SPC Jul 17, 2025 0730 UTC Day 3 Severe Thunderstorm Outlook

6 days 15 hours ago
SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0155 AM CDT Thu Jul 17 2025 Valid 191200Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE NORTHERN/CENTRAL PLAINS TO THE OHIO VALLEY... ...SUMMARY... Strong to severe storms are possible from the northern and central High Plains to the Mid-Mississippi and Lower Ohio Valleys on Saturday. ...Mid-MS/Lower OH Valley vicinity... Modestly enhanced westerly mid/upper flow will continue on Saturday from the northern Plains to the Great Lakes vicinity. Convection may be ongoing during the morning, perhaps across the Mid-MS Valley or Lake Michigan vicinity in the form of a remnant MCS from the Day 2/Friday period. Meanwhile, a cold front will sag southward across the Upper Midwest toward the Mid-MS valley through early Sunday. Ahead of any ongoing convection and the front, a very moist airmass will be in place and a corridor of strong destabilization is forecast. While upper forcing will remain somewhat nebulous, an MCV or outflow from morning storms could be a focus for severe thunderstorm develop during the afternoon from the IA/IL/MO tri-state area eastward along the moisture/instability gradient into the Ohio Valley. Damaging gusts would be the main hazard with this activity. ...Northern/Central Plains... South/southeasterly low-level flow will transport rich boundary-layer moisture northwest into western NE/SD/ND and perhaps eastern MT along a surface trough. A shortwave ridge over the northern Plains will shift east and weaken by evening, and 30-40 kt mid/upper westerly flow will overspread a narrow corridor of moderate to strong instability. While upper forcing will be nebulous, convergence along the surface trough in the moist low-level upslope flow regime may be sufficient for isolated strong to severe storm development. Vertically veering wind profiles and somewhat elongated hodographs above 3 km suggest supercells will be possible, posing a risk for hail. Steep low-level lapse rates also could support strong outflow winds. ..Leitman.. 07/17/2025 Read more

SPC Jul 17, 2025 0730 UTC Day 3 Severe Thunderstorm Outlook

6 days 15 hours ago
SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0155 AM CDT Thu Jul 17 2025 Valid 191200Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE NORTHERN/CENTRAL PLAINS TO THE OHIO VALLEY... ...SUMMARY... Strong to severe storms are possible from the northern and central High Plains to the Mid-Mississippi and Lower Ohio Valleys on Saturday. ...Mid-MS/Lower OH Valley vicinity... Modestly enhanced westerly mid/upper flow will continue on Saturday from the northern Plains to the Great Lakes vicinity. Convection may be ongoing during the morning, perhaps across the Mid-MS Valley or Lake Michigan vicinity in the form of a remnant MCS from the Day 2/Friday period. Meanwhile, a cold front will sag southward across the Upper Midwest toward the Mid-MS valley through early Sunday. Ahead of any ongoing convection and the front, a very moist airmass will be in place and a corridor of strong destabilization is forecast. While upper forcing will remain somewhat nebulous, an MCV or outflow from morning storms could be a focus for severe thunderstorm develop during the afternoon from the IA/IL/MO tri-state area eastward along the moisture/instability gradient into the Ohio Valley. Damaging gusts would be the main hazard with this activity. ...Northern/Central Plains... South/southeasterly low-level flow will transport rich boundary-layer moisture northwest into western NE/SD/ND and perhaps eastern MT along a surface trough. A shortwave ridge over the northern Plains will shift east and weaken by evening, and 30-40 kt mid/upper westerly flow will overspread a narrow corridor of moderate to strong instability. While upper forcing will be nebulous, convergence along the surface trough in the moist low-level upslope flow regime may be sufficient for isolated strong to severe storm development. Vertically veering wind profiles and somewhat elongated hodographs above 3 km suggest supercells will be possible, posing a risk for hail. Steep low-level lapse rates also could support strong outflow winds. ..Leitman.. 07/17/2025 Read more

SPC Jul 17, 2025 0730 UTC Day 3 Severe Thunderstorm Outlook

6 days 15 hours ago
SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0155 AM CDT Thu Jul 17 2025 Valid 191200Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE NORTHERN/CENTRAL PLAINS TO THE OHIO VALLEY... ...SUMMARY... Strong to severe storms are possible from the northern and central High Plains to the Mid-Mississippi and Lower Ohio Valleys on Saturday. ...Mid-MS/Lower OH Valley vicinity... Modestly enhanced westerly mid/upper flow will continue on Saturday from the northern Plains to the Great Lakes vicinity. Convection may be ongoing during the morning, perhaps across the Mid-MS Valley or Lake Michigan vicinity in the form of a remnant MCS from the Day 2/Friday period. Meanwhile, a cold front will sag southward across the Upper Midwest toward the Mid-MS valley through early Sunday. Ahead of any ongoing convection and the front, a very moist airmass will be in place and a corridor of strong destabilization is forecast. While upper forcing will remain somewhat nebulous, an MCV or outflow from morning storms could be a focus for severe thunderstorm develop during the afternoon from the IA/IL/MO tri-state area eastward along the moisture/instability gradient into the Ohio Valley. Damaging gusts would be the main hazard with this activity. ...Northern/Central Plains... South/southeasterly low-level flow will transport rich boundary-layer moisture northwest into western NE/SD/ND and perhaps eastern MT along a surface trough. A shortwave ridge over the northern Plains will shift east and weaken by evening, and 30-40 kt mid/upper westerly flow will overspread a narrow corridor of moderate to strong instability. While upper forcing will be nebulous, convergence along the surface trough in the moist low-level upslope flow regime may be sufficient for isolated strong to severe storm development. Vertically veering wind profiles and somewhat elongated hodographs above 3 km suggest supercells will be possible, posing a risk for hail. Steep low-level lapse rates also could support strong outflow winds. ..Leitman.. 07/17/2025 Read more

SPC Day 2 Fire Weather Outlook

6 days 16 hours ago
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1258 AM CDT Thu Jul 17 2025 Valid 181200Z - 191200Z ...Synopsis... A deeper trough will traverse the Pacific Northwest on D2/Friday bringing more widespread Elevated conditions across the areas along and east of the Cascades. Afternoon relative humidity around 10-20 percent will overlap sustained westerly winds at 10-15 mph (locally higher). Some locally Critical conditions may persist for a couple of hours where terrain enhancements favor locally stronger winds in the Cascade Gaps. ...Dry Thunderstorms... The western shortwave will bring forcing for ascent across portions of northern Nevada into southern Idaho and eastern Wyoming. This area remains on the periphery of deeper moisture across the Southwest into the Great Basin. High based convection and very dry boundary layer conditions will favor little to no measurable precipitation with potential for new ignitions from lightning. ..Thornton.. 07/17/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook

6 days 16 hours ago
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1258 AM CDT Thu Jul 17 2025 Valid 181200Z - 191200Z ...Synopsis... A deeper trough will traverse the Pacific Northwest on D2/Friday bringing more widespread Elevated conditions across the areas along and east of the Cascades. Afternoon relative humidity around 10-20 percent will overlap sustained westerly winds at 10-15 mph (locally higher). Some locally Critical conditions may persist for a couple of hours where terrain enhancements favor locally stronger winds in the Cascade Gaps. ...Dry Thunderstorms... The western shortwave will bring forcing for ascent across portions of northern Nevada into southern Idaho and eastern Wyoming. This area remains on the periphery of deeper moisture across the Southwest into the Great Basin. High based convection and very dry boundary layer conditions will favor little to no measurable precipitation with potential for new ignitions from lightning. ..Thornton.. 07/17/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook

6 days 16 hours ago
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1258 AM CDT Thu Jul 17 2025 Valid 181200Z - 191200Z ...Synopsis... A deeper trough will traverse the Pacific Northwest on D2/Friday bringing more widespread Elevated conditions across the areas along and east of the Cascades. Afternoon relative humidity around 10-20 percent will overlap sustained westerly winds at 10-15 mph (locally higher). Some locally Critical conditions may persist for a couple of hours where terrain enhancements favor locally stronger winds in the Cascade Gaps. ...Dry Thunderstorms... The western shortwave will bring forcing for ascent across portions of northern Nevada into southern Idaho and eastern Wyoming. This area remains on the periphery of deeper moisture across the Southwest into the Great Basin. High based convection and very dry boundary layer conditions will favor little to no measurable precipitation with potential for new ignitions from lightning. ..Thornton.. 07/17/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook

6 days 16 hours ago
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1258 AM CDT Thu Jul 17 2025 Valid 181200Z - 191200Z ...Synopsis... A deeper trough will traverse the Pacific Northwest on D2/Friday bringing more widespread Elevated conditions across the areas along and east of the Cascades. Afternoon relative humidity around 10-20 percent will overlap sustained westerly winds at 10-15 mph (locally higher). Some locally Critical conditions may persist for a couple of hours where terrain enhancements favor locally stronger winds in the Cascade Gaps. ...Dry Thunderstorms... The western shortwave will bring forcing for ascent across portions of northern Nevada into southern Idaho and eastern Wyoming. This area remains on the periphery of deeper moisture across the Southwest into the Great Basin. High based convection and very dry boundary layer conditions will favor little to no measurable precipitation with potential for new ignitions from lightning. ..Thornton.. 07/17/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook

6 days 16 hours ago
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

6 days 16 hours ago
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

6 days 16 hours ago
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

6 days 16 hours ago
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

6 days 16 hours ago
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 Jul 17, 2025 0600 UTC Day 2 Convective Outlook

6 days 16 hours ago
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 Jul 17, 2025 0600 UTC Day 2 Convective Outlook

6 days 16 hours ago
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 Jul 17, 2025 0600 UTC Day 2 Convective Outlook

6 days 16 hours ago
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 Jul 17, 2025 0600 UTC Day 2 Convective Outlook

6 days 16 hours ago
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 Jul 17, 2025 0600 UTC Day 1 Convective Outlook

6 days 16 hours ago
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 Jul 17, 2025 0600 UTC Day 1 Convective Outlook

6 days 16 hours ago
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 Jul 17, 2025 0600 UTC Day 1 Convective Outlook

6 days 16 hours ago
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 Jul 17, 2025 0600 UTC Day 1 Convective Outlook

6 days 16 hours ago
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