Aggregator

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1150 AM CDT Wed Sep 10 2025 Valid 101700Z - 111200Z ...Washington... Isolated thunderstorms are expected along the higher terrain of the Cascade Range in central and north-central WA this afternoon. PWAT values in the 0.65-0.85 inch range will support wetting rain cores in slower moving thunderstorms. However, lightning strikes outside of heavier precipitation cores could lead to some new ignitions in drought stressed, heavier fuels. Gusty outflow winds could also impact existing active fires in the Washington Cascades this afternoon. ...Eastern Nevada/western Utah... An advancing mid-level jet, relatively dry boundary layer and daytime mixing will support strong, sustained south to southwest winds of up to 25 mph across eastern NV and western UT this afternoon. Daytime relative humidity as low as 10% combined with the south to southwest winds will support an elevated fire weather threat across this region, despite marginal fuel dryness. A slight northward expansion of Elevated highlights into far northwestern UT and far south central ID was prudent based on latest model guidance and current relative humidity in northwestern UT already below 15%. ..Williams.. 09/10/2025 .PREV DISCUSSION... /ISSUED 1245 AM CDT Wed Sep 10 2025/ ...Synopsis... The upper-level trough in the West will continue its slow eastward progress into the Great Basin. The mid-level jet will intensify within the southern and eastern Great Basin. Cooler air aloft and marginal mid-level ascent will also promote some convection in Washington. ...Washington... A pocket of drier fuels exists in the Columbia Basin and nearby vicinity. Recent lightning activity has led to fire starts. Given the current convection in Oregon moving north and west around the upper-low, some lightning activity can be expected early this morning. Additional thunderstorms appear possible during the afternoon and perhaps again overnight tonight. However, those storms may pose a lesser lightning ignition threat given increasing PWAT values through the period. ...Eastern Nevada/western Utah... Strong surface winds of 15-25 mph will overspread parts of the Great Basin beneath the mid-level jet. RH could fall near 10% locally, but 15-20% will be more common. Given the potential for critical meteorological conditions, elevated fire weather concerns are expected despite the unfavorable to marginal fuel receptiveness in these areas. ...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 1150 AM CDT Wed Sep 10 2025 Valid 101700Z - 111200Z ...Washington... Isolated thunderstorms are expected along the higher terrain of the Cascade Range in central and north-central WA this afternoon. PWAT values in the 0.65-0.85 inch range will support wetting rain cores in slower moving thunderstorms. However, lightning strikes outside of heavier precipitation cores could lead to some new ignitions in drought stressed, heavier fuels. Gusty outflow winds could also impact existing active fires in the Washington Cascades this afternoon. ...Eastern Nevada/western Utah... An advancing mid-level jet, relatively dry boundary layer and daytime mixing will support strong, sustained south to southwest winds of up to 25 mph across eastern NV and western UT this afternoon. Daytime relative humidity as low as 10% combined with the south to southwest winds will support an elevated fire weather threat across this region, despite marginal fuel dryness. A slight northward expansion of Elevated highlights into far northwestern UT and far south central ID was prudent based on latest model guidance and current relative humidity in northwestern UT already below 15%. ..Williams.. 09/10/2025 .PREV DISCUSSION... /ISSUED 1245 AM CDT Wed Sep 10 2025/ ...Synopsis... The upper-level trough in the West will continue its slow eastward progress into the Great Basin. The mid-level jet will intensify within the southern and eastern Great Basin. Cooler air aloft and marginal mid-level ascent will also promote some convection in Washington. ...Washington... A pocket of drier fuels exists in the Columbia Basin and nearby vicinity. Recent lightning activity has led to fire starts. Given the current convection in Oregon moving north and west around the upper-low, some lightning activity can be expected early this morning. Additional thunderstorms appear possible during the afternoon and perhaps again overnight tonight. However, those storms may pose a lesser lightning ignition threat given increasing PWAT values through the period. ...Eastern Nevada/western Utah... Strong surface winds of 15-25 mph will overspread parts of the Great Basin beneath the mid-level jet. RH could fall near 10% locally, but 15-20% will be more common. Given the potential for critical meteorological conditions, elevated fire weather concerns are expected despite the unfavorable to marginal fuel receptiveness in these areas. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Wed Sep 10 2025 Valid 101630Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTH-CENTRAL HIGH PLAINS/FRONT RANGE AND GREAT BASIN/INTERIOR WEST... ...SUMMARY... A few severe storms could occur this afternoon and early evening across the north-central High Plains and Great Basin. ...High Plains/Front Range... As the upper ridge tends to abate/shift away, the region will begin to be influenced by the upper trough over the West. While some stronger storms could occur across a relatively broad north-south extent of the High Plains, portions of eastern Wyoming and the northern Colorado Front Range and immediately adjacent High Plains are expected to be influenced by somewhat stronger mid-level westerlies (25 kt), aside from steep lapse rates and moderate buoyancy. Low severe probabilities have been introduced for what should be an isolated/relatively marginal severe potential later this afternoon into evening. ...Great Basin/Interior West... The region will be influenced by a belt of stronger cyclonic flow aloft preceding the upper low centered over northern California. Adequate moisture, steep lapse rates, and stronger deep-layer winds could allow for some storms to produce gusty winds and small hail, mainly across central/northern Nevada into southwest Idaho. ..Guyer/Weinman.. 09/10/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Wed Sep 10 2025 Valid 101630Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTH-CENTRAL HIGH PLAINS/FRONT RANGE AND GREAT BASIN/INTERIOR WEST... ...SUMMARY... A few severe storms could occur this afternoon and early evening across the north-central High Plains and Great Basin. ...High Plains/Front Range... As the upper ridge tends to abate/shift away, the region will begin to be influenced by the upper trough over the West. While some stronger storms could occur across a relatively broad north-south extent of the High Plains, portions of eastern Wyoming and the northern Colorado Front Range and immediately adjacent High Plains are expected to be influenced by somewhat stronger mid-level westerlies (25 kt), aside from steep lapse rates and moderate buoyancy. Low severe probabilities have been introduced for what should be an isolated/relatively marginal severe potential later this afternoon into evening. ...Great Basin/Interior West... The region will be influenced by a belt of stronger cyclonic flow aloft preceding the upper low centered over northern California. Adequate moisture, steep lapse rates, and stronger deep-layer winds could allow for some storms to produce gusty winds and small hail, mainly across central/northern Nevada into southwest Idaho. ..Guyer/Weinman.. 09/10/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Wed Sep 10 2025 Valid 101630Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTH-CENTRAL HIGH PLAINS/FRONT RANGE AND GREAT BASIN/INTERIOR WEST... ...SUMMARY... A few severe storms could occur this afternoon and early evening across the north-central High Plains and Great Basin. ...High Plains/Front Range... As the upper ridge tends to abate/shift away, the region will begin to be influenced by the upper trough over the West. While some stronger storms could occur across a relatively broad north-south extent of the High Plains, portions of eastern Wyoming and the northern Colorado Front Range and immediately adjacent High Plains are expected to be influenced by somewhat stronger mid-level westerlies (25 kt), aside from steep lapse rates and moderate buoyancy. Low severe probabilities have been introduced for what should be an isolated/relatively marginal severe potential later this afternoon into evening. ...Great Basin/Interior West... The region will be influenced by a belt of stronger cyclonic flow aloft preceding the upper low centered over northern California. Adequate moisture, steep lapse rates, and stronger deep-layer winds could allow for some storms to produce gusty winds and small hail, mainly across central/northern Nevada into southwest Idaho. ..Guyer/Weinman.. 09/10/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Wed Sep 10 2025 Valid 101630Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTH-CENTRAL HIGH PLAINS/FRONT RANGE AND GREAT BASIN/INTERIOR WEST... ...SUMMARY... A few severe storms could occur this afternoon and early evening across the north-central High Plains and Great Basin. ...High Plains/Front Range... As the upper ridge tends to abate/shift away, the region will begin to be influenced by the upper trough over the West. While some stronger storms could occur across a relatively broad north-south extent of the High Plains, portions of eastern Wyoming and the northern Colorado Front Range and immediately adjacent High Plains are expected to be influenced by somewhat stronger mid-level westerlies (25 kt), aside from steep lapse rates and moderate buoyancy. Low severe probabilities have been introduced for what should be an isolated/relatively marginal severe potential later this afternoon into evening. ...Great Basin/Interior West... The region will be influenced by a belt of stronger cyclonic flow aloft preceding the upper low centered over northern California. Adequate moisture, steep lapse rates, and stronger deep-layer winds could allow for some storms to produce gusty winds and small hail, mainly across central/northern Nevada into southwest Idaho. ..Guyer/Weinman.. 09/10/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Wed Sep 10 2025 Valid 101630Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTH-CENTRAL HIGH PLAINS/FRONT RANGE AND GREAT BASIN/INTERIOR WEST... ...SUMMARY... A few severe storms could occur this afternoon and early evening across the north-central High Plains and Great Basin. ...High Plains/Front Range... As the upper ridge tends to abate/shift away, the region will begin to be influenced by the upper trough over the West. While some stronger storms could occur across a relatively broad north-south extent of the High Plains, portions of eastern Wyoming and the northern Colorado Front Range and immediately adjacent High Plains are expected to be influenced by somewhat stronger mid-level westerlies (25 kt), aside from steep lapse rates and moderate buoyancy. Low severe probabilities have been introduced for what should be an isolated/relatively marginal severe potential later this afternoon into evening. ...Great Basin/Interior West... The region will be influenced by a belt of stronger cyclonic flow aloft preceding the upper low centered over northern California. Adequate moisture, steep lapse rates, and stronger deep-layer winds could allow for some storms to produce gusty winds and small hail, mainly across central/northern Nevada into southwest Idaho. ..Guyer/Weinman.. 09/10/2025 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Wed Sep 10 2025 Valid 101630Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTH-CENTRAL HIGH PLAINS/FRONT RANGE AND GREAT BASIN/INTERIOR WEST... ...SUMMARY... A few severe storms could occur this afternoon and early evening across the north-central High Plains and Great Basin. ...High Plains/Front Range... As the upper ridge tends to abate/shift away, the region will begin to be influenced by the upper trough over the West. While some stronger storms could occur across a relatively broad north-south extent of the High Plains, portions of eastern Wyoming and the northern Colorado Front Range and immediately adjacent High Plains are expected to be influenced by somewhat stronger mid-level westerlies (25 kt), aside from steep lapse rates and moderate buoyancy. Low severe probabilities have been introduced for what should be an isolated/relatively marginal severe potential later this afternoon into evening. ...Great Basin/Interior West... The region will be influenced by a belt of stronger cyclonic flow aloft preceding the upper low centered over northern California. Adequate moisture, steep lapse rates, and stronger deep-layer winds could allow for some storms to produce gusty winds and small hail, mainly across central/northern Nevada into southwest Idaho. ..Guyer/Weinman.. 09/10/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0745 AM CDT Wed Sep 10 2025 Valid 101300Z - 111200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Scattered showers and thunderstorms are possible over parts of the Northwest and northern Rockies with more isolated storms over the High Plains. Severe potential is generally low. ...Synopsis... Water-vapor imagery this morning shows an upper low situated over northern CA, and it will remain nearly stationary during the period with a large area of cyclonic flow extending from southern CA into the eastern Great Basin and central Rockies. A downstream upper ridge over the High Plains will feature a lee trough that will act to focus isolated to scattered thunderstorms from MT southward into the central High Plains. Strong heating and weak upslope flow beneath the aforementioned upper-level ridge will favor a few isolated cells developing during peak heating. A couple of the more vigorous storms may be capable of localized strong gusts near 1) NM/OK/TX/CO border, 2) east of the CO Front Range in the High Plains, and 3) in eastern WY. Warming aloft is expected to mitigate the overall potential with these storms. Farther west, a mid-level shortwave trough will move through the base of the West Coast mid- to upper low/trough and to near the UT/NV border by late afternoon/early evening. A corresponding belt of 50-kt southwesterly 500-mb flow will overspread western UT. Isolated dry microbursts may accompany the stronger storms over central UT into western CO during the 22-02z period. Elsewhere, scattered afternoon storms will occur beneath the upper trough from northern NV into OR and western ID, and a few of these storms could produce at least small hail given such cool temperatures aloft and modest deep-layer shear. ..Smith/Broyles.. 09/10/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0745 AM CDT Wed Sep 10 2025 Valid 101300Z - 111200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Scattered showers and thunderstorms are possible over parts of the Northwest and northern Rockies with more isolated storms over the High Plains. Severe potential is generally low. ...Synopsis... Water-vapor imagery this morning shows an upper low situated over northern CA, and it will remain nearly stationary during the period with a large area of cyclonic flow extending from southern CA into the eastern Great Basin and central Rockies. A downstream upper ridge over the High Plains will feature a lee trough that will act to focus isolated to scattered thunderstorms from MT southward into the central High Plains. Strong heating and weak upslope flow beneath the aforementioned upper-level ridge will favor a few isolated cells developing during peak heating. A couple of the more vigorous storms may be capable of localized strong gusts near 1) NM/OK/TX/CO border, 2) east of the CO Front Range in the High Plains, and 3) in eastern WY. Warming aloft is expected to mitigate the overall potential with these storms. Farther west, a mid-level shortwave trough will move through the base of the West Coast mid- to upper low/trough and to near the UT/NV border by late afternoon/early evening. A corresponding belt of 50-kt southwesterly 500-mb flow will overspread western UT. Isolated dry microbursts may accompany the stronger storms over central UT into western CO during the 22-02z period. Elsewhere, scattered afternoon storms will occur beneath the upper trough from northern NV into OR and western ID, and a few of these storms could produce at least small hail given such cool temperatures aloft and modest deep-layer shear. ..Smith/Broyles.. 09/10/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0745 AM CDT Wed Sep 10 2025 Valid 101300Z - 111200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Scattered showers and thunderstorms are possible over parts of the Northwest and northern Rockies with more isolated storms over the High Plains. Severe potential is generally low. ...Synopsis... Water-vapor imagery this morning shows an upper low situated over northern CA, and it will remain nearly stationary during the period with a large area of cyclonic flow extending from southern CA into the eastern Great Basin and central Rockies. A downstream upper ridge over the High Plains will feature a lee trough that will act to focus isolated to scattered thunderstorms from MT southward into the central High Plains. Strong heating and weak upslope flow beneath the aforementioned upper-level ridge will favor a few isolated cells developing during peak heating. A couple of the more vigorous storms may be capable of localized strong gusts near 1) NM/OK/TX/CO border, 2) east of the CO Front Range in the High Plains, and 3) in eastern WY. Warming aloft is expected to mitigate the overall potential with these storms. Farther west, a mid-level shortwave trough will move through the base of the West Coast mid- to upper low/trough and to near the UT/NV border by late afternoon/early evening. A corresponding belt of 50-kt southwesterly 500-mb flow will overspread western UT. Isolated dry microbursts may accompany the stronger storms over central UT into western CO during the 22-02z period. Elsewhere, scattered afternoon storms will occur beneath the upper trough from northern NV into OR and western ID, and a few of these storms could produce at least small hail given such cool temperatures aloft and modest deep-layer shear. ..Smith/Broyles.. 09/10/2025 Read more

000
ABPZ20 KNHC 101130
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
500 AM PDT Wed Sep 10 2025

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

Active Systems:
The National Hurricane Center is issuing advisories on Tropical
Storm Kiko, located in the central Pacific basin just
north-northeast of Oahu in the Hawaiian Islands.

South of Southern and Southwestern Mexico (EP95):
A tropical wave located a couple hundred miles offshore of the coast
of southern Mexico is producing a large area of disorganized showers
and thunderstorms. Environmental conditions are favorable for
development of this system, and a tropical depression is likely to
form by late this week as it moves west-northwestward, roughly
parallel to but offshore of the Mexican coast.
* Formation chance through 48 hours...medium...50 percent.
* Formation chance through 7 days...high...90 percent.

$$
Forecaster Bucci

No tropical cyclones as of Tue, 09 Sep 2025 03:23:14 GMT

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0356 AM CDT Wed Sep 10 2025 Valid 131200Z - 181200Z ...DISCUSSION... Severe potential in the extended forecast period will be tied to a shortwave trough and stronger southwesterly flow aloft emanating from the Rockies over the central US. Flow aloft will increase D4/Saturday as the upper trough begins to overspread the central US. Ascent from the trough will maintain a weak surface low and stationary front over the northern Plains and Upper Midwest. At the same time, a weak cold front will move eastward over the High Plains serving as a focus for thunderstorm development from the Dakotas and MN to the southern Plains each afternoon. Some isolated severe potential is apparent near the surface low/stalled front over the northern Plains and along the cold front farther south through the remainder of the weekend. However, model guidance varies widely on available moisture/buoyancy and the overlap with more robust vertical shear. This continues to cast significant uncertainty on severe probabilities through the first half of the extended forecast period. By early next week, mid-level ridging is expected to strengthen, forcing stronger flow aloft northward as the primary western trough begins to weaken. A second trough will stall over the West as the ridge continues to build. This should favor drier surface conditions while also limiting the overlap of buoyancy with stronger flow aloft. Severe potential appears limited beyond this weekend and into the first half of next week. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0356 AM CDT Wed Sep 10 2025 Valid 131200Z - 181200Z ...DISCUSSION... Severe potential in the extended forecast period will be tied to a shortwave trough and stronger southwesterly flow aloft emanating from the Rockies over the central US. Flow aloft will increase D4/Saturday as the upper trough begins to overspread the central US. Ascent from the trough will maintain a weak surface low and stationary front over the northern Plains and Upper Midwest. At the same time, a weak cold front will move eastward over the High Plains serving as a focus for thunderstorm development from the Dakotas and MN to the southern Plains each afternoon. Some isolated severe potential is apparent near the surface low/stalled front over the northern Plains and along the cold front farther south through the remainder of the weekend. However, model guidance varies widely on available moisture/buoyancy and the overlap with more robust vertical shear. This continues to cast significant uncertainty on severe probabilities through the first half of the extended forecast period. By early next week, mid-level ridging is expected to strengthen, forcing stronger flow aloft northward as the primary western trough begins to weaken. A second trough will stall over the West as the ridge continues to build. This should favor drier surface conditions while also limiting the overlap of buoyancy with stronger flow aloft. Severe potential appears limited beyond this weekend and into the first half of next week. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0356 AM CDT Wed Sep 10 2025 Valid 131200Z - 181200Z ...DISCUSSION... Severe potential in the extended forecast period will be tied to a shortwave trough and stronger southwesterly flow aloft emanating from the Rockies over the central US. Flow aloft will increase D4/Saturday as the upper trough begins to overspread the central US. Ascent from the trough will maintain a weak surface low and stationary front over the northern Plains and Upper Midwest. At the same time, a weak cold front will move eastward over the High Plains serving as a focus for thunderstorm development from the Dakotas and MN to the southern Plains each afternoon. Some isolated severe potential is apparent near the surface low/stalled front over the northern Plains and along the cold front farther south through the remainder of the weekend. However, model guidance varies widely on available moisture/buoyancy and the overlap with more robust vertical shear. This continues to cast significant uncertainty on severe probabilities through the first half of the extended forecast period. By early next week, mid-level ridging is expected to strengthen, forcing stronger flow aloft northward as the primary western trough begins to weaken. A second trough will stall over the West as the ridge continues to build. This should favor drier surface conditions while also limiting the overlap of buoyancy with stronger flow aloft. Severe potential appears limited beyond this weekend and into the first half of next week. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0356 AM CDT Wed Sep 10 2025 Valid 131200Z - 181200Z ...DISCUSSION... Severe potential in the extended forecast period will be tied to a shortwave trough and stronger southwesterly flow aloft emanating from the Rockies over the central US. Flow aloft will increase D4/Saturday as the upper trough begins to overspread the central US. Ascent from the trough will maintain a weak surface low and stationary front over the northern Plains and Upper Midwest. At the same time, a weak cold front will move eastward over the High Plains serving as a focus for thunderstorm development from the Dakotas and MN to the southern Plains each afternoon. Some isolated severe potential is apparent near the surface low/stalled front over the northern Plains and along the cold front farther south through the remainder of the weekend. However, model guidance varies widely on available moisture/buoyancy and the overlap with more robust vertical shear. This continues to cast significant uncertainty on severe probabilities through the first half of the extended forecast period. By early next week, mid-level ridging is expected to strengthen, forcing stronger flow aloft northward as the primary western trough begins to weaken. A second trough will stall over the West as the ridge continues to build. This should favor drier surface conditions while also limiting the overlap of buoyancy with stronger flow aloft. Severe potential appears limited beyond this weekend and into the first half of next week. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0356 AM CDT Wed Sep 10 2025 Valid 131200Z - 181200Z ...DISCUSSION... Severe potential in the extended forecast period will be tied to a shortwave trough and stronger southwesterly flow aloft emanating from the Rockies over the central US. Flow aloft will increase D4/Saturday as the upper trough begins to overspread the central US. Ascent from the trough will maintain a weak surface low and stationary front over the northern Plains and Upper Midwest. At the same time, a weak cold front will move eastward over the High Plains serving as a focus for thunderstorm development from the Dakotas and MN to the southern Plains each afternoon. Some isolated severe potential is apparent near the surface low/stalled front over the northern Plains and along the cold front farther south through the remainder of the weekend. However, model guidance varies widely on available moisture/buoyancy and the overlap with more robust vertical shear. This continues to cast significant uncertainty on severe probabilities through the first half of the extended forecast period. By early next week, mid-level ridging is expected to strengthen, forcing stronger flow aloft northward as the primary western trough begins to weaken. A second trough will stall over the West as the ridge continues to build. This should favor drier surface conditions while also limiting the overlap of buoyancy with stronger flow aloft. Severe potential appears limited beyond this weekend and into the first half of next week. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0356 AM CDT Wed Sep 10 2025 Valid 131200Z - 181200Z ...DISCUSSION... Severe potential in the extended forecast period will be tied to a shortwave trough and stronger southwesterly flow aloft emanating from the Rockies over the central US. Flow aloft will increase D4/Saturday as the upper trough begins to overspread the central US. Ascent from the trough will maintain a weak surface low and stationary front over the northern Plains and Upper Midwest. At the same time, a weak cold front will move eastward over the High Plains serving as a focus for thunderstorm development from the Dakotas and MN to the southern Plains each afternoon. Some isolated severe potential is apparent near the surface low/stalled front over the northern Plains and along the cold front farther south through the remainder of the weekend. However, model guidance varies widely on available moisture/buoyancy and the overlap with more robust vertical shear. This continues to cast significant uncertainty on severe probabilities through the first half of the extended forecast period. By early next week, mid-level ridging is expected to strengthen, forcing stronger flow aloft northward as the primary western trough begins to weaken. A second trough will stall over the West as the ridge continues to build. This should favor drier surface conditions while also limiting the overlap of buoyancy with stronger flow aloft. Severe potential appears limited beyond this weekend and into the first half of next week. Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0234 AM CDT Wed Sep 10 2025 Valid 121200Z - 131200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated storms are possible over parts of the Northern Plains and Upper Midwest with additional storms possible over the Rockies and Great Basin Friday. Severe potential is uncertain. ...Northern Plains and Upper Midwest... Shortwave ridging over the northern Plains and Upper Midwest is forecast to shift eastward Friday as weak troughing emerges from the Rockies. A modest increase in mid-level southwesterly flow will impinge upon rich low-level moisture near a weakening surface low and stalled warm front across the Dakotas and western MN. Low-level convergence near the low/front may serve as a focus for isolated thunderstorm development Friday afternoon and evening. Moderate MLCAPE around 2000 J/kg and steepening mid-level lapse rates could support a few stronger storms. Some enhancement of the mid-level flow may allow for a few storms to organize with some clustering and isolated strong outflow gusts. The primary uncertainty remains storm coverage with most guidance showing only sporadic convection through much of the day. An increase in convective coverage is possible overnight and into early Saturday as a 35-40 kt southerly low-level jet develops across the central Plains, bolstering low-level warm advection. Should this occur, one or more clusters of thunderstorms could propagate eastward along the warm front, potentially posing a risk for severe gusts. However, this is highly uncertain and with substantial model differences evident, no severe probabilities will be introduced. ...Intermountain West... Monsoon moisture is expected to linger over portions of the eastern Great Basin and central Rockies Friday ahead of a broad upper low. A shortwave trough within the southwesterly flow aloft will overspread the region near peak heating. The increase in ascent will support scattered thunderstorms over portions of the Intermountain West Friday afternoon and evening. While buoyancy will not be overly large (~500 J/kg of MLCAPE) and some remnant cloud cover/convection could overturn the air mass, increasingly strong southwesterly flow aloft could support a few stronger thunderstorms/clusters. With a fairly dry air mass in place, stronger downdrafts could be capable of isolated gusty winds given steep low-level lapse rates. ..Lyons.. 09/10/2025 Read more