northern Great Basin and Rockies. The surface cold front will impinge on the western edge of monsoon moisture over the regions supporting another day of showers and thunderstorms. With PWATs near 1 inch, a wetter storm mode is expected, along with some wetting rainfall. Still, the increased flow aloft and faster storm speeds could support a few storms with lower precipitation efficiency. With the threat for lightning overlapping with drier fuels (especially east) isolated dry thunderstorms remain possible. ...Eastern Great Basin... South of the intensifying upper trough, enhanced southwesterly flow will overspread portions of the Great Basin beneath the western fringes of the upper ridge. Very warm temperatures are expected and fuels remain very dry/receptive to spread. A modest increase in surface winds to near 15 mph is expected through the afternoon along with RH below 15%. With some record to near record high ERC values remaining across portions of the Great Basin, a few hours of Elevated fire-weather conditions are possible. ...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 1143 AM CDT Sun Aug 17 2025 Valid 171700Z - 181200Z ...Dry Thunder Northern Rockies/northern Great Basin... A mid-level trough and weak frontal boundary interacting with residual monsoon moisture, along with daytime instability will contribute to another round of thunderstorms mainly over the portions of central/southern ID and far northern NV. Higher atmospheric moisture content with PWAT values around 1.00 inch and surface dewpoints in the 50s could support wetter rain cores across central ID. However, faster northeast storm trajectories of up to 30 knots will limit residence time, likely leading to a mixed wet/dry thunderstorm environment this afternoon. Farther south where monsoon moisture decreases, isolated dry thunderstorm development and new lightning ignitions are possible along higher terrain south of the Snake River Plain into far northern Nevada, where fuels remain receptive. ...Eastern Great Basin... Dry and breezy conditions are still expected for much of eastern NV and west-central UT today aided by broad southwest flow southeast of the mid-level trough situated over the Northwestern U.S. Sustained southwest surface winds of 10-15 mph, localized 20 mph in southern NV/western UT, relative humidity of 10-15 percent range and dry fuels will support increased fire spread potential. ..Williams.. 08/17/2025 .PREV DISCUSSION... /ISSUED 0200 AM CDT Sun Aug 17 2025/ ...Synopsis... Broad ridging is forecast to expand over the central US today and tonight as a mid-level trough strengthens over the West. Monsoon moisture will lift north ahead of the trough and surface cold front supporting scattered showers and a few dry thunderstorms. Dry and breezy conditions are also possible over parts of the Southwest. ...Dry Thunder Northern Rockies... As western US troughing gradually consolidates, stronger mid-level flow will move eastward across the northern Great Basin and Rockies. The surface cold front will impinge on the western edge of monsoon moisture over the regions supporting another day of showers and thunderstorms. With PWATs near 1 inch, a wetter storm mode is expected, along with some wetting rainfall. Still, the increased flow aloft and faster storm speeds could support a few storms with lower precipitation efficiency. With the threat for lightning overlapping with drier fuels (especially east) isolated dry thunderstorms remain possible. ...Eastern Great Basin... South of the intensifying upper trough, enhanced southwesterly flow will overspread portions of the Great Basin beneath the western fringes of the upper ridge. Very warm temperatures are expected and fuels remain very dry/receptive to spread. A modest increase in surface winds to near 15 mph is expected through the afternoon along with RH below 15%. With some record to near record high ERC values remaining across portions of the Great Basin, a few hours of Elevated fire-weather conditions are possible. ...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 1143 AM CDT Sun Aug 17 2025 Valid 171700Z - 181200Z ...Dry Thunder Northern Rockies/northern Great Basin... A mid-level trough and weak frontal boundary interacting with residual monsoon moisture, along with daytime instability will contribute to another round of thunderstorms mainly over the portions of central/southern ID and far northern NV. Higher atmospheric moisture content with PWAT values around 1.00 inch and surface dewpoints in the 50s could support wetter rain cores across central ID. However, faster northeast storm trajectories of up to 30 knots will limit residence time, likely leading to a mixed wet/dry thunderstorm environment this afternoon. Farther south where monsoon moisture decreases, isolated dry thunderstorm development and new lightning ignitions are possible along higher terrain south of the Snake River Plain into far northern Nevada, where fuels remain receptive. ...Eastern Great Basin... Dry and breezy conditions are still expected for much of eastern NV and west-central UT today aided by broad southwest flow southeast of the mid-level trough situated over the Northwestern U.S. Sustained southwest surface winds of 10-15 mph, localized 20 mph in southern NV/western UT, relative humidity of 10-15 percent range and dry fuels will support increased fire spread potential. ..Williams.. 08/17/2025 .PREV DISCUSSION... /ISSUED 0200 AM CDT Sun Aug 17 2025/ ...Synopsis... Broad ridging is forecast to expand over the central US today and tonight as a mid-level trough strengthens over the West. Monsoon moisture will lift north ahead of the trough and surface cold front supporting scattered showers and a few dry thunderstorms. Dry and breezy conditions are also possible over parts of the Southwest. ...Dry Thunder Northern Rockies... As western US troughing gradually consolidates, stronger mid-level flow will move eastward across the northern Great Basin and Rockies. The surface cold front will impinge on the western edge of monsoon moisture over the regions supporting another day of showers and thunderstorms. With PWATs near 1 inch, a wetter storm mode is expected, along with some wetting rainfall. Still, the increased flow aloft and faster storm speeds could support a few storms with lower precipitation efficiency. With the threat for lightning overlapping with drier fuels (especially east) isolated dry thunderstorms remain possible. ...Eastern Great Basin... South of the intensifying upper trough, enhanced southwesterly flow will overspread portions of the Great Basin beneath the western fringes of the upper ridge. Very warm temperatures are expected and fuels remain very dry/receptive to spread. A modest increase in surface winds to near 15 mph is expected through the afternoon along with RH below 15%. With some record to near record high ERC values remaining across portions of the Great Basin, a few hours of Elevated fire-weather conditions are possible. ...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 1143 AM CDT Sun Aug 17 2025 Valid 171700Z - 181200Z ...Dry Thunder Northern Rockies/northern Great Basin... A mid-level trough and weak frontal boundary interacting with residual monsoon moisture, along with daytime instability will contribute to another round of thunderstorms mainly over the portions of central/southern ID and far northern NV. Higher atmospheric moisture content with PWAT values around 1.00 inch and surface dewpoints in the 50s could support wetter rain cores across central ID. However, faster northeast storm trajectories of up to 30 knots will limit residence time, likely leading to a mixed wet/dry thunderstorm environment this afternoon. Farther south where monsoon moisture decreases, isolated dry thunderstorm development and new lightning ignitions are possible along higher terrain south of the Snake River Plain into far northern Nevada, where fuels remain receptive. ...Eastern Great Basin... Dry and breezy conditions are still expected for much of eastern NV and west-central UT today aided by broad southwest flow southeast of the mid-level trough situated over the Northwestern U.S. Sustained southwest surface winds of 10-15 mph, localized 20 mph in southern NV/western UT, relative humidity of 10-15 percent range and dry fuels will support increased fire spread potential. ..Williams.. 08/17/2025 .PREV DISCUSSION... /ISSUED 0200 AM CDT Sun Aug 17 2025/ ...Synopsis... Broad ridging is forecast to expand over the central US today and tonight as a mid-level trough strengthens over the West. Monsoon moisture will lift north ahead of the trough and surface cold front supporting scattered showers and a few dry thunderstorms. Dry and breezy conditions are also possible over parts of the Southwest. ...Dry Thunder Northern Rockies... As western US troughing gradually consolidates, stronger mid-level flow will move eastward across the northern Great Basin and Rockies. The surface cold front will impinge on the western edge of monsoon moisture over the regions supporting another day of showers and thunderstorms. With PWATs near 1 inch, a wetter storm mode is expected, along with some wetting rainfall. Still, the increased flow aloft and faster storm speeds could support a few storms with lower precipitation efficiency. With the threat for lightning overlapping with drier fuels (especially east) isolated dry thunderstorms remain possible. ...Eastern Great Basin... South of the intensifying upper trough, enhanced southwesterly flow will overspread portions of the Great Basin beneath the western fringes of the upper ridge. Very warm temperatures are expected and fuels remain very dry/receptive to spread. A modest increase in surface winds to near 15 mph is expected through the afternoon along with RH below 15%. With some record to near record high ERC values remaining across portions of the Great Basin, a few hours of Elevated fire-weather conditions are possible. ...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 1143 AM CDT Sun Aug 17 2025 Valid 171700Z - 181200Z ...Dry Thunder Northern Rockies/northern Great Basin... A mid-level trough and weak frontal boundary interacting with residual monsoon moisture, along with daytime instability will contribute to another round of thunderstorms mainly over the portions of central/southern ID and far northern NV. Higher atmospheric moisture content with PWAT values around 1.00 inch and surface dewpoints in the 50s could support wetter rain cores across central ID. However, faster northeast storm trajectories of up to 30 knots will limit residence time, likely leading to a mixed wet/dry thunderstorm environment this afternoon. Farther south where monsoon moisture decreases, isolated dry thunderstorm development and new lightning ignitions are possible along higher terrain south of the Snake River Plain into far northern Nevada, where fuels remain receptive. ...Eastern Great Basin... Dry and breezy conditions are still expected for much of eastern NV and west-central UT today aided by broad southwest flow southeast of the mid-level trough situated over the Northwestern U.S. Sustained southwest surface winds of 10-15 mph, localized 20 mph in southern NV/western UT, relative humidity of 10-15 percent range and dry fuels will support increased fire spread potential. ..Williams.. 08/17/2025 .PREV DISCUSSION... /ISSUED 0200 AM CDT Sun Aug 17 2025/ ...Synopsis... Broad ridging is forecast to expand over the central US today and tonight as a mid-level trough strengthens over the West. Monsoon moisture will lift north ahead of the trough and surface cold front supporting scattered showers and a few dry thunderstorms. Dry and breezy conditions are also possible over parts of the Southwest. ...Dry Thunder Northern Rockies... As western US troughing gradually consolidates, stronger mid-level flow will move eastward across the northern Great Basin and Rockies. The surface cold front will impinge on the western edge of monsoon moisture over the regions supporting another day of showers and thunderstorms. With PWATs near 1 inch, a wetter storm mode is expected, along with some wetting rainfall. Still, the increased flow aloft and faster storm speeds could support a few storms with lower precipitation efficiency. With the threat for lightning overlapping with drier fuels (especially east) isolated dry thunderstorms remain possible. ...Eastern Great Basin... South of the intensifying upper trough, enhanced southwesterly flow will overspread portions of the Great Basin beneath the western fringes of the upper ridge. Very warm temperatures are expected and fuels remain very dry/receptive to spread. A modest increase in surface winds to near 15 mph is expected through the afternoon along with RH below 15%. With some record to near record high ERC values remaining across portions of the Great Basin, a few hours of Elevated fire-weather conditions are possible. ...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 1143 AM CDT Sun Aug 17 2025 Valid 171700Z - 181200Z ...Dry Thunder Northern Rockies/northern Great Basin... A mid-level trough and weak frontal boundary interacting with residual monsoon moisture, along with daytime instability will contribute to another round of thunderstorms mainly over the portions of central/southern ID and far northern NV. Higher atmospheric moisture content with PWAT values around 1.00 inch and surface dewpoints in the 50s could support wetter rain cores across central ID. However, faster northeast storm trajectories of up to 30 knots will limit residence time, likely leading to a mixed wet/dry thunderstorm environment this afternoon. Farther south where monsoon moisture decreases, isolated dry thunderstorm development and new lightning ignitions are possible along higher terrain south of the Snake River Plain into far northern Nevada, where fuels remain receptive. ...Eastern Great Basin... Dry and breezy conditions are still expected for much of eastern NV and west-central UT today aided by broad southwest flow southeast of the mid-level trough situated over the Northwestern U.S. Sustained southwest surface winds of 10-15 mph, localized 20 mph in southern NV/western UT, relative humidity of 10-15 percent range and dry fuels will support increased fire spread potential. ..Williams.. 08/17/2025 .PREV DISCUSSION... /ISSUED 0200 AM CDT Sun Aug 17 2025/ ...Synopsis... Broad ridging is forecast to expand over the central US today and tonight as a mid-level trough strengthens over the West. Monsoon moisture will lift north ahead of the trough and surface cold front supporting scattered showers and a few dry thunderstorms. Dry and breezy conditions are also possible over parts of the Southwest. ...Dry Thunder Northern Rockies... As western US troughing gradually consolidates, stronger mid-level flow will move eastward across the northern Great Basin and Rockies. The surface cold front will impinge on the western edge of monsoon moisture over the regions supporting another day of showers and thunderstorms. With PWATs near 1 inch, a wetter storm mode is expected, along with some wetting rainfall. Still, the increased flow aloft and faster storm speeds could support a few storms with lower precipitation efficiency. With the threat for lightning overlapping with drier fuels (especially east) isolated dry thunderstorms remain possible. ...Eastern Great Basin... South of the intensifying upper trough, enhanced southwesterly flow will overspread portions of the Great Basin beneath the western fringes of the upper ridge. Very warm temperatures are expected and fuels remain very dry/receptive to spread. A modest increase in surface winds to near 15 mph is expected through the afternoon along with RH below 15%. With some record to near record high ERC values remaining across portions of the Great Basin, a few hours of Elevated fire-weather conditions are possible. ...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 1143 AM CDT Sun Aug 17 2025 Valid 171700Z - 181200Z ...Dry Thunder Northern Rockies/northern Great Basin... A mid-level trough and weak frontal boundary interacting with residual monsoon moisture, along with daytime instability will contribute to another round of thunderstorms mainly over the portions of central/southern ID and far northern NV. Higher atmospheric moisture content with PWAT values around 1.00 inch and surface dewpoints in the 50s could support wetter rain cores across central ID. However, faster northeast storm trajectories of up to 30 knots will limit residence time, likely leading to a mixed wet/dry thunderstorm environment this afternoon. Farther south where monsoon moisture decreases, isolated dry thunderstorm development and new lightning ignitions are possible along higher terrain south of the Snake River Plain into far northern Nevada, where fuels remain receptive. ...Eastern Great Basin... Dry and breezy conditions are still expected for much of eastern NV and west-central UT today aided by broad southwest flow southeast of the mid-level trough situated over the Northwestern U.S. Sustained southwest surface winds of 10-15 mph, localized 20 mph in southern NV/western UT, relative humidity of 10-15 percent range and dry fuels will support increased fire spread potential. ..Williams.. 08/17/2025 .PREV DISCUSSION... /ISSUED 0200 AM CDT Sun Aug 17 2025/ ...Synopsis... Broad ridging is forecast to expand over the central US today and tonight as a mid-level trough strengthens over the West. Monsoon moisture will lift north ahead of the trough and surface cold front supporting scattered showers and a few dry thunderstorms. Dry and breezy conditions are also possible over parts of the Southwest. ...Dry Thunder Northern Rockies... As western US troughing gradually consolidates, stronger mid-level flow will move eastward across the northern Great Basin and Rockies. The surface cold front will impinge on the western edge of monsoon moisture over the regions supporting another day of showers and thunderstorms. With PWATs near 1 inch, a wetter storm mode is expected, along with some wetting rainfall. Still, the increased flow aloft and faster storm speeds could support a few storms with lower precipitation efficiency. With the threat for lightning overlapping with drier fuels (especially east) isolated dry thunderstorms remain possible. ...Eastern Great Basin... South of the intensifying upper trough, enhanced southwesterly flow will overspread portions of the Great Basin beneath the western fringes of the upper ridge. Very warm temperatures are expected and fuels remain very dry/receptive to spread. A modest increase in surface winds to near 15 mph is expected through the afternoon along with RH below 15%. With some record to near record high ERC values remaining across portions of the Great Basin, a few hours of Elevated fire-weather conditions are possible. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Sun Aug 17 2025 Valid 171630Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE MIDDLE MISSOURI VALLEY VICINITY... ...SUMMARY... One or two clusters of thunderstorms may develop and gradually pose a risk for damaging wind gusts from the northern High Plains into the Midwest this afternoon and tonight. Damaging thunderstorm wind gusts may also occur across parts of the northern Mid Atlantic into southern New England late this afternoon and evening. ...Northern/Central Plains into Upper Midwest... The combination of close proximity to the upper ridge that covers much of the central/southern CONUS, lack of more defined synoptic features, and ample low-level moisture and buoyancy yields a complex and uncertain forecast from the northern/central Plains into the Midwest today and tonight. Recent satellite and radar imagery depicts two MCVs across the region, one over central SD and the other across central NE. Surface analysis also shows a low over the central SD/NE border, along the northern periphery of the NE MCV. A mix of convective outflow, cloud cover, and a formally more defined surface boundary has resulted in a warm-front-like feature extending southeastward from this surface low through central IA. All of these features will likely play a role in thunderstorm development today. The general expectation is for mesoscale ascent attendant to the surface low and MCV to yield increasing thunderstorm development across southeast SD and northeast NE over the next few hours. A sharpening warm front will likely shift northward, providing a favored corridor for storm progression, with the ongoing storms continuing downstream along this corridor into southwest MN and northwest/north-central IA. Damaging gusts will be the primary risk, with severe coverage expected to become high enough to merit introducing 15% wind probabilities. A more stable airmass to the north/northeast of the boundary should limit the severe risk over central MN and central WI. Much of the guidance also shows evening thunderstorm development beginning in eastern WY/southwest SD/NE Panhandle region before then spreading eastward/southeastward with time. This activity appears to be initially associated with low-level convergence along the lee troughing, with its progression southeastward likely tied to an increasing low-level jet. Isolated hail is possible initially with a few stronger gusts then possible overnight. ...Northern Rockies/northern High Plains... Scattered high-based thunderstorms are expected this afternoon and evening as ascent attendant the shortwave trough currently moving through eastern OR spreads into the region. Combination of moderate mid-level southwesterly flow, steep low-level lapse rates, and high cloud bases could contribute to isolated strong to severe gusts within these storms as they gradually move from southwest MT into central/southeastern MT. ...Mid Atlantic into southern New England... Recent surface analysis places a cold front from northern ME southwestward through western NY and northwest PA in northern OH. Mid-level lapse rates are weak, and the relatively warm profiles will likely limit buoyancy, despite dewpoints in the mid to upper 60s. However, strong heating into the 80s and 90s F and steep low-level lapse rates combined with modest westerly flow aloft and frontal forcing may be sufficient for isolated strong storms capable of locally gusty/damaging winds this afternoon. Locally higher probability for damaging gusts appears to exist across southern ME, where greater deep-layer shear is presence, and over the northern Mid-Atlantic where dewpoints and buoyancy will be highest. ..Mosier/Grams.. 08/17/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Sun Aug 17 2025 Valid 171630Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE MIDDLE MISSOURI VALLEY VICINITY... ...SUMMARY... One or two clusters of thunderstorms may develop and gradually pose a risk for damaging wind gusts from the northern High Plains into the Midwest this afternoon and tonight. Damaging thunderstorm wind gusts may also occur across parts of the northern Mid Atlantic into southern New England late this afternoon and evening. ...Northern/Central Plains into Upper Midwest... The combination of close proximity to the upper ridge that covers much of the central/southern CONUS, lack of more defined synoptic features, and ample low-level moisture and buoyancy yields a complex and uncertain forecast from the northern/central Plains into the Midwest today and tonight. Recent satellite and radar imagery depicts two MCVs across the region, one over central SD and the other across central NE. Surface analysis also shows a low over the central SD/NE border, along the northern periphery of the NE MCV. A mix of convective outflow, cloud cover, and a formally more defined surface boundary has resulted in a warm-front-like feature extending southeastward from this surface low through central IA. All of these features will likely play a role in thunderstorm development today. The general expectation is for mesoscale ascent attendant to the surface low and MCV to yield increasing thunderstorm development across southeast SD and northeast NE over the next few hours. A sharpening warm front will likely shift northward, providing a favored corridor for storm progression, with the ongoing storms continuing downstream along this corridor into southwest MN and northwest/north-central IA. Damaging gusts will be the primary risk, with severe coverage expected to become high enough to merit introducing 15% wind probabilities. A more stable airmass to the north/northeast of the boundary should limit the severe risk over central MN and central WI. Much of the guidance also shows evening thunderstorm development beginning in eastern WY/southwest SD/NE Panhandle region before then spreading eastward/southeastward with time. This activity appears to be initially associated with low-level convergence along the lee troughing, with its progression southeastward likely tied to an increasing low-level jet. Isolated hail is possible initially with a few stronger gusts then possible overnight. ...Northern Rockies/northern High Plains... Scattered high-based thunderstorms are expected this afternoon and evening as ascent attendant the shortwave trough currently moving through eastern OR spreads into the region. Combination of moderate mid-level southwesterly flow, steep low-level lapse rates, and high cloud bases could contribute to isolated strong to severe gusts within these storms as they gradually move from southwest MT into central/southeastern MT. ...Mid Atlantic into southern New England... Recent surface analysis places a cold front from northern ME southwestward through western NY and northwest PA in northern OH. Mid-level lapse rates are weak, and the relatively warm profiles will likely limit buoyancy, despite dewpoints in the mid to upper 60s. However, strong heating into the 80s and 90s F and steep low-level lapse rates combined with modest westerly flow aloft and frontal forcing may be sufficient for isolated strong storms capable of locally gusty/damaging winds this afternoon. Locally higher probability for damaging gusts appears to exist across southern ME, where greater deep-layer shear is presence, and over the northern Mid-Atlantic where dewpoints and buoyancy will be highest. ..Mosier/Grams.. 08/17/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Sun Aug 17 2025 Valid 171630Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE MIDDLE MISSOURI VALLEY VICINITY... ...SUMMARY... One or two clusters of thunderstorms may develop and gradually pose a risk for damaging wind gusts from the northern High Plains into the Midwest this afternoon and tonight. Damaging thunderstorm wind gusts may also occur across parts of the northern Mid Atlantic into southern New England late this afternoon and evening. ...Northern/Central Plains into Upper Midwest... The combination of close proximity to the upper ridge that covers much of the central/southern CONUS, lack of more defined synoptic features, and ample low-level moisture and buoyancy yields a complex and uncertain forecast from the northern/central Plains into the Midwest today and tonight. Recent satellite and radar imagery depicts two MCVs across the region, one over central SD and the other across central NE. Surface analysis also shows a low over the central SD/NE border, along the northern periphery of the NE MCV. A mix of convective outflow, cloud cover, and a formally more defined surface boundary has resulted in a warm-front-like feature extending southeastward from this surface low through central IA. All of these features will likely play a role in thunderstorm development today. The general expectation is for mesoscale ascent attendant to the surface low and MCV to yield increasing thunderstorm development across southeast SD and northeast NE over the next few hours. A sharpening warm front will likely shift northward, providing a favored corridor for storm progression, with the ongoing storms continuing downstream along this corridor into southwest MN and northwest/north-central IA. Damaging gusts will be the primary risk, with severe coverage expected to become high enough to merit introducing 15% wind probabilities. A more stable airmass to the north/northeast of the boundary should limit the severe risk over central MN and central WI. Much of the guidance also shows evening thunderstorm development beginning in eastern WY/southwest SD/NE Panhandle region before then spreading eastward/southeastward with time. This activity appears to be initially associated with low-level convergence along the lee troughing, with its progression southeastward likely tied to an increasing low-level jet. Isolated hail is possible initially with a few stronger gusts then possible overnight. ...Northern Rockies/northern High Plains... Scattered high-based thunderstorms are expected this afternoon and evening as ascent attendant the shortwave trough currently moving through eastern OR spreads into the region. Combination of moderate mid-level southwesterly flow, steep low-level lapse rates, and high cloud bases could contribute to isolated strong to severe gusts within these storms as they gradually move from southwest MT into central/southeastern MT. ...Mid Atlantic into southern New England... Recent surface analysis places a cold front from northern ME southwestward through western NY and northwest PA in northern OH. Mid-level lapse rates are weak, and the relatively warm profiles will likely limit buoyancy, despite dewpoints in the mid to upper 60s. However, strong heating into the 80s and 90s F and steep low-level lapse rates combined with modest westerly flow aloft and frontal forcing may be sufficient for isolated strong storms capable of locally gusty/damaging winds this afternoon. Locally higher probability for damaging gusts appears to exist across southern ME, where greater deep-layer shear is presence, and over the northern Mid-Atlantic where dewpoints and buoyancy will be highest. ..Mosier/Grams.. 08/17/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Sun Aug 17 2025 Valid 171630Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE MIDDLE MISSOURI VALLEY VICINITY... ...SUMMARY... One or two clusters of thunderstorms may develop and gradually pose a risk for damaging wind gusts from the northern High Plains into the Midwest this afternoon and tonight. Damaging thunderstorm wind gusts may also occur across parts of the northern Mid Atlantic into southern New England late this afternoon and evening. ...Northern/Central Plains into Upper Midwest... The combination of close proximity to the upper ridge that covers much of the central/southern CONUS, lack of more defined synoptic features, and ample low-level moisture and buoyancy yields a complex and uncertain forecast from the northern/central Plains into the Midwest today and tonight. Recent satellite and radar imagery depicts two MCVs across the region, one over central SD and the other across central NE. Surface analysis also shows a low over the central SD/NE border, along the northern periphery of the NE MCV. A mix of convective outflow, cloud cover, and a formally more defined surface boundary has resulted in a warm-front-like feature extending southeastward from this surface low through central IA. All of these features will likely play a role in thunderstorm development today. The general expectation is for mesoscale ascent attendant to the surface low and MCV to yield increasing thunderstorm development across southeast SD and northeast NE over the next few hours. A sharpening warm front will likely shift northward, providing a favored corridor for storm progression, with the ongoing storms continuing downstream along this corridor into southwest MN and northwest/north-central IA. Damaging gusts will be the primary risk, with severe coverage expected to become high enough to merit introducing 15% wind probabilities. A more stable airmass to the north/northeast of the boundary should limit the severe risk over central MN and central WI. Much of the guidance also shows evening thunderstorm development beginning in eastern WY/southwest SD/NE Panhandle region before then spreading eastward/southeastward with time. This activity appears to be initially associated with low-level convergence along the lee troughing, with its progression southeastward likely tied to an increasing low-level jet. Isolated hail is possible initially with a few stronger gusts then possible overnight. ...Northern Rockies/northern High Plains... Scattered high-based thunderstorms are expected this afternoon and evening as ascent attendant the shortwave trough currently moving through eastern OR spreads into the region. Combination of moderate mid-level southwesterly flow, steep low-level lapse rates, and high cloud bases could contribute to isolated strong to severe gusts within these storms as they gradually move from southwest MT into central/southeastern MT. ...Mid Atlantic into southern New England... Recent surface analysis places a cold front from northern ME southwestward through western NY and northwest PA in northern OH. Mid-level lapse rates are weak, and the relatively warm profiles will likely limit buoyancy, despite dewpoints in the mid to upper 60s. However, strong heating into the 80s and 90s F and steep low-level lapse rates combined with modest westerly flow aloft and frontal forcing may be sufficient for isolated strong storms capable of locally gusty/damaging winds this afternoon. Locally higher probability for damaging gusts appears to exist across southern ME, where greater deep-layer shear is presence, and over the northern Mid-Atlantic where dewpoints and buoyancy will be highest. ..Mosier/Grams.. 08/17/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Sun Aug 17 2025 Valid 171630Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE MIDDLE MISSOURI VALLEY VICINITY... ...SUMMARY... One or two clusters of thunderstorms may develop and gradually pose a risk for damaging wind gusts from the northern High Plains into the Midwest this afternoon and tonight. Damaging thunderstorm wind gusts may also occur across parts of the northern Mid Atlantic into southern New England late this afternoon and evening. ...Northern/Central Plains into Upper Midwest... The combination of close proximity to the upper ridge that covers much of the central/southern CONUS, lack of more defined synoptic features, and ample low-level moisture and buoyancy yields a complex and uncertain forecast from the northern/central Plains into the Midwest today and tonight. Recent satellite and radar imagery depicts two MCVs across the region, one over central SD and the other across central NE. Surface analysis also shows a low over the central SD/NE border, along the northern periphery of the NE MCV. A mix of convective outflow, cloud cover, and a formally more defined surface boundary has resulted in a warm-front-like feature extending southeastward from this surface low through central IA. All of these features will likely play a role in thunderstorm development today. The general expectation is for mesoscale ascent attendant to the surface low and MCV to yield increasing thunderstorm development across southeast SD and northeast NE over the next few hours. A sharpening warm front will likely shift northward, providing a favored corridor for storm progression, with the ongoing storms continuing downstream along this corridor into southwest MN and northwest/north-central IA. Damaging gusts will be the primary risk, with severe coverage expected to become high enough to merit introducing 15% wind probabilities. A more stable airmass to the north/northeast of the boundary should limit the severe risk over central MN and central WI. Much of the guidance also shows evening thunderstorm development beginning in eastern WY/southwest SD/NE Panhandle region before then spreading eastward/southeastward with time. This activity appears to be initially associated with low-level convergence along the lee troughing, with its progression southeastward likely tied to an increasing low-level jet. Isolated hail is possible initially with a few stronger gusts then possible overnight. ...Northern Rockies/northern High Plains... Scattered high-based thunderstorms are expected this afternoon and evening as ascent attendant the shortwave trough currently moving through eastern OR spreads into the region. Combination of moderate mid-level southwesterly flow, steep low-level lapse rates, and high cloud bases could contribute to isolated strong to severe gusts within these storms as they gradually move from southwest MT into central/southeastern MT. ...Mid Atlantic into southern New England... Recent surface analysis places a cold front from northern ME southwestward through western NY and northwest PA in northern OH. Mid-level lapse rates are weak, and the relatively warm profiles will likely limit buoyancy, despite dewpoints in the mid to upper 60s. However, strong heating into the 80s and 90s F and steep low-level lapse rates combined with modest westerly flow aloft and frontal forcing may be sufficient for isolated strong storms capable of locally gusty/damaging winds this afternoon. Locally higher probability for damaging gusts appears to exist across southern ME, where greater deep-layer shear is presence, and over the northern Mid-Atlantic where dewpoints and buoyancy will be highest. ..Mosier/Grams.. 08/17/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Sun Aug 17 2025 Valid 171630Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE MIDDLE MISSOURI VALLEY VICINITY... ...SUMMARY... One or two clusters of thunderstorms may develop and gradually pose a risk for damaging wind gusts from the northern High Plains into the Midwest this afternoon and tonight. Damaging thunderstorm wind gusts may also occur across parts of the northern Mid Atlantic into southern New England late this afternoon and evening. ...Northern/Central Plains into Upper Midwest... The combination of close proximity to the upper ridge that covers much of the central/southern CONUS, lack of more defined synoptic features, and ample low-level moisture and buoyancy yields a complex and uncertain forecast from the northern/central Plains into the Midwest today and tonight. Recent satellite and radar imagery depicts two MCVs across the region, one over central SD and the other across central NE. Surface analysis also shows a low over the central SD/NE border, along the northern periphery of the NE MCV. A mix of convective outflow, cloud cover, and a formally more defined surface boundary has resulted in a warm-front-like feature extending southeastward from this surface low through central IA. All of these features will likely play a role in thunderstorm development today. The general expectation is for mesoscale ascent attendant to the surface low and MCV to yield increasing thunderstorm development across southeast SD and northeast NE over the next few hours. A sharpening warm front will likely shift northward, providing a favored corridor for storm progression, with the ongoing storms continuing downstream along this corridor into southwest MN and northwest/north-central IA. Damaging gusts will be the primary risk, with severe coverage expected to become high enough to merit introducing 15% wind probabilities. A more stable airmass to the north/northeast of the boundary should limit the severe risk over central MN and central WI. Much of the guidance also shows evening thunderstorm development beginning in eastern WY/southwest SD/NE Panhandle region before then spreading eastward/southeastward with time. This activity appears to be initially associated with low-level convergence along the lee troughing, with its progression southeastward likely tied to an increasing low-level jet. Isolated hail is possible initially with a few stronger gusts then possible overnight. ...Northern Rockies/northern High Plains... Scattered high-based thunderstorms are expected this afternoon and evening as ascent attendant the shortwave trough currently moving through eastern OR spreads into the region. Combination of moderate mid-level southwesterly flow, steep low-level lapse rates, and high cloud bases could contribute to isolated strong to severe gusts within these storms as they gradually move from southwest MT into central/southeastern MT. ...Mid Atlantic into southern New England... Recent surface analysis places a cold front from northern ME southwestward through western NY and northwest PA in northern OH. Mid-level lapse rates are weak, and the relatively warm profiles will likely limit buoyancy, despite dewpoints in the mid to upper 60s. However, strong heating into the 80s and 90s F and steep low-level lapse rates combined with modest westerly flow aloft and frontal forcing may be sufficient for isolated strong storms capable of locally gusty/damaging winds this afternoon. Locally higher probability for damaging gusts appears to exist across southern ME, where greater deep-layer shear is presence, and over the northern Mid-Atlantic where dewpoints and buoyancy will be highest. ..Mosier/Grams.. 08/17/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Sun Aug 17 2025 Valid 171630Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE MIDDLE MISSOURI VALLEY VICINITY... ...SUMMARY... One or two clusters of thunderstorms may develop and gradually pose a risk for damaging wind gusts from the northern High Plains into the Midwest this afternoon and tonight. Damaging thunderstorm wind gusts may also occur across parts of the northern Mid Atlantic into southern New England late this afternoon and evening. ...Northern/Central Plains into Upper Midwest... The combination of close proximity to the upper ridge that covers much of the central/southern CONUS, lack of more defined synoptic features, and ample low-level moisture and buoyancy yields a complex and uncertain forecast from the northern/central Plains into the Midwest today and tonight. Recent satellite and radar imagery depicts two MCVs across the region, one over central SD and the other across central NE. Surface analysis also shows a low over the central SD/NE border, along the northern periphery of the NE MCV. A mix of convective outflow, cloud cover, and a formally more defined surface boundary has resulted in a warm-front-like feature extending southeastward from this surface low through central IA. All of these features will likely play a role in thunderstorm development today. The general expectation is for mesoscale ascent attendant to the surface low and MCV to yield increasing thunderstorm development across southeast SD and northeast NE over the next few hours. A sharpening warm front will likely shift northward, providing a favored corridor for storm progression, with the ongoing storms continuing downstream along this corridor into southwest MN and northwest/north-central IA. Damaging gusts will be the primary risk, with severe coverage expected to become high enough to merit introducing 15% wind probabilities. A more stable airmass to the north/northeast of the boundary should limit the severe risk over central MN and central WI. Much of the guidance also shows evening thunderstorm development beginning in eastern WY/southwest SD/NE Panhandle region before then spreading eastward/southeastward with time. This activity appears to be initially associated with low-level convergence along the lee troughing, with its progression southeastward likely tied to an increasing low-level jet. Isolated hail is possible initially with a few stronger gusts then possible overnight. ...Northern Rockies/northern High Plains... Scattered high-based thunderstorms are expected this afternoon and evening as ascent attendant the shortwave trough currently moving through eastern OR spreads into the region. Combination of moderate mid-level southwesterly flow, steep low-level lapse rates, and high cloud bases could contribute to isolated strong to severe gusts within these storms as they gradually move from southwest MT into central/southeastern MT. ...Mid Atlantic into southern New England... Recent surface analysis places a cold front from northern ME southwestward through western NY and northwest PA in northern OH. Mid-level lapse rates are weak, and the relatively warm profiles will likely limit buoyancy, despite dewpoints in the mid to upper 60s. However, strong heating into the 80s and 90s F and steep low-level lapse rates combined with modest westerly flow aloft and frontal forcing may be sufficient for isolated strong storms capable of locally gusty/damaging winds this afternoon. Locally higher probability for damaging gusts appears to exist across southern ME, where greater deep-layer shear is presence, and over the northern Mid-Atlantic where dewpoints and buoyancy will be highest. ..Mosier/Grams.. 08/17/2025 Read more