Severe Storms

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1257 AM CDT Thu Jul 17 2025 Valid 171200Z - 181200Z ...Synopsis... A shortwave trough will glance the Pacific Northwest bringing an increase of westerly flow aloft across the Cascades into the Cascade Gaps. As a result, areas of increased westerly downslope flow can be expected along and just east of the Cascades in the Columbia River Basin. Sustained winds 10-15 mph (locally higher in the Cascade Gaps) overlap with afternoon relative humidity reductions to around 10-20 percent. An Elevated delineation was added with this outlook to support this potential. ...Dry Thunderstorms... A closed low off the coast of Baja California will bring moisture northward across portions of the Southwest into the Great Basin. On the fringe of this deeper moisture, isolated dry thunderstorm potential will continue across portions of western Colorado into western Wyoming, Utah, far southern Idaho and eastern Nevada. Here precipitable water values drop to around 0.50" or less with more limited coverage. Some mix of wet/dry thunderstorms will be possible in central Utah and west-central Colorado but storm motions around 15-20 kts will likely yield little measurable precipitation. ..Thornton.. 07/17/2025 ...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 1257 AM CDT Thu Jul 17 2025 Valid 171200Z - 181200Z ...Synopsis... A shortwave trough will glance the Pacific Northwest bringing an increase of westerly flow aloft across the Cascades into the Cascade Gaps. As a result, areas of increased westerly downslope flow can be expected along and just east of the Cascades in the Columbia River Basin. Sustained winds 10-15 mph (locally higher in the Cascade Gaps) overlap with afternoon relative humidity reductions to around 10-20 percent. An Elevated delineation was added with this outlook to support this potential. ...Dry Thunderstorms... A closed low off the coast of Baja California will bring moisture northward across portions of the Southwest into the Great Basin. On the fringe of this deeper moisture, isolated dry thunderstorm potential will continue across portions of western Colorado into western Wyoming, Utah, far southern Idaho and eastern Nevada. Here precipitable water values drop to around 0.50" or less with more limited coverage. Some mix of wet/dry thunderstorms will be possible in central Utah and west-central Colorado but storm motions around 15-20 kts will likely yield little measurable precipitation. ..Thornton.. 07/17/2025 ...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 1257 AM CDT Thu Jul 17 2025 Valid 171200Z - 181200Z ...Synopsis... A shortwave trough will glance the Pacific Northwest bringing an increase of westerly flow aloft across the Cascades into the Cascade Gaps. As a result, areas of increased westerly downslope flow can be expected along and just east of the Cascades in the Columbia River Basin. Sustained winds 10-15 mph (locally higher in the Cascade Gaps) overlap with afternoon relative humidity reductions to around 10-20 percent. An Elevated delineation was added with this outlook to support this potential. ...Dry Thunderstorms... A closed low off the coast of Baja California will bring moisture northward across portions of the Southwest into the Great Basin. On the fringe of this deeper moisture, isolated dry thunderstorm potential will continue across portions of western Colorado into western Wyoming, Utah, far southern Idaho and eastern Nevada. Here precipitable water values drop to around 0.50" or less with more limited coverage. Some mix of wet/dry thunderstorms will be possible in central Utah and west-central Colorado but storm motions around 15-20 kts will likely yield little measurable precipitation. ..Thornton.. 07/17/2025 ...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 1257 AM CDT Thu Jul 17 2025 Valid 171200Z - 181200Z ...Synopsis... A shortwave trough will glance the Pacific Northwest bringing an increase of westerly flow aloft across the Cascades into the Cascade Gaps. As a result, areas of increased westerly downslope flow can be expected along and just east of the Cascades in the Columbia River Basin. Sustained winds 10-15 mph (locally higher in the Cascade Gaps) overlap with afternoon relative humidity reductions to around 10-20 percent. An Elevated delineation was added with this outlook to support this potential. ...Dry Thunderstorms... A closed low off the coast of Baja California will bring moisture northward across portions of the Southwest into the Great Basin. On the fringe of this deeper moisture, isolated dry thunderstorm potential will continue across portions of western Colorado into western Wyoming, Utah, far southern Idaho and eastern Nevada. Here precipitable water values drop to around 0.50" or less with more limited coverage. Some mix of wet/dry thunderstorms will be possible in central Utah and west-central Colorado but storm motions around 15-20 kts will likely yield little measurable precipitation. ..Thornton.. 07/17/2025 ...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 1257 AM CDT Thu Jul 17 2025 Valid 171200Z - 181200Z ...Synopsis... A shortwave trough will glance the Pacific Northwest bringing an increase of westerly flow aloft across the Cascades into the Cascade Gaps. As a result, areas of increased westerly downslope flow can be expected along and just east of the Cascades in the Columbia River Basin. Sustained winds 10-15 mph (locally higher in the Cascade Gaps) overlap with afternoon relative humidity reductions to around 10-20 percent. An Elevated delineation was added with this outlook to support this potential. ...Dry Thunderstorms... A closed low off the coast of Baja California will bring moisture northward across portions of the Southwest into the Great Basin. On the fringe of this deeper moisture, isolated dry thunderstorm potential will continue across portions of western Colorado into western Wyoming, Utah, far southern Idaho and eastern Nevada. Here precipitable water values drop to around 0.50" or less with more limited coverage. Some mix of wet/dry thunderstorms will be possible in central Utah and west-central Colorado but storm motions around 15-20 kts will likely yield little measurable precipitation. ..Thornton.. 07/17/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 AM CDT Thu Jul 17 2025 Valid 181200Z - 191200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF NEBRASKA...SOUTH DAKOTA...AND SOUTHERN MINNESOTA INTO IOWA...AND ACROSS PORTIONS OF THE SOUTHERN MID-ATLANTIC... ...SUMMARY... Strong to severe thunderstorms are possible across portions of South Dakota and Nebraska into southern Minnesota and Iowa. Additional strong to severe storms may occur across portions of West Virginia, Virginia and North Carolina. ...NE/SD/MN/IA... Stronger mid/upper level westerly flow will remain confined to the northern tier of the U.S. from the northern Plains to New England. Shortwave impulses will migrate through the westerly flow, but stronger instability will remain displaced to the south of the belt of stronger flow. Nevertheless, a weak surface low and attendant trough is forecast to develop over the northern/central High Plains, and a stalled front will gradually lift north across the northern Plains and portions of the Midwest. Rich boundary layer moisture and a plume of steep midlevel lapse rates will support strong destabilization across parts of KS/NE/SD and the Mid-MO Valley. Vertically veering wind profiles will support rotating storms, while elongated/straight hodographs above 2-3 km appear favorable for hail. Steep low-level lapse rates, and some modest dry air noted between 700-500 mb suggest damaging wind potential is also possible. While some modest low-level hodograph curvature is noted, 0-1 km shear is expected to remain modest, though a tornado or two cannot be ruled out. While this environment generally appears favorable for at least isolated supercells, convective evolution is uncertain given somewhat subtle forcing. Additionally, forecast height tendencies are neutral to possibly small height rises as a shortwave upper ridge builds over the MT/WY after 21z. Capping across portions of the region could limit coverage. Where capping is not an issue, strong instability and modest shear could result in rapid clustering. Furthermore, early convection may be ongoing across parts of ND/SD into MN. How these storms and associated cloudiness evolve through the morning, and any potential outflow generated by this convection also result in uncertainty. Given these uncertainties, despite a favorable airmass, will maintain Marginal (level 1 of 5) probabilities with some expansion of the area. Outlook upgrades may be necessary later if some of the aforementioned uncertainties are resolved. ...Southern Mid-Atlantic vicinity... A weak shortwave impulse is forecast to migrate across the Blue Ridge to the Mid-Atlantic coast in modest westerly flow on the northern periphery of the upper high. A very moist airmass will support moderate destabilization. While shear will remain modest, multicell clusters could produce strong downbursts. If storms can organize along consolidating outflows, increasing potential for damaging winds will occur. ..Leitman.. 07/17/2025 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 AM CDT Thu Jul 17 2025 Valid 181200Z - 191200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF NEBRASKA...SOUTH DAKOTA...AND SOUTHERN MINNESOTA INTO IOWA...AND ACROSS PORTIONS OF THE SOUTHERN MID-ATLANTIC... ...SUMMARY... Strong to severe thunderstorms are possible across portions of South Dakota and Nebraska into southern Minnesota and Iowa. Additional strong to severe storms may occur across portions of West Virginia, Virginia and North Carolina. ...NE/SD/MN/IA... Stronger mid/upper level westerly flow will remain confined to the northern tier of the U.S. from the northern Plains to New England. Shortwave impulses will migrate through the westerly flow, but stronger instability will remain displaced to the south of the belt of stronger flow. Nevertheless, a weak surface low and attendant trough is forecast to develop over the northern/central High Plains, and a stalled front will gradually lift north across the northern Plains and portions of the Midwest. Rich boundary layer moisture and a plume of steep midlevel lapse rates will support strong destabilization across parts of KS/NE/SD and the Mid-MO Valley. Vertically veering wind profiles will support rotating storms, while elongated/straight hodographs above 2-3 km appear favorable for hail. Steep low-level lapse rates, and some modest dry air noted between 700-500 mb suggest damaging wind potential is also possible. While some modest low-level hodograph curvature is noted, 0-1 km shear is expected to remain modest, though a tornado or two cannot be ruled out. While this environment generally appears favorable for at least isolated supercells, convective evolution is uncertain given somewhat subtle forcing. Additionally, forecast height tendencies are neutral to possibly small height rises as a shortwave upper ridge builds over the MT/WY after 21z. Capping across portions of the region could limit coverage. Where capping is not an issue, strong instability and modest shear could result in rapid clustering. Furthermore, early convection may be ongoing across parts of ND/SD into MN. How these storms and associated cloudiness evolve through the morning, and any potential outflow generated by this convection also result in uncertainty. Given these uncertainties, despite a favorable airmass, will maintain Marginal (level 1 of 5) probabilities with some expansion of the area. Outlook upgrades may be necessary later if some of the aforementioned uncertainties are resolved. ...Southern Mid-Atlantic vicinity... A weak shortwave impulse is forecast to migrate across the Blue Ridge to the Mid-Atlantic coast in modest westerly flow on the northern periphery of the upper high. A very moist airmass will support moderate destabilization. While shear will remain modest, multicell clusters could produce strong downbursts. If storms can organize along consolidating outflows, increasing potential for damaging winds will occur. ..Leitman.. 07/17/2025 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 AM CDT Thu Jul 17 2025 Valid 181200Z - 191200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF NEBRASKA...SOUTH DAKOTA...AND SOUTHERN MINNESOTA INTO IOWA...AND ACROSS PORTIONS OF THE SOUTHERN MID-ATLANTIC... ...SUMMARY... Strong to severe thunderstorms are possible across portions of South Dakota and Nebraska into southern Minnesota and Iowa. Additional strong to severe storms may occur across portions of West Virginia, Virginia and North Carolina. ...NE/SD/MN/IA... Stronger mid/upper level westerly flow will remain confined to the northern tier of the U.S. from the northern Plains to New England. Shortwave impulses will migrate through the westerly flow, but stronger instability will remain displaced to the south of the belt of stronger flow. Nevertheless, a weak surface low and attendant trough is forecast to develop over the northern/central High Plains, and a stalled front will gradually lift north across the northern Plains and portions of the Midwest. Rich boundary layer moisture and a plume of steep midlevel lapse rates will support strong destabilization across parts of KS/NE/SD and the Mid-MO Valley. Vertically veering wind profiles will support rotating storms, while elongated/straight hodographs above 2-3 km appear favorable for hail. Steep low-level lapse rates, and some modest dry air noted between 700-500 mb suggest damaging wind potential is also possible. While some modest low-level hodograph curvature is noted, 0-1 km shear is expected to remain modest, though a tornado or two cannot be ruled out. While this environment generally appears favorable for at least isolated supercells, convective evolution is uncertain given somewhat subtle forcing. Additionally, forecast height tendencies are neutral to possibly small height rises as a shortwave upper ridge builds over the MT/WY after 21z. Capping across portions of the region could limit coverage. Where capping is not an issue, strong instability and modest shear could result in rapid clustering. Furthermore, early convection may be ongoing across parts of ND/SD into MN. How these storms and associated cloudiness evolve through the morning, and any potential outflow generated by this convection also result in uncertainty. Given these uncertainties, despite a favorable airmass, will maintain Marginal (level 1 of 5) probabilities with some expansion of the area. Outlook upgrades may be necessary later if some of the aforementioned uncertainties are resolved. ...Southern Mid-Atlantic vicinity... A weak shortwave impulse is forecast to migrate across the Blue Ridge to the Mid-Atlantic coast in modest westerly flow on the northern periphery of the upper high. A very moist airmass will support moderate destabilization. While shear will remain modest, multicell clusters could produce strong downbursts. If storms can organize along consolidating outflows, increasing potential for damaging winds will occur. ..Leitman.. 07/17/2025 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 AM CDT Thu Jul 17 2025 Valid 181200Z - 191200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF NEBRASKA...SOUTH DAKOTA...AND SOUTHERN MINNESOTA INTO IOWA...AND ACROSS PORTIONS OF THE SOUTHERN MID-ATLANTIC... ...SUMMARY... Strong to severe thunderstorms are possible across portions of South Dakota and Nebraska into southern Minnesota and Iowa. Additional strong to severe storms may occur across portions of West Virginia, Virginia and North Carolina. ...NE/SD/MN/IA... Stronger mid/upper level westerly flow will remain confined to the northern tier of the U.S. from the northern Plains to New England. Shortwave impulses will migrate through the westerly flow, but stronger instability will remain displaced to the south of the belt of stronger flow. Nevertheless, a weak surface low and attendant trough is forecast to develop over the northern/central High Plains, and a stalled front will gradually lift north across the northern Plains and portions of the Midwest. Rich boundary layer moisture and a plume of steep midlevel lapse rates will support strong destabilization across parts of KS/NE/SD and the Mid-MO Valley. Vertically veering wind profiles will support rotating storms, while elongated/straight hodographs above 2-3 km appear favorable for hail. Steep low-level lapse rates, and some modest dry air noted between 700-500 mb suggest damaging wind potential is also possible. While some modest low-level hodograph curvature is noted, 0-1 km shear is expected to remain modest, though a tornado or two cannot be ruled out. While this environment generally appears favorable for at least isolated supercells, convective evolution is uncertain given somewhat subtle forcing. Additionally, forecast height tendencies are neutral to possibly small height rises as a shortwave upper ridge builds over the MT/WY after 21z. Capping across portions of the region could limit coverage. Where capping is not an issue, strong instability and modest shear could result in rapid clustering. Furthermore, early convection may be ongoing across parts of ND/SD into MN. How these storms and associated cloudiness evolve through the morning, and any potential outflow generated by this convection also result in uncertainty. Given these uncertainties, despite a favorable airmass, will maintain Marginal (level 1 of 5) probabilities with some expansion of the area. Outlook upgrades may be necessary later if some of the aforementioned uncertainties are resolved. ...Southern Mid-Atlantic vicinity... A weak shortwave impulse is forecast to migrate across the Blue Ridge to the Mid-Atlantic coast in modest westerly flow on the northern periphery of the upper high. A very moist airmass will support moderate destabilization. While shear will remain modest, multicell clusters could produce strong downbursts. If storms can organize along consolidating outflows, increasing potential for damaging winds will occur. ..Leitman.. 07/17/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1250 AM CDT Thu Jul 17 2025 Valid 171200Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN NORTHERN PARTS OF THE GREAT PLAINS AND NEW ENGLAND... ...SUMMARY... A confined corridor of large hail and severe gusts may occur from north-central Montana to southwest North Dakota this evening. Scattered damaging winds and a brief tornado are possible across northern New England this afternoon. Isolated/sporadic damaging winds are also possible across a broad swath of the Northeast/Mid-Atlantic to the southern High Plains. ...Northern Great Plains... A confined corridor of supercell potential is evident across north-central MT to southwest ND this evening. A positive-tilt shortwave trough over the southern Canadian Rockies will progress east along the international border with MT/ND. 00Z HREF guidance is consistent in indicating mid-afternoon storm development over southwest AB. A confined plume of weak buoyancy initially ahead of this activity should temper intensity as it spreads east-southeast into north-central MT by late afternoon. But favorably timed strengthening of a 500-mb westerly jetlet will aid in hodograph elongation. This could support a long-lived/long-track supercell during the evening, impinging on the nose of moderate MLCAPE across southeast MT. Modest mid-level lapse rates and a cooler-than-normal boundary layer should be the primary limiting factor to greater hail/wind magnitudes. But enough signal exists to warrant a narrow level 2-SLGT risk for hail. Low-probability hail/wind threats may persist along the ND/SD border area overnight. ...New England/Northeast... A large MCV over Lower MI will become further absorbed into a shortwave trough that will progress from the Upper Great Lakes to the ON/QC border area by early evening. This will help broaden a swath of enhanced 850-700 mb west-southwesterlies from PA/NJ north. But further weakening of already marginal mid-level lapse rates, owing to the influence of the MCV, should yield a pocket of 500-mb temperatures warming to -4 C in the Hudson Valley vicinity by late afternoon. This will likely limit convective coverage across the Northeast to southern New England vicinity. Scattered, mainly discrete, convection is anticipated along the QC border across northern New England. A few weak supercells are probable, capable of mainly damaging winds and a brief tornado. ...Lower Mid-Atlantic to the southern High Plains... Scattered to widespread thunderstorms are expected west of the Appalachians along a large-scale west/east-oriented convective outflow, augmented by a surface cold front stalling in the southern High Plains. Ample buoyancy south of the outflow/front will support sporadic wet microbursts. Modest deep-layer shear and warm 500-mb temperatures should modulate overall organization/coverage. Isolated damaging winds are also expected east of the central Appalachians, where storm coverage should be reduced but downbursts are possible. ..Grams/Thornton.. 07/17/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1250 AM CDT Thu Jul 17 2025 Valid 171200Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN NORTHERN PARTS OF THE GREAT PLAINS AND NEW ENGLAND... ...SUMMARY... A confined corridor of large hail and severe gusts may occur from north-central Montana to southwest North Dakota this evening. Scattered damaging winds and a brief tornado are possible across northern New England this afternoon. Isolated/sporadic damaging winds are also possible across a broad swath of the Northeast/Mid-Atlantic to the southern High Plains. ...Northern Great Plains... A confined corridor of supercell potential is evident across north-central MT to southwest ND this evening. A positive-tilt shortwave trough over the southern Canadian Rockies will progress east along the international border with MT/ND. 00Z HREF guidance is consistent in indicating mid-afternoon storm development over southwest AB. A confined plume of weak buoyancy initially ahead of this activity should temper intensity as it spreads east-southeast into north-central MT by late afternoon. But favorably timed strengthening of a 500-mb westerly jetlet will aid in hodograph elongation. This could support a long-lived/long-track supercell during the evening, impinging on the nose of moderate MLCAPE across southeast MT. Modest mid-level lapse rates and a cooler-than-normal boundary layer should be the primary limiting factor to greater hail/wind magnitudes. But enough signal exists to warrant a narrow level 2-SLGT risk for hail. Low-probability hail/wind threats may persist along the ND/SD border area overnight. ...New England/Northeast... A large MCV over Lower MI will become further absorbed into a shortwave trough that will progress from the Upper Great Lakes to the ON/QC border area by early evening. This will help broaden a swath of enhanced 850-700 mb west-southwesterlies from PA/NJ north. But further weakening of already marginal mid-level lapse rates, owing to the influence of the MCV, should yield a pocket of 500-mb temperatures warming to -4 C in the Hudson Valley vicinity by late afternoon. This will likely limit convective coverage across the Northeast to southern New England vicinity. Scattered, mainly discrete, convection is anticipated along the QC border across northern New England. A few weak supercells are probable, capable of mainly damaging winds and a brief tornado. ...Lower Mid-Atlantic to the southern High Plains... Scattered to widespread thunderstorms are expected west of the Appalachians along a large-scale west/east-oriented convective outflow, augmented by a surface cold front stalling in the southern High Plains. Ample buoyancy south of the outflow/front will support sporadic wet microbursts. Modest deep-layer shear and warm 500-mb temperatures should modulate overall organization/coverage. Isolated damaging winds are also expected east of the central Appalachians, where storm coverage should be reduced but downbursts are possible. ..Grams/Thornton.. 07/17/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1250 AM CDT Thu Jul 17 2025 Valid 171200Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN NORTHERN PARTS OF THE GREAT PLAINS AND NEW ENGLAND... ...SUMMARY... A confined corridor of large hail and severe gusts may occur from north-central Montana to southwest North Dakota this evening. Scattered damaging winds and a brief tornado are possible across northern New England this afternoon. Isolated/sporadic damaging winds are also possible across a broad swath of the Northeast/Mid-Atlantic to the southern High Plains. ...Northern Great Plains... A confined corridor of supercell potential is evident across north-central MT to southwest ND this evening. A positive-tilt shortwave trough over the southern Canadian Rockies will progress east along the international border with MT/ND. 00Z HREF guidance is consistent in indicating mid-afternoon storm development over southwest AB. A confined plume of weak buoyancy initially ahead of this activity should temper intensity as it spreads east-southeast into north-central MT by late afternoon. But favorably timed strengthening of a 500-mb westerly jetlet will aid in hodograph elongation. This could support a long-lived/long-track supercell during the evening, impinging on the nose of moderate MLCAPE across southeast MT. Modest mid-level lapse rates and a cooler-than-normal boundary layer should be the primary limiting factor to greater hail/wind magnitudes. But enough signal exists to warrant a narrow level 2-SLGT risk for hail. Low-probability hail/wind threats may persist along the ND/SD border area overnight. ...New England/Northeast... A large MCV over Lower MI will become further absorbed into a shortwave trough that will progress from the Upper Great Lakes to the ON/QC border area by early evening. This will help broaden a swath of enhanced 850-700 mb west-southwesterlies from PA/NJ north. But further weakening of already marginal mid-level lapse rates, owing to the influence of the MCV, should yield a pocket of 500-mb temperatures warming to -4 C in the Hudson Valley vicinity by late afternoon. This will likely limit convective coverage across the Northeast to southern New England vicinity. Scattered, mainly discrete, convection is anticipated along the QC border across northern New England. A few weak supercells are probable, capable of mainly damaging winds and a brief tornado. ...Lower Mid-Atlantic to the southern High Plains... Scattered to widespread thunderstorms are expected west of the Appalachians along a large-scale west/east-oriented convective outflow, augmented by a surface cold front stalling in the southern High Plains. Ample buoyancy south of the outflow/front will support sporadic wet microbursts. Modest deep-layer shear and warm 500-mb temperatures should modulate overall organization/coverage. Isolated damaging winds are also expected east of the central Appalachians, where storm coverage should be reduced but downbursts are possible. ..Grams/Thornton.. 07/17/2025 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1250 AM CDT Thu Jul 17 2025 Valid 171200Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN NORTHERN PARTS OF THE GREAT PLAINS AND NEW ENGLAND... ...SUMMARY... A confined corridor of large hail and severe gusts may occur from north-central Montana to southwest North Dakota this evening. Scattered damaging winds and a brief tornado are possible across northern New England this afternoon. Isolated/sporadic damaging winds are also possible across a broad swath of the Northeast/Mid-Atlantic to the southern High Plains. ...Northern Great Plains... A confined corridor of supercell potential is evident across north-central MT to southwest ND this evening. A positive-tilt shortwave trough over the southern Canadian Rockies will progress east along the international border with MT/ND. 00Z HREF guidance is consistent in indicating mid-afternoon storm development over southwest AB. A confined plume of weak buoyancy initially ahead of this activity should temper intensity as it spreads east-southeast into north-central MT by late afternoon. But favorably timed strengthening of a 500-mb westerly jetlet will aid in hodograph elongation. This could support a long-lived/long-track supercell during the evening, impinging on the nose of moderate MLCAPE across southeast MT. Modest mid-level lapse rates and a cooler-than-normal boundary layer should be the primary limiting factor to greater hail/wind magnitudes. But enough signal exists to warrant a narrow level 2-SLGT risk for hail. Low-probability hail/wind threats may persist along the ND/SD border area overnight. ...New England/Northeast... A large MCV over Lower MI will become further absorbed into a shortwave trough that will progress from the Upper Great Lakes to the ON/QC border area by early evening. This will help broaden a swath of enhanced 850-700 mb west-southwesterlies from PA/NJ north. But further weakening of already marginal mid-level lapse rates, owing to the influence of the MCV, should yield a pocket of 500-mb temperatures warming to -4 C in the Hudson Valley vicinity by late afternoon. This will likely limit convective coverage across the Northeast to southern New England vicinity. Scattered, mainly discrete, convection is anticipated along the QC border across northern New England. A few weak supercells are probable, capable of mainly damaging winds and a brief tornado. ...Lower Mid-Atlantic to the southern High Plains... Scattered to widespread thunderstorms are expected west of the Appalachians along a large-scale west/east-oriented convective outflow, augmented by a surface cold front stalling in the southern High Plains. Ample buoyancy south of the outflow/front will support sporadic wet microbursts. Modest deep-layer shear and warm 500-mb temperatures should modulate overall organization/coverage. Isolated damaging winds are also expected east of the central Appalachians, where storm coverage should be reduced but downbursts are possible. ..Grams/Thornton.. 07/17/2025 Read more

WW 0519 Status Updates
STATUS REPORT ON WW 519 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 25 SW DEN TO 25 NE DEN TO 40 E LAA. WW 519 WILL BE ALLOWED TO EXPIRE AT 170400Z. ..THOMPSON..07/17/25 ATTN...WFO...BOU...PUB...GLD...CYS... STATUS REPORT FOR WS 519 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS COC001-005-009-011-025-031-035-039-041-059-061-071-073-089-099- 101-170400- CO . COLORADO COUNTIES INCLUDED ARE ADAMS ARAPAHOE BACA BENT CROWLEY DENVER DOUGLAS ELBERT EL PASO JEFFERSON KIOWA LAS ANIMAS LINCOLN OTERO PROWERS PUEBLO THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

WW 0519 Status Updates
STATUS REPORT ON WW 519 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 25 SW DEN TO 25 NE DEN TO 40 E LAA. WW 519 WILL BE ALLOWED TO EXPIRE AT 170400Z. ..THOMPSON..07/17/25 ATTN...WFO...BOU...PUB...GLD...CYS... STATUS REPORT FOR WS 519 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS COC001-005-009-011-025-031-035-039-041-059-061-071-073-089-099- 101-170400- CO . COLORADO COUNTIES INCLUDED ARE ADAMS ARAPAHOE BACA BENT CROWLEY DENVER DOUGLAS ELBERT EL PASO JEFFERSON KIOWA LAS ANIMAS LINCOLN OTERO PROWERS PUEBLO THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

MD 1697 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR EXTREME SOUTHWEST KANSAS AND THE OKLAHOMA PANHANDLE
Mesoscale Discussion 1697 NWS Storm Prediction Center Norman OK 0853 PM CDT Wed Jul 16 2025 Areas affected...Extreme southwest Kansas and the Oklahoma Panhandle Concerning...Severe potential...Watch unlikely Valid 170153Z - 170330Z Probability of Watch Issuance...5 percent SUMMARY...Storm cluster will continue discrete propagation into the Oklahoma Panhandle before weakening. Isolated severe gusts will be the main threat through 03-04z. DISCUSSION...A cluster of storms has displayed a tendency for discrete propagation/new development to the southwest, on the immediate cool side of a slow moving front. Per the recent measured gusts as high as 78 mph at DDC, the mesoscale environment remains supportive of severe outflow gusts given lingering steep low-level lapse rates and a narrow zone where MLCAPE is still near 3000 J/kg. The storm cluster will likely spread into the central OK Panhandle from now until 03-04z, with weakening expected thereafter as the low levels stabilize gradually. In the interim, occasional severe outflow gusts will remain possible, but the area affected and the duration of the threat are too confined for a watch. ..Thompson/Hart.. 07/17/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...DDC...AMA... LAT...LON 37410022 37040054 36730093 36530127 36530163 36740173 37300138 37690091 37770055 37670040 37410022 MOST PROBABLE PEAK WIND GUST...65-80 MPH MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN Read more

WW 519 SEVERE TSTM CO NE WY 162040Z - 170400Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 519 NWS Storm Prediction Center Norman OK 240 PM MDT Wed Jul 16 2025 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Eastern Colorado Nebraska Panhandle Southeast Wyoming * Effective this Wednesday afternoon and evening from 240 PM until 1000 PM MDT. * Primary threats include... Scattered large hail and isolated very large hail events to 2 inches in diameter possible Scattered damaging wind gusts to 70 mph possible A tornado or two possible SUMMARY...Scattered thunderstorms developing near Interstate 25 will continue to intensify this afternoon and move eastward across the Watch. Appreciably strong deep-layer shear will support a mix of supercells and severe multicells across mainly the northern half of the Watch. Large hail and severe gusts will be the primary hazards with the stronger storms, but a tornado is possible. Severe thunderstorms posing primarily a severe-wind risk are possible later this evening as storms congeal into a likely cluster across southeast Colorado. The severe thunderstorm watch area is approximately along and 65 statute miles east and west of a line from 40 miles north of Cheyenne WY to 25 miles west southwest of Springfield CO. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU9). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. && OTHER WATCH INFORMATION...CONTINUE...WW 517...WW 518... AVIATION...A few severe thunderstorms with hail surface and aloft to 2 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 27025. ...Smith Read more

MD 1695 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR MICHIGAN...NORTHEASTERN INDIANA...NORTHWESTERN OHIO
Mesoscale Discussion 1695 NWS Storm Prediction Center Norman OK 0643 PM CDT Wed Jul 16 2025 Areas affected...Michigan...northeastern Indiana...northwestern Ohio Concerning...Severe potential...Watch unlikely Valid 162343Z - 170115Z Probability of Watch Issuance...20 percent SUMMARY...A few instances of strong to severe wind may linger downstream of WW520. Overall, the threat is likely to diminish and downstream watch issuance is unlikely. DISCUSSION...A line of storms moving across northern Indiana has shown signs of weakening over the last hour. A couple of reports around 40-55 mph were noted earlier. The downstream air mass remains unstable but deep layer shear is overall marginal. CAM guidance generally suggests this line will continue to weaken with loss of daytime heating. A downstream watch is unlikely to be needed. ..Thornton.. 07/16/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...CLE...ILN...DTX...IWX...GRR...IND... LAT...LON 41668612 42088564 42238461 42098405 41728360 41428349 40978379 40738393 40568402 40308470 40298527 40598590 40688609 41668612 MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH Read more

WW 0519 Status Updates
STATUS REPORT ON WW 519 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 30 WNW DEN TO 15 SE CYS TO 40 ESE CYS TO 30 SSE ITR. ..THOMPSON..07/17/25 ATTN...WFO...BOU...PUB...GLD...CYS... STATUS REPORT FOR WS 519 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS COC001-005-009-011-013-014-017-025-031-035-039-041-059-061-063- 071-073-087-089-099-101-121-123-170240- CO . COLORADO COUNTIES INCLUDED ARE ADAMS ARAPAHOE BACA BENT BOULDER BROOMFIELD CHEYENNE CROWLEY DENVER DOUGLAS ELBERT EL PASO JEFFERSON KIOWA KIT CARSON LAS ANIMAS LINCOLN MORGAN OTERO PROWERS PUEBLO WASHINGTON WELD THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0750 PM CDT Wed Jul 16 2025 Valid 170100Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM EASTERN CO TO THE LOWER MO VALLEY...LOWER MI TO THE LOWER OH VALLEY...AND THE MID-ATLANTIC... ...SUMMARY... Isolated severe thunderstorms remain possible tonight across eastern Colorado to the Lower Missouri Valley. Isolated damaging winds remain possible this evening across parts of the Midwest and the Mid-Atlantic States. ...Eastern CO to the Lower MO Valley... A trio of rather widely-spaced and recently weakening supercells are ongoing across eastern CO to southwest KS. With pronounced MLCIN downstream, that will further increase nocturnally, these surface-based storms should diminish. Widespread elevated convection is expected across northern KS into the Lower MO Valley overnight, north of the southward-sagging cold front. Marginal severe hail will be possible with initial updrafts before clustering in a largely west/east-orientation. Modest effective bulk shear will limit the overall threat. ...Lower MI/Lower OH Valley to the Mid-Atlantic States... A generally weakening broken line of convection is ongoing from western Lower MI to southern IL. The MI portion has shown some recent uptick, closer to the MCV over central Lake MI. Adequate deep-layer shear and the recent convective increase may foster a sporadic damaging wind threat. But the downstream airmass of weak lapse rates and MLCAPE, as sampled by the 00Z DTX/APX soundings, will marginalize severe potential tonight. Farther east, slow-moving thunderstorms will drift east and/or weaken across parts of the Mid-Atlantic States tonight. But pockets of moderate buoyancy and modest deep-layer shear could support localized damaging winds for a few more hours. ..Grams.. 07/17/2025 Read more