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SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0301 PM CDT Sun Aug 17 2025 Valid 172000Z - 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. ...20Z Update... Preceding a remnant MCV tracking northeastward across parts of southeastern SD, an elevated cluster of thunderstorms is spreading northeastward from east-central SD into southwest MN. Ahead of this activity, earlier stable/billow clouds have eroded along/north of a surface boundary draped across southwestern MN, where diurnal heating amid lower 70s dewpoints is contributing to gradual air mass recovery/destabilization. Given this continued destabilization, the Slight Risk was expanded slightly northward, and was also trimmed on the western edge in the wake of the MCV. Farther east, the Marginal Risk was expanded slightly westward into northeastern WV -- ahead of an ongoing cluster of thunderstorms with a history of wind damage. See MCD 1975 for more details. For details on the near-term severe threat over the Black Hills vicinity, reference MCD 1976. ..Weinman.. 08/17/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Aug 17 2025/ ...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. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0301 PM CDT Sun Aug 17 2025 Valid 172000Z - 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. ...20Z Update... Preceding a remnant MCV tracking northeastward across parts of southeastern SD, an elevated cluster of thunderstorms is spreading northeastward from east-central SD into southwest MN. Ahead of this activity, earlier stable/billow clouds have eroded along/north of a surface boundary draped across southwestern MN, where diurnal heating amid lower 70s dewpoints is contributing to gradual air mass recovery/destabilization. Given this continued destabilization, the Slight Risk was expanded slightly northward, and was also trimmed on the western edge in the wake of the MCV. Farther east, the Marginal Risk was expanded slightly westward into northeastern WV -- ahead of an ongoing cluster of thunderstorms with a history of wind damage. See MCD 1975 for more details. For details on the near-term severe threat over the Black Hills vicinity, reference MCD 1976. ..Weinman.. 08/17/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Aug 17 2025/ ...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. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0301 PM CDT Sun Aug 17 2025 Valid 172000Z - 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. ...20Z Update... Preceding a remnant MCV tracking northeastward across parts of southeastern SD, an elevated cluster of thunderstorms is spreading northeastward from east-central SD into southwest MN. Ahead of this activity, earlier stable/billow clouds have eroded along/north of a surface boundary draped across southwestern MN, where diurnal heating amid lower 70s dewpoints is contributing to gradual air mass recovery/destabilization. Given this continued destabilization, the Slight Risk was expanded slightly northward, and was also trimmed on the western edge in the wake of the MCV. Farther east, the Marginal Risk was expanded slightly westward into northeastern WV -- ahead of an ongoing cluster of thunderstorms with a history of wind damage. See MCD 1975 for more details. For details on the near-term severe threat over the Black Hills vicinity, reference MCD 1976. ..Weinman.. 08/17/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Aug 17 2025/ ...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. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0301 PM CDT Sun Aug 17 2025 Valid 172000Z - 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. ...20Z Update... Preceding a remnant MCV tracking northeastward across parts of southeastern SD, an elevated cluster of thunderstorms is spreading northeastward from east-central SD into southwest MN. Ahead of this activity, earlier stable/billow clouds have eroded along/north of a surface boundary draped across southwestern MN, where diurnal heating amid lower 70s dewpoints is contributing to gradual air mass recovery/destabilization. Given this continued destabilization, the Slight Risk was expanded slightly northward, and was also trimmed on the western edge in the wake of the MCV. Farther east, the Marginal Risk was expanded slightly westward into northeastern WV -- ahead of an ongoing cluster of thunderstorms with a history of wind damage. See MCD 1975 for more details. For details on the near-term severe threat over the Black Hills vicinity, reference MCD 1976. ..Weinman.. 08/17/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Aug 17 2025/ ...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. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0301 PM CDT Sun Aug 17 2025 Valid 172000Z - 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. ...20Z Update... Preceding a remnant MCV tracking northeastward across parts of southeastern SD, an elevated cluster of thunderstorms is spreading northeastward from east-central SD into southwest MN. Ahead of this activity, earlier stable/billow clouds have eroded along/north of a surface boundary draped across southwestern MN, where diurnal heating amid lower 70s dewpoints is contributing to gradual air mass recovery/destabilization. Given this continued destabilization, the Slight Risk was expanded slightly northward, and was also trimmed on the western edge in the wake of the MCV. Farther east, the Marginal Risk was expanded slightly westward into northeastern WV -- ahead of an ongoing cluster of thunderstorms with a history of wind damage. See MCD 1975 for more details. For details on the near-term severe threat over the Black Hills vicinity, reference MCD 1976. ..Weinman.. 08/17/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Aug 17 2025/ ...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. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0301 PM CDT Sun Aug 17 2025 Valid 172000Z - 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. ...20Z Update... Preceding a remnant MCV tracking northeastward across parts of southeastern SD, an elevated cluster of thunderstorms is spreading northeastward from east-central SD into southwest MN. Ahead of this activity, earlier stable/billow clouds have eroded along/north of a surface boundary draped across southwestern MN, where diurnal heating amid lower 70s dewpoints is contributing to gradual air mass recovery/destabilization. Given this continued destabilization, the Slight Risk was expanded slightly northward, and was also trimmed on the western edge in the wake of the MCV. Farther east, the Marginal Risk was expanded slightly westward into northeastern WV -- ahead of an ongoing cluster of thunderstorms with a history of wind damage. See MCD 1975 for more details. For details on the near-term severe threat over the Black Hills vicinity, reference MCD 1976. ..Weinman.. 08/17/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Aug 17 2025/ ...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. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0301 PM CDT Sun Aug 17 2025 Valid 172000Z - 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. ...20Z Update... Preceding a remnant MCV tracking northeastward across parts of southeastern SD, an elevated cluster of thunderstorms is spreading northeastward from east-central SD into southwest MN. Ahead of this activity, earlier stable/billow clouds have eroded along/north of a surface boundary draped across southwestern MN, where diurnal heating amid lower 70s dewpoints is contributing to gradual air mass recovery/destabilization. Given this continued destabilization, the Slight Risk was expanded slightly northward, and was also trimmed on the western edge in the wake of the MCV. Farther east, the Marginal Risk was expanded slightly westward into northeastern WV -- ahead of an ongoing cluster of thunderstorms with a history of wind damage. See MCD 1975 for more details. For details on the near-term severe threat over the Black Hills vicinity, reference MCD 1976. ..Weinman.. 08/17/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Aug 17 2025/ ...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. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0242 PM CDT Sun Aug 17 2025 Valid 181200Z - 191200Z ...NO CRITICAL AREAS... ...Northern Rockies/Central Idaho Mountains... A mid-level trough over the Pacific Northwest, residual Pacific/monsoon moisture and daytime heating will result in isolated showers and thunderstorms across northern ID and higher terrain of western MT. Although northeast thunderstorm motions of 25-30 knots will limit rainfall, fuels remain mostly non-receptive to new lightning ignitions across the Northern Rockies, precluding introduction of dry thunderstorm highlights for Monday. ...Great Basin... Modest south-southwest deep layer flow and efficient daytime mixing of a deep/dry boundary layer will support sustained south-southwest winds of 10-15 mph across southern/northern NV Monday afternoon, mainly in longitudinal oriented valleys. Winds combined with relative humidity nearing 10 percent will support short duration and localized elevated fire weather conditions across southern, central and northeastern NV where very dry fuels exist. ..Williams.. 08/17/2025 .PREV DISCUSSION... /ISSUED 0201 AM CDT Sun Aug 17 2025/ ...Synopsis... Mid-level ridging will rapidly build over the central and western US Monday as Northwest troughing continues. Above normal temperatures are expected along with a temporary decrease in monsoon moisture over much of the West. While the ridge expands, the majority of the stronger westerly flow will be shunted northward, poorly overlapping with the expected dry conditions. With weaker flow aloft, surface winds are expected to be relatively benign, limiting fire-weather potential. Still, very hot and dry conditions are expected, which could exacerbate ongoing fires locally. Additionally, a few thunderstorms remain possible over parts of eastern ID and western MT near the periphery of the ridge. While some dry lightning strikes are possible in receptive fuels, wetting rainfall and the more limited storm coverage appear unlikely to warrant 10% IsoDryT coverage. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0242 PM CDT Sun Aug 17 2025 Valid 181200Z - 191200Z ...NO CRITICAL AREAS... ...Northern Rockies/Central Idaho Mountains... A mid-level trough over the Pacific Northwest, residual Pacific/monsoon moisture and daytime heating will result in isolated showers and thunderstorms across northern ID and higher terrain of western MT. Although northeast thunderstorm motions of 25-30 knots will limit rainfall, fuels remain mostly non-receptive to new lightning ignitions across the Northern Rockies, precluding introduction of dry thunderstorm highlights for Monday. ...Great Basin... Modest south-southwest deep layer flow and efficient daytime mixing of a deep/dry boundary layer will support sustained south-southwest winds of 10-15 mph across southern/northern NV Monday afternoon, mainly in longitudinal oriented valleys. Winds combined with relative humidity nearing 10 percent will support short duration and localized elevated fire weather conditions across southern, central and northeastern NV where very dry fuels exist. ..Williams.. 08/17/2025 .PREV DISCUSSION... /ISSUED 0201 AM CDT Sun Aug 17 2025/ ...Synopsis... Mid-level ridging will rapidly build over the central and western US Monday as Northwest troughing continues. Above normal temperatures are expected along with a temporary decrease in monsoon moisture over much of the West. While the ridge expands, the majority of the stronger westerly flow will be shunted northward, poorly overlapping with the expected dry conditions. With weaker flow aloft, surface winds are expected to be relatively benign, limiting fire-weather potential. Still, very hot and dry conditions are expected, which could exacerbate ongoing fires locally. Additionally, a few thunderstorms remain possible over parts of eastern ID and western MT near the periphery of the ridge. While some dry lightning strikes are possible in receptive fuels, wetting rainfall and the more limited storm coverage appear unlikely to warrant 10% IsoDryT coverage. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0242 PM CDT Sun Aug 17 2025 Valid 181200Z - 191200Z ...NO CRITICAL AREAS... ...Northern Rockies/Central Idaho Mountains... A mid-level trough over the Pacific Northwest, residual Pacific/monsoon moisture and daytime heating will result in isolated showers and thunderstorms across northern ID and higher terrain of western MT. Although northeast thunderstorm motions of 25-30 knots will limit rainfall, fuels remain mostly non-receptive to new lightning ignitions across the Northern Rockies, precluding introduction of dry thunderstorm highlights for Monday. ...Great Basin... Modest south-southwest deep layer flow and efficient daytime mixing of a deep/dry boundary layer will support sustained south-southwest winds of 10-15 mph across southern/northern NV Monday afternoon, mainly in longitudinal oriented valleys. Winds combined with relative humidity nearing 10 percent will support short duration and localized elevated fire weather conditions across southern, central and northeastern NV where very dry fuels exist. ..Williams.. 08/17/2025 .PREV DISCUSSION... /ISSUED 0201 AM CDT Sun Aug 17 2025/ ...Synopsis... Mid-level ridging will rapidly build over the central and western US Monday as Northwest troughing continues. Above normal temperatures are expected along with a temporary decrease in monsoon moisture over much of the West. While the ridge expands, the majority of the stronger westerly flow will be shunted northward, poorly overlapping with the expected dry conditions. With weaker flow aloft, surface winds are expected to be relatively benign, limiting fire-weather potential. Still, very hot and dry conditions are expected, which could exacerbate ongoing fires locally. Additionally, a few thunderstorms remain possible over parts of eastern ID and western MT near the periphery of the ridge. While some dry lightning strikes are possible in receptive fuels, wetting rainfall and the more limited storm coverage appear unlikely to warrant 10% IsoDryT coverage. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0242 PM CDT Sun Aug 17 2025 Valid 181200Z - 191200Z ...NO CRITICAL AREAS... ...Northern Rockies/Central Idaho Mountains... A mid-level trough over the Pacific Northwest, residual Pacific/monsoon moisture and daytime heating will result in isolated showers and thunderstorms across northern ID and higher terrain of western MT. Although northeast thunderstorm motions of 25-30 knots will limit rainfall, fuels remain mostly non-receptive to new lightning ignitions across the Northern Rockies, precluding introduction of dry thunderstorm highlights for Monday. ...Great Basin... Modest south-southwest deep layer flow and efficient daytime mixing of a deep/dry boundary layer will support sustained south-southwest winds of 10-15 mph across southern/northern NV Monday afternoon, mainly in longitudinal oriented valleys. Winds combined with relative humidity nearing 10 percent will support short duration and localized elevated fire weather conditions across southern, central and northeastern NV where very dry fuels exist. ..Williams.. 08/17/2025 .PREV DISCUSSION... /ISSUED 0201 AM CDT Sun Aug 17 2025/ ...Synopsis... Mid-level ridging will rapidly build over the central and western US Monday as Northwest troughing continues. Above normal temperatures are expected along with a temporary decrease in monsoon moisture over much of the West. While the ridge expands, the majority of the stronger westerly flow will be shunted northward, poorly overlapping with the expected dry conditions. With weaker flow aloft, surface winds are expected to be relatively benign, limiting fire-weather potential. Still, very hot and dry conditions are expected, which could exacerbate ongoing fires locally. Additionally, a few thunderstorms remain possible over parts of eastern ID and western MT near the periphery of the ridge. While some dry lightning strikes are possible in receptive fuels, wetting rainfall and the more limited storm coverage appear unlikely to warrant 10% IsoDryT coverage. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0242 PM CDT Sun Aug 17 2025 Valid 181200Z - 191200Z ...NO CRITICAL AREAS... ...Northern Rockies/Central Idaho Mountains... A mid-level trough over the Pacific Northwest, residual Pacific/monsoon moisture and daytime heating will result in isolated showers and thunderstorms across northern ID and higher terrain of western MT. Although northeast thunderstorm motions of 25-30 knots will limit rainfall, fuels remain mostly non-receptive to new lightning ignitions across the Northern Rockies, precluding introduction of dry thunderstorm highlights for Monday. ...Great Basin... Modest south-southwest deep layer flow and efficient daytime mixing of a deep/dry boundary layer will support sustained south-southwest winds of 10-15 mph across southern/northern NV Monday afternoon, mainly in longitudinal oriented valleys. Winds combined with relative humidity nearing 10 percent will support short duration and localized elevated fire weather conditions across southern, central and northeastern NV where very dry fuels exist. ..Williams.. 08/17/2025 .PREV DISCUSSION... /ISSUED 0201 AM CDT Sun Aug 17 2025/ ...Synopsis... Mid-level ridging will rapidly build over the central and western US Monday as Northwest troughing continues. Above normal temperatures are expected along with a temporary decrease in monsoon moisture over much of the West. While the ridge expands, the majority of the stronger westerly flow will be shunted northward, poorly overlapping with the expected dry conditions. With weaker flow aloft, surface winds are expected to be relatively benign, limiting fire-weather potential. Still, very hot and dry conditions are expected, which could exacerbate ongoing fires locally. Additionally, a few thunderstorms remain possible over parts of eastern ID and western MT near the periphery of the ridge. While some dry lightning strikes are possible in receptive fuels, wetting rainfall and the more limited storm coverage appear unlikely to warrant 10% IsoDryT coverage. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0242 PM CDT Sun Aug 17 2025 Valid 181200Z - 191200Z ...NO CRITICAL AREAS... ...Northern Rockies/Central Idaho Mountains... A mid-level trough over the Pacific Northwest, residual Pacific/monsoon moisture and daytime heating will result in isolated showers and thunderstorms across northern ID and higher terrain of western MT. Although northeast thunderstorm motions of 25-30 knots will limit rainfall, fuels remain mostly non-receptive to new lightning ignitions across the Northern Rockies, precluding introduction of dry thunderstorm highlights for Monday. ...Great Basin... Modest south-southwest deep layer flow and efficient daytime mixing of a deep/dry boundary layer will support sustained south-southwest winds of 10-15 mph across southern/northern NV Monday afternoon, mainly in longitudinal oriented valleys. Winds combined with relative humidity nearing 10 percent will support short duration and localized elevated fire weather conditions across southern, central and northeastern NV where very dry fuels exist. ..Williams.. 08/17/2025 .PREV DISCUSSION... /ISSUED 0201 AM CDT Sun Aug 17 2025/ ...Synopsis... Mid-level ridging will rapidly build over the central and western US Monday as Northwest troughing continues. Above normal temperatures are expected along with a temporary decrease in monsoon moisture over much of the West. While the ridge expands, the majority of the stronger westerly flow will be shunted northward, poorly overlapping with the expected dry conditions. With weaker flow aloft, surface winds are expected to be relatively benign, limiting fire-weather potential. Still, very hot and dry conditions are expected, which could exacerbate ongoing fires locally. Additionally, a few thunderstorms remain possible over parts of eastern ID and western MT near the periphery of the ridge. While some dry lightning strikes are possible in receptive fuels, wetting rainfall and the more limited storm coverage appear unlikely to warrant 10% IsoDryT coverage. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0242 PM CDT Sun Aug 17 2025 Valid 181200Z - 191200Z ...NO CRITICAL AREAS... ...Northern Rockies/Central Idaho Mountains... A mid-level trough over the Pacific Northwest, residual Pacific/monsoon moisture and daytime heating will result in isolated showers and thunderstorms across northern ID and higher terrain of western MT. Although northeast thunderstorm motions of 25-30 knots will limit rainfall, fuels remain mostly non-receptive to new lightning ignitions across the Northern Rockies, precluding introduction of dry thunderstorm highlights for Monday. ...Great Basin... Modest south-southwest deep layer flow and efficient daytime mixing of a deep/dry boundary layer will support sustained south-southwest winds of 10-15 mph across southern/northern NV Monday afternoon, mainly in longitudinal oriented valleys. Winds combined with relative humidity nearing 10 percent will support short duration and localized elevated fire weather conditions across southern, central and northeastern NV where very dry fuels exist. ..Williams.. 08/17/2025 .PREV DISCUSSION... /ISSUED 0201 AM CDT Sun Aug 17 2025/ ...Synopsis... Mid-level ridging will rapidly build over the central and western US Monday as Northwest troughing continues. Above normal temperatures are expected along with a temporary decrease in monsoon moisture over much of the West. While the ridge expands, the majority of the stronger westerly flow will be shunted northward, poorly overlapping with the expected dry conditions. With weaker flow aloft, surface winds are expected to be relatively benign, limiting fire-weather potential. Still, very hot and dry conditions are expected, which could exacerbate ongoing fires locally. Additionally, a few thunderstorms remain possible over parts of eastern ID and western MT near the periphery of the ridge. While some dry lightning strikes are possible in receptive fuels, wetting rainfall and the more limited storm coverage appear unlikely to warrant 10% IsoDryT coverage. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0242 PM CDT Sun Aug 17 2025 Valid 181200Z - 191200Z ...NO CRITICAL AREAS... ...Northern Rockies/Central Idaho Mountains... A mid-level trough over the Pacific Northwest, residual Pacific/monsoon moisture and daytime heating will result in isolated showers and thunderstorms across northern ID and higher terrain of western MT. Although northeast thunderstorm motions of 25-30 knots will limit rainfall, fuels remain mostly non-receptive to new lightning ignitions across the Northern Rockies, precluding introduction of dry thunderstorm highlights for Monday. ...Great Basin... Modest south-southwest deep layer flow and efficient daytime mixing of a deep/dry boundary layer will support sustained south-southwest winds of 10-15 mph across southern/northern NV Monday afternoon, mainly in longitudinal oriented valleys. Winds combined with relative humidity nearing 10 percent will support short duration and localized elevated fire weather conditions across southern, central and northeastern NV where very dry fuels exist. ..Williams.. 08/17/2025 .PREV DISCUSSION... /ISSUED 0201 AM CDT Sun Aug 17 2025/ ...Synopsis... Mid-level ridging will rapidly build over the central and western US Monday as Northwest troughing continues. Above normal temperatures are expected along with a temporary decrease in monsoon moisture over much of the West. While the ridge expands, the majority of the stronger westerly flow will be shunted northward, poorly overlapping with the expected dry conditions. With weaker flow aloft, surface winds are expected to be relatively benign, limiting fire-weather potential. Still, very hot and dry conditions are expected, which could exacerbate ongoing fires locally. Additionally, a few thunderstorms remain possible over parts of eastern ID and western MT near the periphery of the ridge. While some dry lightning strikes are possible in receptive fuels, wetting rainfall and the more limited storm coverage appear unlikely to warrant 10% IsoDryT coverage. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0242 PM CDT Sun Aug 17 2025 Valid 181200Z - 191200Z ...NO CRITICAL AREAS... ...Northern Rockies/Central Idaho Mountains... A mid-level trough over the Pacific Northwest, residual Pacific/monsoon moisture and daytime heating will result in isolated showers and thunderstorms across northern ID and higher terrain of western MT. Although northeast thunderstorm motions of 25-30 knots will limit rainfall, fuels remain mostly non-receptive to new lightning ignitions across the Northern Rockies, precluding introduction of dry thunderstorm highlights for Monday. ...Great Basin... Modest south-southwest deep layer flow and efficient daytime mixing of a deep/dry boundary layer will support sustained south-southwest winds of 10-15 mph across southern/northern NV Monday afternoon, mainly in longitudinal oriented valleys. Winds combined with relative humidity nearing 10 percent will support short duration and localized elevated fire weather conditions across southern, central and northeastern NV where very dry fuels exist. ..Williams.. 08/17/2025 .PREV DISCUSSION... /ISSUED 0201 AM CDT Sun Aug 17 2025/ ...Synopsis... Mid-level ridging will rapidly build over the central and western US Monday as Northwest troughing continues. Above normal temperatures are expected along with a temporary decrease in monsoon moisture over much of the West. While the ridge expands, the majority of the stronger westerly flow will be shunted northward, poorly overlapping with the expected dry conditions. With weaker flow aloft, surface winds are expected to be relatively benign, limiting fire-weather potential. Still, very hot and dry conditions are expected, which could exacerbate ongoing fires locally. Additionally, a few thunderstorms remain possible over parts of eastern ID and western MT near the periphery of the ridge. While some dry lightning strikes are possible in receptive fuels, wetting rainfall and the more limited storm coverage appear unlikely to warrant 10% IsoDryT coverage. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0242 PM CDT Sun Aug 17 2025 Valid 181200Z - 191200Z ...NO CRITICAL AREAS... ...Northern Rockies/Central Idaho Mountains... A mid-level trough over the Pacific Northwest, residual Pacific/monsoon moisture and daytime heating will result in isolated showers and thunderstorms across northern ID and higher terrain of western MT. Although northeast thunderstorm motions of 25-30 knots will limit rainfall, fuels remain mostly non-receptive to new lightning ignitions across the Northern Rockies, precluding introduction of dry thunderstorm highlights for Monday. ...Great Basin... Modest south-southwest deep layer flow and efficient daytime mixing of a deep/dry boundary layer will support sustained south-southwest winds of 10-15 mph across southern/northern NV Monday afternoon, mainly in longitudinal oriented valleys. Winds combined with relative humidity nearing 10 percent will support short duration and localized elevated fire weather conditions across southern, central and northeastern NV where very dry fuels exist. ..Williams.. 08/17/2025 .PREV DISCUSSION... /ISSUED 0201 AM CDT Sun Aug 17 2025/ ...Synopsis... Mid-level ridging will rapidly build over the central and western US Monday as Northwest troughing continues. Above normal temperatures are expected along with a temporary decrease in monsoon moisture over much of the West. While the ridge expands, the majority of the stronger westerly flow will be shunted northward, poorly overlapping with the expected dry conditions. With weaker flow aloft, surface winds are expected to be relatively benign, limiting fire-weather potential. Still, very hot and dry conditions are expected, which could exacerbate ongoing fires locally. Additionally, a few thunderstorms remain possible over parts of eastern ID and western MT near the periphery of the ridge. While some dry lightning strikes are possible in receptive fuels, wetting rainfall and the more limited storm coverage appear unlikely to warrant 10% IsoDryT coverage. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0242 PM CDT Sun Aug 17 2025 Valid 181200Z - 191200Z ...NO CRITICAL AREAS... ...Northern Rockies/Central Idaho Mountains... A mid-level trough over the Pacific Northwest, residual Pacific/monsoon moisture and daytime heating will result in isolated showers and thunderstorms across northern ID and higher terrain of western MT. Although northeast thunderstorm motions of 25-30 knots will limit rainfall, fuels remain mostly non-receptive to new lightning ignitions across the Northern Rockies, precluding introduction of dry thunderstorm highlights for Monday. ...Great Basin... Modest south-southwest deep layer flow and efficient daytime mixing of a deep/dry boundary layer will support sustained south-southwest winds of 10-15 mph across southern/northern NV Monday afternoon, mainly in longitudinal oriented valleys. Winds combined with relative humidity nearing 10 percent will support short duration and localized elevated fire weather conditions across southern, central and northeastern NV where very dry fuels exist. ..Williams.. 08/17/2025 .PREV DISCUSSION... /ISSUED 0201 AM CDT Sun Aug 17 2025/ ...Synopsis... Mid-level ridging will rapidly build over the central and western US Monday as Northwest troughing continues. Above normal temperatures are expected along with a temporary decrease in monsoon moisture over much of the West. While the ridge expands, the majority of the stronger westerly flow will be shunted northward, poorly overlapping with the expected dry conditions. With weaker flow aloft, surface winds are expected to be relatively benign, limiting fire-weather potential. Still, very hot and dry conditions are expected, which could exacerbate ongoing fires locally. Additionally, a few thunderstorms remain possible over parts of eastern ID and western MT near the periphery of the ridge. While some dry lightning strikes are possible in receptive fuels, wetting rainfall and the more limited storm coverage appear unlikely to warrant 10% IsoDryT coverage. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0242 PM CDT Sun Aug 17 2025 Valid 181200Z - 191200Z ...NO CRITICAL AREAS... ...Northern Rockies/Central Idaho Mountains... A mid-level trough over the Pacific Northwest, residual Pacific/monsoon moisture and daytime heating will result in isolated showers and thunderstorms across northern ID and higher terrain of western MT. Although northeast thunderstorm motions of 25-30 knots will limit rainfall, fuels remain mostly non-receptive to new lightning ignitions across the Northern Rockies, precluding introduction of dry thunderstorm highlights for Monday. ...Great Basin... Modest south-southwest deep layer flow and efficient daytime mixing of a deep/dry boundary layer will support sustained south-southwest winds of 10-15 mph across southern/northern NV Monday afternoon, mainly in longitudinal oriented valleys. Winds combined with relative humidity nearing 10 percent will support short duration and localized elevated fire weather conditions across southern, central and northeastern NV where very dry fuels exist. ..Williams.. 08/17/2025 .PREV DISCUSSION... /ISSUED 0201 AM CDT Sun Aug 17 2025/ ...Synopsis... Mid-level ridging will rapidly build over the central and western US Monday as Northwest troughing continues. Above normal temperatures are expected along with a temporary decrease in monsoon moisture over much of the West. While the ridge expands, the majority of the stronger westerly flow will be shunted northward, poorly overlapping with the expected dry conditions. With weaker flow aloft, surface winds are expected to be relatively benign, limiting fire-weather potential. Still, very hot and dry conditions are expected, which could exacerbate ongoing fires locally. Additionally, a few thunderstorms remain possible over parts of eastern ID and western MT near the periphery of the ridge. While some dry lightning strikes are possible in receptive fuels, wetting rainfall and the more limited storm coverage appear unlikely to warrant 10% IsoDryT coverage. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0227 PM CDT Sun Aug 17 2025 Valid 191200Z - 201200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Potential for organized severe weather is expected to remain low on Tuesday. ...Synopsis... The upper-level ridge will continue to amplify across the Rockies and into parts of the Plains on Tuesday. A low amplitude trough will persist in the lower Great Lakes and Northeast. At the surface, a cold front will continue southward through the central Plains into the southern Plains. Moderate to strong buoyancy will likely develop to the south and west of the surface boundary. However, mid-level flow and effective shear will be rather weak. In general, given weak overall forcing, isolated to widely scattered storms are expected. Some of these storms could be stronger and produce strong wind gusts. Predictability of where this will occur is too low to warrant severe probabilities. Modestly moist upslope flow into the Front Range could promote isolated storm development. Shear should be somewhat stronger in eastern Colorado. Confidence in storm coverage (given the intensifying ridge aloft) and storms being able to move off the terrain remains low, however. ..Wendt.. 08/17/2025 Read more