Aggregator

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1213 AM CDT Thu Sep 05 2024 Valid 061200Z - 071200Z ...Synopsis... Isolated dry thunderstorms will be the primary fire weather concern for Friday across parts of the northern Sierra Nevada into southwest OR. Recent water-vapor imagery reveals a weak upper disturbance over the eastern Pacific on the fringe of the upper ridge over the western U.S. This feature is expected to drift east/northeast over the next 48 hours, reaching northern CA/southern OR by late afternoon/evening Friday. As this occurs, a modest influx of mid-level moisture and ascent-driven mid-level cooling over the northern Sierra Nevada and southern Cascades should support adequate buoyancy for isolated thunderstorms. Recent forecast soundings suggest that boundary layer conditions will be sufficiently dry for dry lightning strikes, which will pose a fire weather concern given the dry fuels over the region (ERCs generally at or above the 80th percentile). Thunderstorms will be most likely along and to the lee side of the northern Sierra Nevada and southern Cascades where orographic ascent will aid in convective initiation. Additionally, strengthening southwesterly mid-level flow should enhance downslope winds across northern CA into northwest NV. Areas of elevated fire weather conditions are possible (and will most likely occur within the dry-thunderstorm risk area, but ensemble confidence in the coverage and duration of these conditions is somewhat limited (around 30-40% probability for sustained elevated conditions based on latest ensemble guidance). ..Moore.. 09/05/2024 ...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 1212 AM CDT Thu Sep 05 2024 Valid 051200Z - 061200Z ...NO CRITICAL AREAS... ...Synopsis... Fire weather concerns will be limited for today across the country. 05 UTC surface observations show a cold front slowly migrating south across the Plains and the upper MS River Valley. This front is expected to reach the southern Plains by evening as surface high pressure builds across the northern CONUS. Breezy conditions are expected behind the front, but an influx of cooler air combined with cloud cover and isolated to scattered showers and thunderstorms limits fire weather concerns. Across the West, an upper ridge currently over the region will linger through the next 24 hours. This will promote mostly clear skies and dry conditions for the afternoon with RH values in the teens and low 20s common. Surface winds will remain relatively benign with the exception of mountainous areas of southern CA, the northern Cascades, and parts of central to southern UT. Any fire weather concerns across these regions should remain sufficiently localized to preclude the need for highlights. ..Moore.. 09/05/2024 ...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 1212 AM CDT Thu Sep 05 2024 Valid 051200Z - 061200Z ...NO CRITICAL AREAS... ...Synopsis... Fire weather concerns will be limited for today across the country. 05 UTC surface observations show a cold front slowly migrating south across the Plains and the upper MS River Valley. This front is expected to reach the southern Plains by evening as surface high pressure builds across the northern CONUS. Breezy conditions are expected behind the front, but an influx of cooler air combined with cloud cover and isolated to scattered showers and thunderstorms limits fire weather concerns. Across the West, an upper ridge currently over the region will linger through the next 24 hours. This will promote mostly clear skies and dry conditions for the afternoon with RH values in the teens and low 20s common. Surface winds will remain relatively benign with the exception of mountainous areas of southern CA, the northern Cascades, and parts of central to southern UT. Any fire weather concerns across these regions should remain sufficiently localized to preclude the need for highlights. ..Moore.. 09/05/2024 ...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 1212 AM CDT Thu Sep 05 2024 Valid 051200Z - 061200Z ...NO CRITICAL AREAS... ...Synopsis... Fire weather concerns will be limited for today across the country. 05 UTC surface observations show a cold front slowly migrating south across the Plains and the upper MS River Valley. This front is expected to reach the southern Plains by evening as surface high pressure builds across the northern CONUS. Breezy conditions are expected behind the front, but an influx of cooler air combined with cloud cover and isolated to scattered showers and thunderstorms limits fire weather concerns. Across the West, an upper ridge currently over the region will linger through the next 24 hours. This will promote mostly clear skies and dry conditions for the afternoon with RH values in the teens and low 20s common. Surface winds will remain relatively benign with the exception of mountainous areas of southern CA, the northern Cascades, and parts of central to southern UT. Any fire weather concerns across these regions should remain sufficiently localized to preclude the need for highlights. ..Moore.. 09/05/2024 ...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 1212 AM CDT Thu Sep 05 2024 Valid 051200Z - 061200Z ...NO CRITICAL AREAS... ...Synopsis... Fire weather concerns will be limited for today across the country. 05 UTC surface observations show a cold front slowly migrating south across the Plains and the upper MS River Valley. This front is expected to reach the southern Plains by evening as surface high pressure builds across the northern CONUS. Breezy conditions are expected behind the front, but an influx of cooler air combined with cloud cover and isolated to scattered showers and thunderstorms limits fire weather concerns. Across the West, an upper ridge currently over the region will linger through the next 24 hours. This will promote mostly clear skies and dry conditions for the afternoon with RH values in the teens and low 20s common. Surface winds will remain relatively benign with the exception of mountainous areas of southern CA, the northern Cascades, and parts of central to southern UT. Any fire weather concerns across these regions should remain sufficiently localized to preclude the need for highlights. ..Moore.. 09/05/2024 ...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 1212 AM CDT Thu Sep 05 2024 Valid 051200Z - 061200Z ...NO CRITICAL AREAS... ...Synopsis... Fire weather concerns will be limited for today across the country. 05 UTC surface observations show a cold front slowly migrating south across the Plains and the upper MS River Valley. This front is expected to reach the southern Plains by evening as surface high pressure builds across the northern CONUS. Breezy conditions are expected behind the front, but an influx of cooler air combined with cloud cover and isolated to scattered showers and thunderstorms limits fire weather concerns. Across the West, an upper ridge currently over the region will linger through the next 24 hours. This will promote mostly clear skies and dry conditions for the afternoon with RH values in the teens and low 20s common. Surface winds will remain relatively benign with the exception of mountainous areas of southern CA, the northern Cascades, and parts of central to southern UT. Any fire weather concerns across these regions should remain sufficiently localized to preclude the need for highlights. ..Moore.. 09/05/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

000
ABPZ20 KNHC 050515
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
1100 PM PDT Wed Sep 4 2024

For the eastern North Pacific...east of 140 degrees west longitude:

Offshore of Southwestern Mexico:
A broad area of low pressure is forecast to form early next week off
the coast of southern Mexico. Environmental conditions could support
some gradual development of this system thereafter while it moves
generally west-northwestward, roughly parallel to the coast of
southwestern Mexico.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 7 days...low...20 percent.

$$
Forecaster Reinhart

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0758 PM CDT Wed Sep 04 2024 Valid 050100Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PART OF THE CENTRAL HIGH PLAINS NORTHEASTWARD INTO THE UPPER MISSISSIPPI VALLEY... ...SUMMARY... Isolated severe storms capable of damaging wind gusts and hail will be possible this evening from parts of the central Rockies northeastward into the upper Mississippi Valley. ...Central Rockies/Central Plains/Upper Mississippi Valley... The latest water vapor imagery shows a positively-tilted upper-level trough over the north-central Rockies, with west-southwesterly mid-level flow over the northern Plains and upper Mississippi Valley. At the surface, a cold front is located from eastern Colorado northeastward into southwest Minnesota. Scattered thunderstorms are ongoing behind the front from Colorado and Wyoming eastward into the central High Plains. RAP analysis has weak instability in place across the central High Plains and central Rockies, with MLCAPE generally in the 250 to 500 J/kg range. Forecast soundings across this weakly unstable airmass this evening have 0-3 km shear mostly between 25 and 35 knots, with 850-500 mb lapse rates near 7 C/km. This environment should be enough to continue a marginal severe threat for a few more hours this evening. Hail and isolated severe gusts will be the primary threats. As the upper-level trough moves eastward this evening, large-scale ascent will overspread parts of the northern Plains and upper Mississippi Valley. Thunderstorms are expected to develop within and near a pocket of moderate instability over eastern South Dakota, northeastern Nebraska and southwest Minnesota. These storms could also be associated with a potential for marginally severe wind gusts and hail. The greatest threat should be with cells that develop near the front late this evening, where instability is expected to be the strongest. ..Broyles.. 09/05/2024 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0758 PM CDT Wed Sep 04 2024 Valid 050100Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PART OF THE CENTRAL HIGH PLAINS NORTHEASTWARD INTO THE UPPER MISSISSIPPI VALLEY... ...SUMMARY... Isolated severe storms capable of damaging wind gusts and hail will be possible this evening from parts of the central Rockies northeastward into the upper Mississippi Valley. ...Central Rockies/Central Plains/Upper Mississippi Valley... The latest water vapor imagery shows a positively-tilted upper-level trough over the north-central Rockies, with west-southwesterly mid-level flow over the northern Plains and upper Mississippi Valley. At the surface, a cold front is located from eastern Colorado northeastward into southwest Minnesota. Scattered thunderstorms are ongoing behind the front from Colorado and Wyoming eastward into the central High Plains. RAP analysis has weak instability in place across the central High Plains and central Rockies, with MLCAPE generally in the 250 to 500 J/kg range. Forecast soundings across this weakly unstable airmass this evening have 0-3 km shear mostly between 25 and 35 knots, with 850-500 mb lapse rates near 7 C/km. This environment should be enough to continue a marginal severe threat for a few more hours this evening. Hail and isolated severe gusts will be the primary threats. As the upper-level trough moves eastward this evening, large-scale ascent will overspread parts of the northern Plains and upper Mississippi Valley. Thunderstorms are expected to develop within and near a pocket of moderate instability over eastern South Dakota, northeastern Nebraska and southwest Minnesota. These storms could also be associated with a potential for marginally severe wind gusts and hail. The greatest threat should be with cells that develop near the front late this evening, where instability is expected to be the strongest. ..Broyles.. 09/05/2024 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0758 PM CDT Wed Sep 04 2024 Valid 050100Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PART OF THE CENTRAL HIGH PLAINS NORTHEASTWARD INTO THE UPPER MISSISSIPPI VALLEY... ...SUMMARY... Isolated severe storms capable of damaging wind gusts and hail will be possible this evening from parts of the central Rockies northeastward into the upper Mississippi Valley. ...Central Rockies/Central Plains/Upper Mississippi Valley... The latest water vapor imagery shows a positively-tilted upper-level trough over the north-central Rockies, with west-southwesterly mid-level flow over the northern Plains and upper Mississippi Valley. At the surface, a cold front is located from eastern Colorado northeastward into southwest Minnesota. Scattered thunderstorms are ongoing behind the front from Colorado and Wyoming eastward into the central High Plains. RAP analysis has weak instability in place across the central High Plains and central Rockies, with MLCAPE generally in the 250 to 500 J/kg range. Forecast soundings across this weakly unstable airmass this evening have 0-3 km shear mostly between 25 and 35 knots, with 850-500 mb lapse rates near 7 C/km. This environment should be enough to continue a marginal severe threat for a few more hours this evening. Hail and isolated severe gusts will be the primary threats. As the upper-level trough moves eastward this evening, large-scale ascent will overspread parts of the northern Plains and upper Mississippi Valley. Thunderstorms are expected to develop within and near a pocket of moderate instability over eastern South Dakota, northeastern Nebraska and southwest Minnesota. These storms could also be associated with a potential for marginally severe wind gusts and hail. The greatest threat should be with cells that develop near the front late this evening, where instability is expected to be the strongest. ..Broyles.. 09/05/2024 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0758 PM CDT Wed Sep 04 2024 Valid 050100Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PART OF THE CENTRAL HIGH PLAINS NORTHEASTWARD INTO THE UPPER MISSISSIPPI VALLEY... ...SUMMARY... Isolated severe storms capable of damaging wind gusts and hail will be possible this evening from parts of the central Rockies northeastward into the upper Mississippi Valley. ...Central Rockies/Central Plains/Upper Mississippi Valley... The latest water vapor imagery shows a positively-tilted upper-level trough over the north-central Rockies, with west-southwesterly mid-level flow over the northern Plains and upper Mississippi Valley. At the surface, a cold front is located from eastern Colorado northeastward into southwest Minnesota. Scattered thunderstorms are ongoing behind the front from Colorado and Wyoming eastward into the central High Plains. RAP analysis has weak instability in place across the central High Plains and central Rockies, with MLCAPE generally in the 250 to 500 J/kg range. Forecast soundings across this weakly unstable airmass this evening have 0-3 km shear mostly between 25 and 35 knots, with 850-500 mb lapse rates near 7 C/km. This environment should be enough to continue a marginal severe threat for a few more hours this evening. Hail and isolated severe gusts will be the primary threats. As the upper-level trough moves eastward this evening, large-scale ascent will overspread parts of the northern Plains and upper Mississippi Valley. Thunderstorms are expected to develop within and near a pocket of moderate instability over eastern South Dakota, northeastern Nebraska and southwest Minnesota. These storms could also be associated with a potential for marginally severe wind gusts and hail. The greatest threat should be with cells that develop near the front late this evening, where instability is expected to be the strongest. ..Broyles.. 09/05/2024 Read more

000
ABPZ20 KNHC 042326
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
500 PM PDT Wed Sep 4 2024

For the eastern North Pacific...east of 140 degrees west longitude:

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

$$
Forecaster Reinhart

No watches are valid as of Wed Sep 4 22:22:01 UTC 2024.

No Mesoscale Discussions are in effect as of Wed Sep 4 22:22:01 UTC 2024.

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0456 PM CDT Wed Sep 04 2024 Valid 061200Z - 121200Z High pressure will continue to build in across the western US D3/Friday through D4/Saturday, with a warming and drying trend. Thunderstorm activity will be minimal across the Southwest as Monsoonal moisture has gradually shifted southward. Temperatures across the west will climb to above normal, but winds will remain mostly light where fuels are the driest in the west. The aforementioned hot, dry, unstable conditions will lead to some increase in fire behavior. A return of isolated dry thunderstorm activity is expected beginning late D3/Friday and D4/Saturday across northern California into the Pacific Northwest as a trough approaches from the Pacific and precipitable water values steadily increase. Isolated dry thunder probabilities were included on D3/Friday across the Sierra into western Nevada and into south-central Oregon and northward into the Cascade Range in Oregon and Washington on D4/Saturday, where signal for thunderstorms is highest in multiple deterministic runs. Monsoonal moisture will slowly begin to return northward across the Southwest by D5/Sunday-D8/Wednesday. A few areas of isolated dry thunderstorms will be possible across northern Arizona into southern Utah. Fuels within this region remain seasonably wet with recent rainfall and as such no areas have been included at this time. Further warming and drying is expected through the early extended and status of fuels will be reevaluated for future outlooks. The Pacific trough will deepen and move inland by D6/Monday-D8 /Wednesday, bringing enhanced westerly flow across northern California, the Pacific Northwest, and into the Great Basin. This will lead to potential Elevated to Critical conditions, particularly on D7/Tuesday and D8/Wednesday. For now, confidence remains too low to include areas based on model agreement, fuels, and potential rainfall. ..Thornton.. 09/04/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0456 PM CDT Wed Sep 04 2024 Valid 061200Z - 121200Z High pressure will continue to build in across the western US D3/Friday through D4/Saturday, with a warming and drying trend. Thunderstorm activity will be minimal across the Southwest as Monsoonal moisture has gradually shifted southward. Temperatures across the west will climb to above normal, but winds will remain mostly light where fuels are the driest in the west. The aforementioned hot, dry, unstable conditions will lead to some increase in fire behavior. A return of isolated dry thunderstorm activity is expected beginning late D3/Friday and D4/Saturday across northern California into the Pacific Northwest as a trough approaches from the Pacific and precipitable water values steadily increase. Isolated dry thunder probabilities were included on D3/Friday across the Sierra into western Nevada and into south-central Oregon and northward into the Cascade Range in Oregon and Washington on D4/Saturday, where signal for thunderstorms is highest in multiple deterministic runs. Monsoonal moisture will slowly begin to return northward across the Southwest by D5/Sunday-D8/Wednesday. A few areas of isolated dry thunderstorms will be possible across northern Arizona into southern Utah. Fuels within this region remain seasonably wet with recent rainfall and as such no areas have been included at this time. Further warming and drying is expected through the early extended and status of fuels will be reevaluated for future outlooks. The Pacific trough will deepen and move inland by D6/Monday-D8 /Wednesday, bringing enhanced westerly flow across northern California, the Pacific Northwest, and into the Great Basin. This will lead to potential Elevated to Critical conditions, particularly on D7/Tuesday and D8/Wednesday. For now, confidence remains too low to include areas based on model agreement, fuels, and potential rainfall. ..Thornton.. 09/04/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0456 PM CDT Wed Sep 04 2024 Valid 061200Z - 121200Z High pressure will continue to build in across the western US D3/Friday through D4/Saturday, with a warming and drying trend. Thunderstorm activity will be minimal across the Southwest as Monsoonal moisture has gradually shifted southward. Temperatures across the west will climb to above normal, but winds will remain mostly light where fuels are the driest in the west. The aforementioned hot, dry, unstable conditions will lead to some increase in fire behavior. A return of isolated dry thunderstorm activity is expected beginning late D3/Friday and D4/Saturday across northern California into the Pacific Northwest as a trough approaches from the Pacific and precipitable water values steadily increase. Isolated dry thunder probabilities were included on D3/Friday across the Sierra into western Nevada and into south-central Oregon and northward into the Cascade Range in Oregon and Washington on D4/Saturday, where signal for thunderstorms is highest in multiple deterministic runs. Monsoonal moisture will slowly begin to return northward across the Southwest by D5/Sunday-D8/Wednesday. A few areas of isolated dry thunderstorms will be possible across northern Arizona into southern Utah. Fuels within this region remain seasonably wet with recent rainfall and as such no areas have been included at this time. Further warming and drying is expected through the early extended and status of fuels will be reevaluated for future outlooks. The Pacific trough will deepen and move inland by D6/Monday-D8 /Wednesday, bringing enhanced westerly flow across northern California, the Pacific Northwest, and into the Great Basin. This will lead to potential Elevated to Critical conditions, particularly on D7/Tuesday and D8/Wednesday. For now, confidence remains too low to include areas based on model agreement, fuels, and potential rainfall. ..Thornton.. 09/04/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0456 PM CDT Wed Sep 04 2024 Valid 061200Z - 121200Z High pressure will continue to build in across the western US D3/Friday through D4/Saturday, with a warming and drying trend. Thunderstorm activity will be minimal across the Southwest as Monsoonal moisture has gradually shifted southward. Temperatures across the west will climb to above normal, but winds will remain mostly light where fuels are the driest in the west. The aforementioned hot, dry, unstable conditions will lead to some increase in fire behavior. A return of isolated dry thunderstorm activity is expected beginning late D3/Friday and D4/Saturday across northern California into the Pacific Northwest as a trough approaches from the Pacific and precipitable water values steadily increase. Isolated dry thunder probabilities were included on D3/Friday across the Sierra into western Nevada and into south-central Oregon and northward into the Cascade Range in Oregon and Washington on D4/Saturday, where signal for thunderstorms is highest in multiple deterministic runs. Monsoonal moisture will slowly begin to return northward across the Southwest by D5/Sunday-D8/Wednesday. A few areas of isolated dry thunderstorms will be possible across northern Arizona into southern Utah. Fuels within this region remain seasonably wet with recent rainfall and as such no areas have been included at this time. Further warming and drying is expected through the early extended and status of fuels will be reevaluated for future outlooks. The Pacific trough will deepen and move inland by D6/Monday-D8 /Wednesday, bringing enhanced westerly flow across northern California, the Pacific Northwest, and into the Great Basin. This will lead to potential Elevated to Critical conditions, particularly on D7/Tuesday and D8/Wednesday. For now, confidence remains too low to include areas based on model agreement, fuels, and potential rainfall. ..Thornton.. 09/04/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Wed Sep 04 2024 Valid 042000Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL ROCKIES INTO THE NORTHERN/CENTRAL PLAINS AND UPPER MISSISSIPPI VALLEY... ...SUMMARY... Isolated strong to severe thunderstorms capable of gusty winds and hail may occur this afternoon and evening across parts of the central Rockies into the northern/central Plains and upper Mississippi Valley. ...20Z Update... The forecast remains on track, and no appreciable changes were made to the outlook with this update. Isolated thunderstorms are developing/spreading eastward across the central Rockies this afternoon -- ahead of a positively tilted midlevel trough moving across the region. The strongest storms will be capable of producing marginally severe hail and isolated severe gusts. For additional details, see MCD #2047. Across the central Plains into the Upper MS Valley, severe-thunderstorm potential is more uncertain along/behind the cold front this evening into the overnight hours. However, given the potential for isolated instances of severe hail and locally strong/damaging gusts, the Marginal Risk has been maintained across this area. Farther east, clusters of thunderstorms are tracking westward across the central Gulf Coast, in an environment characterized by 2+ inch PW and pockets of diurnal heating/boundary-layer destabilization. Given some banded convection here -- aided by enhanced low-level easterlies -- a couple water-loaded downbursts will be possible. Overall, the severe threat still appears too localized/marginal for 5-percent severe wind probabilities. ..Weinman.. 09/04/2024 .PREV DISCUSSION... /ISSUED 1124 AM CDT Wed Sep 04 2024/ ...Central Rockies into the central High Plains... Recent satellite imagery reveals a broad shortwave trough currently moving through southern ID and northern NV/UT. This shortwave trough and accompanying cold mid-level temperatures are forecast to continue eastward throughout the day, progressing across WY and northern CO. Modest buoyancy, fostered mainly by cooling mid-level temperatures, is anticipated across WY and adjacent parts of northern CO as the shortwave trough progresses through. Thunderstorm development is expected as the large-scale ascent attendant to the shortwave trough interacts with this buoyancy during the afternoon. Moderate mid-level westerlies will accompany this shortwave trough as well, with the resulting increase in vertical shear supporting the potential for a few more organized/persistent storms. Initially more cellular development across the higher terrain could pose a risk for isolated hail, particularly across south-central WY and north-central CO where the best overlap between the stronger shear and cold mid-level temperatures is expected. Damaging wind gusts are possible as well, particularly as the storms reach the lower elevations of central High Plains where a deeply mixed boundary layer will be in place. ...Central Plains into the Upper MS Valley... Recent surface analysis places a low over southeast ND, with weak troughing extending southwestward from this low in east-central CO. The primary cold front is west of this surface trough, extending from the low over southeast ND into more of northwest SD and adjacent northeast WY. The surface low is forecast to progress east-southeastward throughout the day, reaching south-central MN by late tonight. The attendant cold front is expected to push southward during the same period, progressing through much of NE by early Thursday morning. Warm mid-level temperatures should preclude thunderstorm development along the surface trough during the afternoon and evening. A few isolated storms are possible during the evening behind the front as the shortwave trough ejects out into the central Plains. Additional thunderstorm development is expected overnight/early Thursday morning across the Upper MS Valley, with some isolated hail possible within the strongest storms. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Wed Sep 04 2024 Valid 042000Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL ROCKIES INTO THE NORTHERN/CENTRAL PLAINS AND UPPER MISSISSIPPI VALLEY... ...SUMMARY... Isolated strong to severe thunderstorms capable of gusty winds and hail may occur this afternoon and evening across parts of the central Rockies into the northern/central Plains and upper Mississippi Valley. ...20Z Update... The forecast remains on track, and no appreciable changes were made to the outlook with this update. Isolated thunderstorms are developing/spreading eastward across the central Rockies this afternoon -- ahead of a positively tilted midlevel trough moving across the region. The strongest storms will be capable of producing marginally severe hail and isolated severe gusts. For additional details, see MCD #2047. Across the central Plains into the Upper MS Valley, severe-thunderstorm potential is more uncertain along/behind the cold front this evening into the overnight hours. However, given the potential for isolated instances of severe hail and locally strong/damaging gusts, the Marginal Risk has been maintained across this area. Farther east, clusters of thunderstorms are tracking westward across the central Gulf Coast, in an environment characterized by 2+ inch PW and pockets of diurnal heating/boundary-layer destabilization. Given some banded convection here -- aided by enhanced low-level easterlies -- a couple water-loaded downbursts will be possible. Overall, the severe threat still appears too localized/marginal for 5-percent severe wind probabilities. ..Weinman.. 09/04/2024 .PREV DISCUSSION... /ISSUED 1124 AM CDT Wed Sep 04 2024/ ...Central Rockies into the central High Plains... Recent satellite imagery reveals a broad shortwave trough currently moving through southern ID and northern NV/UT. This shortwave trough and accompanying cold mid-level temperatures are forecast to continue eastward throughout the day, progressing across WY and northern CO. Modest buoyancy, fostered mainly by cooling mid-level temperatures, is anticipated across WY and adjacent parts of northern CO as the shortwave trough progresses through. Thunderstorm development is expected as the large-scale ascent attendant to the shortwave trough interacts with this buoyancy during the afternoon. Moderate mid-level westerlies will accompany this shortwave trough as well, with the resulting increase in vertical shear supporting the potential for a few more organized/persistent storms. Initially more cellular development across the higher terrain could pose a risk for isolated hail, particularly across south-central WY and north-central CO where the best overlap between the stronger shear and cold mid-level temperatures is expected. Damaging wind gusts are possible as well, particularly as the storms reach the lower elevations of central High Plains where a deeply mixed boundary layer will be in place. ...Central Plains into the Upper MS Valley... Recent surface analysis places a low over southeast ND, with weak troughing extending southwestward from this low in east-central CO. The primary cold front is west of this surface trough, extending from the low over southeast ND into more of northwest SD and adjacent northeast WY. The surface low is forecast to progress east-southeastward throughout the day, reaching south-central MN by late tonight. The attendant cold front is expected to push southward during the same period, progressing through much of NE by early Thursday morning. Warm mid-level temperatures should preclude thunderstorm development along the surface trough during the afternoon and evening. A few isolated storms are possible during the evening behind the front as the shortwave trough ejects out into the central Plains. Additional thunderstorm development is expected overnight/early Thursday morning across the Upper MS Valley, with some isolated hail possible within the strongest storms. Read more