Aggregator

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0755 AM CDT Tue Jul 23 2024 Valid 231300Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE MID-ATLANTIC STATES AND CAROLINAS... ...SUMMARY... Today's overall risk for organized severe thunderstorms is expected to remain relatively low, but a few severe storms may occur across the Mid-Atlantic States/Carolinas. ...Mid-Atlantic/Carolinas/Southeast States... The air mass over the region will remain very moist with Precipitable Water values in excess of 2 inches, contributing to a moderately unstable and minimally inhibited boundary layer this afternoon. A modest increase in mid-level flow may occur today from the southern Appalachians northeast across the mid-Atlantic, but low-level winds will remain weak. While locally heavy rainfall will be the most common hazard regionally, wet microbursts could cause a few instances of localized wind damage this afternoon, with a somewhat greater potential across parts of North Carolina and Virginia. ...Midwest... Thunderstorms are expected to redevelop along the northern front from southern Wisconsin across Iowa and southern Minnesota this afternoon, with the potential for multiple rounds of storms in some locations. Moderate buoyancy should be in place near the front, however deep-layer shear should generally remain at 25-30 kt (or less) for much of the day. Some risk for hail and gusty winds will exist with any stronger storm, but will defer any potential introduction of low severe probabilities to subsequent outlooks. ...Arizona/Lower Colorado River Valley... Thunderstorms are expected to develop over the Mogollon Rim of Arizona again this afternoon, with relatively weak northeast mid-level flow steering storms southwest into the lower elevations. Despite very hot temperatures and a deep/well-mixed boundary layer, overall confidence that storms will cluster and produce more than localized strong/damaging gusts remains too low to introduce severe probabilities. ..Guyer.. 07/23/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0755 AM CDT Tue Jul 23 2024 Valid 231300Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE MID-ATLANTIC STATES AND CAROLINAS... ...SUMMARY... Today's overall risk for organized severe thunderstorms is expected to remain relatively low, but a few severe storms may occur across the Mid-Atlantic States/Carolinas. ...Mid-Atlantic/Carolinas/Southeast States... The air mass over the region will remain very moist with Precipitable Water values in excess of 2 inches, contributing to a moderately unstable and minimally inhibited boundary layer this afternoon. A modest increase in mid-level flow may occur today from the southern Appalachians northeast across the mid-Atlantic, but low-level winds will remain weak. While locally heavy rainfall will be the most common hazard regionally, wet microbursts could cause a few instances of localized wind damage this afternoon, with a somewhat greater potential across parts of North Carolina and Virginia. ...Midwest... Thunderstorms are expected to redevelop along the northern front from southern Wisconsin across Iowa and southern Minnesota this afternoon, with the potential for multiple rounds of storms in some locations. Moderate buoyancy should be in place near the front, however deep-layer shear should generally remain at 25-30 kt (or less) for much of the day. Some risk for hail and gusty winds will exist with any stronger storm, but will defer any potential introduction of low severe probabilities to subsequent outlooks. ...Arizona/Lower Colorado River Valley... Thunderstorms are expected to develop over the Mogollon Rim of Arizona again this afternoon, with relatively weak northeast mid-level flow steering storms southwest into the lower elevations. Despite very hot temperatures and a deep/well-mixed boundary layer, overall confidence that storms will cluster and produce more than localized strong/damaging gusts remains too low to introduce severe probabilities. ..Guyer.. 07/23/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0755 AM CDT Tue Jul 23 2024 Valid 231300Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE MID-ATLANTIC STATES AND CAROLINAS... ...SUMMARY... Today's overall risk for organized severe thunderstorms is expected to remain relatively low, but a few severe storms may occur across the Mid-Atlantic States/Carolinas. ...Mid-Atlantic/Carolinas/Southeast States... The air mass over the region will remain very moist with Precipitable Water values in excess of 2 inches, contributing to a moderately unstable and minimally inhibited boundary layer this afternoon. A modest increase in mid-level flow may occur today from the southern Appalachians northeast across the mid-Atlantic, but low-level winds will remain weak. While locally heavy rainfall will be the most common hazard regionally, wet microbursts could cause a few instances of localized wind damage this afternoon, with a somewhat greater potential across parts of North Carolina and Virginia. ...Midwest... Thunderstorms are expected to redevelop along the northern front from southern Wisconsin across Iowa and southern Minnesota this afternoon, with the potential for multiple rounds of storms in some locations. Moderate buoyancy should be in place near the front, however deep-layer shear should generally remain at 25-30 kt (or less) for much of the day. Some risk for hail and gusty winds will exist with any stronger storm, but will defer any potential introduction of low severe probabilities to subsequent outlooks. ...Arizona/Lower Colorado River Valley... Thunderstorms are expected to develop over the Mogollon Rim of Arizona again this afternoon, with relatively weak northeast mid-level flow steering storms southwest into the lower elevations. Despite very hot temperatures and a deep/well-mixed boundary layer, overall confidence that storms will cluster and produce more than localized strong/damaging gusts remains too low to introduce severe probabilities. ..Guyer.. 07/23/2024 Read more

509
ABPZ20 KNHC 231135
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
500 AM PDT Tue Jul 23 2024

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

Offshore Southwestern Mexico:
Showers and thunderstorms associated with an area of low pressure
located a few hundred miles south-southwest of Manzanillo, Mexico,
have become slightly better organized since yesterday. Environmental
conditions appear favorable for slow development over the next
couple of days while the disturbance moves generally
west-northwestward, remaining offshore of southwestern Mexico.
* Formation chance through 48 hours...low...30 percent.
* Formation chance through 7 days...low...30 percent.

Central and Western East Pacific:
A tropical wave located several hundred miles south-southwest of the
southern tip of the Baja California Peninsula is producing
disorganized shower and thunderstorm activity. Environmental
conditions appear only marginally conducive for some slight
development of this system over the next few days while it moves
westward to west-northwestward around 10 mph across the central
and western portions of the basin.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 7 days...low...20 percent.

$$
Forecaster Hagen/Berg

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0346 AM CDT Tue Jul 23 2024 Valid 261200Z - 311200Z ...DISCUSSION... Upper ridging will spread across parts of the Plains and eastern states, while the subtropical high develops westward over the southern tier of the U.S. during the Day 4-8/Fri-Tue period. This will suppress severe thunderstorm potential for much of the CONUS. The exception will be a potentially more active period for parts of the northern Plains into the Upper Midwest due to a series of upper shortwave troughs migrating across the Canadian Prairies and parts of the northern Plains/Upper Midwest through the forecast period. Surface high pressure over the Great Lakes and periodic surface low development over the northern High Plains will maintain a baroclinic zone over the Upper Midwest. As a result, southerly low-level flow will keep a seasonally moist airmass in place across the eastern Dakotas and Mid-MO Valley east to the Mid/Upper MS Valley. Some severe thunderstorm potential could develop around Day 4 Fri as the first upper shortwave trough moves across the Canadian Prairies. However, stronger vertical shear and large scale ascent will be focused north of the international border. Another weaker, but further south shortwave trough will traverse the northern Plains vicinity on Day 6/Sun before a somewhat stronger wave migrates through westerly flow toward Day 8/Tue. While various forecast guidance generally depicts this more progressive northern stream pattern, details in timing of each wave, as well as differences in the strength of the central U.S. upper ridge/subtropical high vary greatly. As a result, confidence is too low to include 15 percent probabilities at this time. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0346 AM CDT Tue Jul 23 2024 Valid 261200Z - 311200Z ...DISCUSSION... Upper ridging will spread across parts of the Plains and eastern states, while the subtropical high develops westward over the southern tier of the U.S. during the Day 4-8/Fri-Tue period. This will suppress severe thunderstorm potential for much of the CONUS. The exception will be a potentially more active period for parts of the northern Plains into the Upper Midwest due to a series of upper shortwave troughs migrating across the Canadian Prairies and parts of the northern Plains/Upper Midwest through the forecast period. Surface high pressure over the Great Lakes and periodic surface low development over the northern High Plains will maintain a baroclinic zone over the Upper Midwest. As a result, southerly low-level flow will keep a seasonally moist airmass in place across the eastern Dakotas and Mid-MO Valley east to the Mid/Upper MS Valley. Some severe thunderstorm potential could develop around Day 4 Fri as the first upper shortwave trough moves across the Canadian Prairies. However, stronger vertical shear and large scale ascent will be focused north of the international border. Another weaker, but further south shortwave trough will traverse the northern Plains vicinity on Day 6/Sun before a somewhat stronger wave migrates through westerly flow toward Day 8/Tue. While various forecast guidance generally depicts this more progressive northern stream pattern, details in timing of each wave, as well as differences in the strength of the central U.S. upper ridge/subtropical high vary greatly. As a result, confidence is too low to include 15 percent probabilities at this time. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0346 AM CDT Tue Jul 23 2024 Valid 261200Z - 311200Z ...DISCUSSION... Upper ridging will spread across parts of the Plains and eastern states, while the subtropical high develops westward over the southern tier of the U.S. during the Day 4-8/Fri-Tue period. This will suppress severe thunderstorm potential for much of the CONUS. The exception will be a potentially more active period for parts of the northern Plains into the Upper Midwest due to a series of upper shortwave troughs migrating across the Canadian Prairies and parts of the northern Plains/Upper Midwest through the forecast period. Surface high pressure over the Great Lakes and periodic surface low development over the northern High Plains will maintain a baroclinic zone over the Upper Midwest. As a result, southerly low-level flow will keep a seasonally moist airmass in place across the eastern Dakotas and Mid-MO Valley east to the Mid/Upper MS Valley. Some severe thunderstorm potential could develop around Day 4 Fri as the first upper shortwave trough moves across the Canadian Prairies. However, stronger vertical shear and large scale ascent will be focused north of the international border. Another weaker, but further south shortwave trough will traverse the northern Plains vicinity on Day 6/Sun before a somewhat stronger wave migrates through westerly flow toward Day 8/Tue. While various forecast guidance generally depicts this more progressive northern stream pattern, details in timing of each wave, as well as differences in the strength of the central U.S. upper ridge/subtropical high vary greatly. As a result, confidence is too low to include 15 percent probabilities at this time. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0346 AM CDT Tue Jul 23 2024 Valid 261200Z - 311200Z ...DISCUSSION... Upper ridging will spread across parts of the Plains and eastern states, while the subtropical high develops westward over the southern tier of the U.S. during the Day 4-8/Fri-Tue period. This will suppress severe thunderstorm potential for much of the CONUS. The exception will be a potentially more active period for parts of the northern Plains into the Upper Midwest due to a series of upper shortwave troughs migrating across the Canadian Prairies and parts of the northern Plains/Upper Midwest through the forecast period. Surface high pressure over the Great Lakes and periodic surface low development over the northern High Plains will maintain a baroclinic zone over the Upper Midwest. As a result, southerly low-level flow will keep a seasonally moist airmass in place across the eastern Dakotas and Mid-MO Valley east to the Mid/Upper MS Valley. Some severe thunderstorm potential could develop around Day 4 Fri as the first upper shortwave trough moves across the Canadian Prairies. However, stronger vertical shear and large scale ascent will be focused north of the international border. Another weaker, but further south shortwave trough will traverse the northern Plains vicinity on Day 6/Sun before a somewhat stronger wave migrates through westerly flow toward Day 8/Tue. While various forecast guidance generally depicts this more progressive northern stream pattern, details in timing of each wave, as well as differences in the strength of the central U.S. upper ridge/subtropical high vary greatly. As a result, confidence is too low to include 15 percent probabilities at this time. Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0202 AM CDT Tue Jul 23 2024 Valid 251200Z - 261200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorm potential appears low on Thursday. ...Synopsis... An upper trough over the lower Great Lakes and Ohio Valley vicinity will shift east over the Northeast/Atlantic coast on Thursday. At the same time, an upper shortwave trough over the Pacific Northwest will track east near the international border and northern Rockies. This will push the upper ridge oriented from the central Rockies to northern Plains east toward the Upper Midwest. A cold front will develop south and east across the Ohio Valley and the Northeast. Ongoing showers and widespread cloudiness will mute destabilization ahead of the front across the Northeast. While somewhat stronger destabilization is possible across parts of the lower Ohio Valley, vertical shear will be weak, limiting potential for organized severe storms. Further across parts of central/eastern MT, 50s F dewpoints and steep midlevel lapse rates will foster MLCAPE values up to 1000 J/kg. Strong heating and increasing ascent with the approach of the upper trough will allow for scattered thunderstorm development over higher terrain during the afternoon. Vertical shear will be modest, but deep mixing and inverted-v sub-cloud thermodynamic profiles suggest gusty outflow winds will be possible. A cold front will sweep across the region during the evening/overnight, but increasing inhibition with eastward extent will likely limit severe potential. ..Leitman.. 07/23/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0202 AM CDT Tue Jul 23 2024 Valid 251200Z - 261200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorm potential appears low on Thursday. ...Synopsis... An upper trough over the lower Great Lakes and Ohio Valley vicinity will shift east over the Northeast/Atlantic coast on Thursday. At the same time, an upper shortwave trough over the Pacific Northwest will track east near the international border and northern Rockies. This will push the upper ridge oriented from the central Rockies to northern Plains east toward the Upper Midwest. A cold front will develop south and east across the Ohio Valley and the Northeast. Ongoing showers and widespread cloudiness will mute destabilization ahead of the front across the Northeast. While somewhat stronger destabilization is possible across parts of the lower Ohio Valley, vertical shear will be weak, limiting potential for organized severe storms. Further across parts of central/eastern MT, 50s F dewpoints and steep midlevel lapse rates will foster MLCAPE values up to 1000 J/kg. Strong heating and increasing ascent with the approach of the upper trough will allow for scattered thunderstorm development over higher terrain during the afternoon. Vertical shear will be modest, but deep mixing and inverted-v sub-cloud thermodynamic profiles suggest gusty outflow winds will be possible. A cold front will sweep across the region during the evening/overnight, but increasing inhibition with eastward extent will likely limit severe potential. ..Leitman.. 07/23/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0202 AM CDT Tue Jul 23 2024 Valid 251200Z - 261200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorm potential appears low on Thursday. ...Synopsis... An upper trough over the lower Great Lakes and Ohio Valley vicinity will shift east over the Northeast/Atlantic coast on Thursday. At the same time, an upper shortwave trough over the Pacific Northwest will track east near the international border and northern Rockies. This will push the upper ridge oriented from the central Rockies to northern Plains east toward the Upper Midwest. A cold front will develop south and east across the Ohio Valley and the Northeast. Ongoing showers and widespread cloudiness will mute destabilization ahead of the front across the Northeast. While somewhat stronger destabilization is possible across parts of the lower Ohio Valley, vertical shear will be weak, limiting potential for organized severe storms. Further across parts of central/eastern MT, 50s F dewpoints and steep midlevel lapse rates will foster MLCAPE values up to 1000 J/kg. Strong heating and increasing ascent with the approach of the upper trough will allow for scattered thunderstorm development over higher terrain during the afternoon. Vertical shear will be modest, but deep mixing and inverted-v sub-cloud thermodynamic profiles suggest gusty outflow winds will be possible. A cold front will sweep across the region during the evening/overnight, but increasing inhibition with eastward extent will likely limit severe potential. ..Leitman.. 07/23/2024 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0201 AM CDT Tue Jul 23 2024 Valid 241200Z - 251200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF EASTERN OREGON...IDAHO AND WESTERN MONTANA... ...Synopsis... An upper ridge over the Rockies will gradually break down under the influence of a deepening Pacific trough entrenched over the Northwest. Strong mid-level flow moving onshore will aid in mid-level destabilization, supporting scattered to widespread thunderstorms and the potential for significant lightning Wed afternoon and evening. Dry downslope winds are also possible in the lee of the Cascades supporting elevated fire-weather potential. ...Northern Great Basin Northwest and the northern Rockies... A widespread and potentially significant lightning event appears possible over parts of the Northwest and northern Rockies Wed and Wed night. As the upper trough over the northwest continues to deepen, weak height falls and stronger flow aloft will gradually overspread the Intermountain West. Diurnal heating with increasing mid-level moisture (PWATs of 0.8-1 in) will support elevated buoyancy atop deep and well-mixed boundary layers. In addition to the very dry sub-cloud layer, mean storm motions of 35-40 kt suggest poor to very poor precipitation efficiency. Scattered thunderstorms appear likely by early to mid afternoon ahead of a weak cold front and across the higher terrain of eastern OR, central ID and west-central MT. Storm coverage should gradually increase through the afternoon and evening as storms move east/northeast into the northern Rockies. Scattered to numerous cloud to ground lightning strikes, and occasional strong downdrafts will be possible over areas of very dry fuels, warranting the introduction of Critical Dry Thunder probabilities. In addition to the Critical risk for lightning, increasing flow aloft twill support gusty downslope winds and low RH in the lee of the Cascades. Very warm temperatures and wind gusts of 15-25 mph will overlap with RH below 20% across the western Columbia Basin and Cascade Gaps, as well as across western MT. With numerous ongoing fires and robust fuels, elevated to locally critical fire-weather conditions are expected across parts of the Pacific Northwest and northern Rockies Wed. ..Lyons.. 07/23/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0201 AM CDT Tue Jul 23 2024 Valid 241200Z - 251200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF EASTERN OREGON...IDAHO AND WESTERN MONTANA... ...Synopsis... An upper ridge over the Rockies will gradually break down under the influence of a deepening Pacific trough entrenched over the Northwest. Strong mid-level flow moving onshore will aid in mid-level destabilization, supporting scattered to widespread thunderstorms and the potential for significant lightning Wed afternoon and evening. Dry downslope winds are also possible in the lee of the Cascades supporting elevated fire-weather potential. ...Northern Great Basin Northwest and the northern Rockies... A widespread and potentially significant lightning event appears possible over parts of the Northwest and northern Rockies Wed and Wed night. As the upper trough over the northwest continues to deepen, weak height falls and stronger flow aloft will gradually overspread the Intermountain West. Diurnal heating with increasing mid-level moisture (PWATs of 0.8-1 in) will support elevated buoyancy atop deep and well-mixed boundary layers. In addition to the very dry sub-cloud layer, mean storm motions of 35-40 kt suggest poor to very poor precipitation efficiency. Scattered thunderstorms appear likely by early to mid afternoon ahead of a weak cold front and across the higher terrain of eastern OR, central ID and west-central MT. Storm coverage should gradually increase through the afternoon and evening as storms move east/northeast into the northern Rockies. Scattered to numerous cloud to ground lightning strikes, and occasional strong downdrafts will be possible over areas of very dry fuels, warranting the introduction of Critical Dry Thunder probabilities. In addition to the Critical risk for lightning, increasing flow aloft twill support gusty downslope winds and low RH in the lee of the Cascades. Very warm temperatures and wind gusts of 15-25 mph will overlap with RH below 20% across the western Columbia Basin and Cascade Gaps, as well as across western MT. With numerous ongoing fires and robust fuels, elevated to locally critical fire-weather conditions are expected across parts of the Pacific Northwest and northern Rockies Wed. ..Lyons.. 07/23/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0201 AM CDT Tue Jul 23 2024 Valid 241200Z - 251200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF EASTERN OREGON...IDAHO AND WESTERN MONTANA... ...Synopsis... An upper ridge over the Rockies will gradually break down under the influence of a deepening Pacific trough entrenched over the Northwest. Strong mid-level flow moving onshore will aid in mid-level destabilization, supporting scattered to widespread thunderstorms and the potential for significant lightning Wed afternoon and evening. Dry downslope winds are also possible in the lee of the Cascades supporting elevated fire-weather potential. ...Northern Great Basin Northwest and the northern Rockies... A widespread and potentially significant lightning event appears possible over parts of the Northwest and northern Rockies Wed and Wed night. As the upper trough over the northwest continues to deepen, weak height falls and stronger flow aloft will gradually overspread the Intermountain West. Diurnal heating with increasing mid-level moisture (PWATs of 0.8-1 in) will support elevated buoyancy atop deep and well-mixed boundary layers. In addition to the very dry sub-cloud layer, mean storm motions of 35-40 kt suggest poor to very poor precipitation efficiency. Scattered thunderstorms appear likely by early to mid afternoon ahead of a weak cold front and across the higher terrain of eastern OR, central ID and west-central MT. Storm coverage should gradually increase through the afternoon and evening as storms move east/northeast into the northern Rockies. Scattered to numerous cloud to ground lightning strikes, and occasional strong downdrafts will be possible over areas of very dry fuels, warranting the introduction of Critical Dry Thunder probabilities. In addition to the Critical risk for lightning, increasing flow aloft twill support gusty downslope winds and low RH in the lee of the Cascades. Very warm temperatures and wind gusts of 15-25 mph will overlap with RH below 20% across the western Columbia Basin and Cascade Gaps, as well as across western MT. With numerous ongoing fires and robust fuels, elevated to locally critical fire-weather conditions are expected across parts of the Pacific Northwest and northern Rockies Wed. ..Lyons.. 07/23/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0201 AM CDT Tue Jul 23 2024 Valid 241200Z - 251200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF EASTERN OREGON...IDAHO AND WESTERN MONTANA... ...Synopsis... An upper ridge over the Rockies will gradually break down under the influence of a deepening Pacific trough entrenched over the Northwest. Strong mid-level flow moving onshore will aid in mid-level destabilization, supporting scattered to widespread thunderstorms and the potential for significant lightning Wed afternoon and evening. Dry downslope winds are also possible in the lee of the Cascades supporting elevated fire-weather potential. ...Northern Great Basin Northwest and the northern Rockies... A widespread and potentially significant lightning event appears possible over parts of the Northwest and northern Rockies Wed and Wed night. As the upper trough over the northwest continues to deepen, weak height falls and stronger flow aloft will gradually overspread the Intermountain West. Diurnal heating with increasing mid-level moisture (PWATs of 0.8-1 in) will support elevated buoyancy atop deep and well-mixed boundary layers. In addition to the very dry sub-cloud layer, mean storm motions of 35-40 kt suggest poor to very poor precipitation efficiency. Scattered thunderstorms appear likely by early to mid afternoon ahead of a weak cold front and across the higher terrain of eastern OR, central ID and west-central MT. Storm coverage should gradually increase through the afternoon and evening as storms move east/northeast into the northern Rockies. Scattered to numerous cloud to ground lightning strikes, and occasional strong downdrafts will be possible over areas of very dry fuels, warranting the introduction of Critical Dry Thunder probabilities. In addition to the Critical risk for lightning, increasing flow aloft twill support gusty downslope winds and low RH in the lee of the Cascades. Very warm temperatures and wind gusts of 15-25 mph will overlap with RH below 20% across the western Columbia Basin and Cascade Gaps, as well as across western MT. With numerous ongoing fires and robust fuels, elevated to locally critical fire-weather conditions are expected across parts of the Pacific Northwest and northern Rockies Wed. ..Lyons.. 07/23/2024 ...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 0159 AM CDT Tue Jul 23 2024 Valid 231200Z - 241200Z ...Synopsis... A broad upper trough over the Northwest will remain in place west of a weakening upper ridge centered across the northern Rockies. Stronger flow aloft will gradually overspread the Northwest and northern Rockies through the week. Isolated dry thunderstorms and gusty downslope winds will promote elevated fire-weather potential today and tonight. ...Northwest and northern Rockies... Lingering mid-level moisture ahead of the consolidating Pacific trough will again support the risk for thunderstorms across the Northwest and northern Rockies this afternoon and evening. While weaker than previous days, subtle ascent and diurnal heating over the terrain should allow for isolated storms to develop across parts of the northern Great Basin and Northwest by early afternoon. Low precipitation efficiency, owing to PWATs under 1 inch, and low surface RH will support the risk for lightning with little to no wetting rainfall. With area fuels still receptive to ignitions, IsoDryT probabilities have been maintained. West/southwest flow aloft is forecast to increase over the northern Rockies and Cascade Gaps ahead of the trough. This may promote several hours of gusty downslope winds across parts of eastern ID and western MT. Model guidance shows surface winds of 15-25 mph overlapping with RH values below 25%. This, along with the increase in lightning and numerous ongoing fires, will support the potential for elevated fire-weather conditions this afternoon. ..Lyons.. 07/23/2024 ...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 0159 AM CDT Tue Jul 23 2024 Valid 231200Z - 241200Z ...Synopsis... A broad upper trough over the Northwest will remain in place west of a weakening upper ridge centered across the northern Rockies. Stronger flow aloft will gradually overspread the Northwest and northern Rockies through the week. Isolated dry thunderstorms and gusty downslope winds will promote elevated fire-weather potential today and tonight. ...Northwest and northern Rockies... Lingering mid-level moisture ahead of the consolidating Pacific trough will again support the risk for thunderstorms across the Northwest and northern Rockies this afternoon and evening. While weaker than previous days, subtle ascent and diurnal heating over the terrain should allow for isolated storms to develop across parts of the northern Great Basin and Northwest by early afternoon. Low precipitation efficiency, owing to PWATs under 1 inch, and low surface RH will support the risk for lightning with little to no wetting rainfall. With area fuels still receptive to ignitions, IsoDryT probabilities have been maintained. West/southwest flow aloft is forecast to increase over the northern Rockies and Cascade Gaps ahead of the trough. This may promote several hours of gusty downslope winds across parts of eastern ID and western MT. Model guidance shows surface winds of 15-25 mph overlapping with RH values below 25%. This, along with the increase in lightning and numerous ongoing fires, will support the potential for elevated fire-weather conditions this afternoon. ..Lyons.. 07/23/2024 ...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 0159 AM CDT Tue Jul 23 2024 Valid 231200Z - 241200Z ...Synopsis... A broad upper trough over the Northwest will remain in place west of a weakening upper ridge centered across the northern Rockies. Stronger flow aloft will gradually overspread the Northwest and northern Rockies through the week. Isolated dry thunderstorms and gusty downslope winds will promote elevated fire-weather potential today and tonight. ...Northwest and northern Rockies... Lingering mid-level moisture ahead of the consolidating Pacific trough will again support the risk for thunderstorms across the Northwest and northern Rockies this afternoon and evening. While weaker than previous days, subtle ascent and diurnal heating over the terrain should allow for isolated storms to develop across parts of the northern Great Basin and Northwest by early afternoon. Low precipitation efficiency, owing to PWATs under 1 inch, and low surface RH will support the risk for lightning with little to no wetting rainfall. With area fuels still receptive to ignitions, IsoDryT probabilities have been maintained. West/southwest flow aloft is forecast to increase over the northern Rockies and Cascade Gaps ahead of the trough. This may promote several hours of gusty downslope winds across parts of eastern ID and western MT. Model guidance shows surface winds of 15-25 mph overlapping with RH values below 25%. This, along with the increase in lightning and numerous ongoing fires, will support the potential for elevated fire-weather conditions this afternoon. ..Lyons.. 07/23/2024 ...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 0159 AM CDT Tue Jul 23 2024 Valid 231200Z - 241200Z ...Synopsis... A broad upper trough over the Northwest will remain in place west of a weakening upper ridge centered across the northern Rockies. Stronger flow aloft will gradually overspread the Northwest and northern Rockies through the week. Isolated dry thunderstorms and gusty downslope winds will promote elevated fire-weather potential today and tonight. ...Northwest and northern Rockies... Lingering mid-level moisture ahead of the consolidating Pacific trough will again support the risk for thunderstorms across the Northwest and northern Rockies this afternoon and evening. While weaker than previous days, subtle ascent and diurnal heating over the terrain should allow for isolated storms to develop across parts of the northern Great Basin and Northwest by early afternoon. Low precipitation efficiency, owing to PWATs under 1 inch, and low surface RH will support the risk for lightning with little to no wetting rainfall. With area fuels still receptive to ignitions, IsoDryT probabilities have been maintained. West/southwest flow aloft is forecast to increase over the northern Rockies and Cascade Gaps ahead of the trough. This may promote several hours of gusty downslope winds across parts of eastern ID and western MT. Model guidance shows surface winds of 15-25 mph overlapping with RH values below 25%. This, along with the increase in lightning and numerous ongoing fires, will support the potential for elevated fire-weather conditions this afternoon. ..Lyons.. 07/23/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1224 AM CDT Tue Jul 23 2024 Valid 241200Z - 251200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF NORTHERN OHIO AND PENNSYLVANIA INTO NEW YORK... ...SUMMARY... Isolated strong to severe thunderstorms may produce damaging gusts across parts of northern Ohio and Pennsylvania into New York Wednesday afternoon and evening. ...Synopsis... An upper shortwave trough over the upper Great Lakes will develop eastward toward the upper Ohio Valley/lower Great Lakes vicinity on Wednesday. At the same time, the sub-tropical high over the western Atlantic will scoot westward toward the Mid-Atlantic and Southeast. This will result in an increasing/tightening height gradient across the Northeast as the upper trough develops east, and southwesterly mid/upper flow will increase from the Ohio Valley into the Mid-Atlantic and Northeast. Further west, an upper shortwave trough will develop east/southeast over the Pacific Northwest and northern Rockies, while an upper anticyclone persists over the Southwest. As the Pacific Northwest trough moves east, an upper ridge will overspread the central Rockies to the northern Plains. At the surface, a weak low will track northeast from the Lake Huron vicinity into southern Quebec. A trailing cold front will sag south/southeast across northern IL/IN/OH/PA and western NY during the afternoon and into the overnight hours. Meanwhile, a surface trough will extend southwest across the Chesapeake Bay vicinity into central NC. A moist airmass will be in place ahead of the surface cold front and near the surface trough, aiding in at least weak to moderate destabilization. These boundaries also will focus thunderstorm potential during the afternoon and evening hours. Further west, a baroclinic zone will exist over the northern Plains as a surface low deepens over the Canadian Prairies and high pressure builds over the upper Great Lakes. South/southeasterly low-level flow will allow for 60s F dewpoints across central/eastern portions of the Dakotas. However, capping within the amplifying upper ridge will likely preclude thunderstorm development. ...Northern OH/PA into NY... Increasing mid/upper-level southwesterly flow will support around 30-35 kt effective shear magnitudes by afternoon. Midlevel lapse rates will remain modest, but heating into the 80s and dewpoints in the mid/upper 60s F will allow for MLCAPE as high as 1500 J/kg. Stronger height falls will likely not occur until around/after 00z, somewhat misaligned with peak heating. Nevertheless, increasing vertical shear and modest large-scale ascent, coupled with the approaching cold front should support at least isolated to scattered thunderstorm development during the afternoon. Elongated hodographs and modest vertically veering wind profiles suggest organized cells, with perhaps transient supercell characteristics, will be possible. Steepening low-level lapse rates will support sporadic strong/locally damaging gusts. A couple of the strongest cells may produce marginal hail. ...Southeast VA into central/eastern NC... Thunderstorms are expected to develop within a very moist and unstable airmass Wednesday afternoon. While midlevel flow will gradually increase, vertical shear will remain marginal for organized convection, especially until after 00z. Given the high PW/moderately unstable airmass, a wet microburst or two will be possible. However, modest vertical shear and poor midlevel lapse rates preclude severe probabilities at this time. ..Leitman.. 07/23/2024 Read more