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SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1017 AM CST Tue Dec 26 2023 Valid 261700Z - 271200Z ...NO CRITICAL AREAS... Morning water vapor loops indicate a well-defined dry conveyor belt overspreading the southern High Plains, which is associated with an expansive midlevel cyclone over the central CONUS. Strong west-northwesterly flow aloft associated with this feature, coupled with a modest pressure gradient, will favor 20-25 mph sustained west-northwesterly surface winds (with gusts upwards of 35 mph) from southeast NM into the TX Trans-Pecos. Here, downslope warming/drying and boundary-layer mixing into the deep layer of dry air will contribute to 10-15 percent minimum RH this afternoon. While the area did receive some precipitation this past weekend, freeze-cured grasses may still support locally elevated fire-weather conditions given a day or two of drying and the dry/breezy conditions. ..Weinman.. 12/26/2023 .PREV DISCUSSION... /ISSUED 0142 AM CST Tue Dec 26 2023/ ...Synopsis... Some breezy conditions are possible today across the central/northern Plains as the surface pressure gradient slowly relaxes. However, cool conditions dominate across most of the CONUS. In addition, most of the CONUS has seen wetting rain within the last few days. Therefore, fire weather concerns are minimal today. ...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 1017 AM CST Tue Dec 26 2023 Valid 261700Z - 271200Z ...NO CRITICAL AREAS... Morning water vapor loops indicate a well-defined dry conveyor belt overspreading the southern High Plains, which is associated with an expansive midlevel cyclone over the central CONUS. Strong west-northwesterly flow aloft associated with this feature, coupled with a modest pressure gradient, will favor 20-25 mph sustained west-northwesterly surface winds (with gusts upwards of 35 mph) from southeast NM into the TX Trans-Pecos. Here, downslope warming/drying and boundary-layer mixing into the deep layer of dry air will contribute to 10-15 percent minimum RH this afternoon. While the area did receive some precipitation this past weekend, freeze-cured grasses may still support locally elevated fire-weather conditions given a day or two of drying and the dry/breezy conditions. ..Weinman.. 12/26/2023 .PREV DISCUSSION... /ISSUED 0142 AM CST Tue Dec 26 2023/ ...Synopsis... Some breezy conditions are possible today across the central/northern Plains as the surface pressure gradient slowly relaxes. However, cool conditions dominate across most of the CONUS. In addition, most of the CONUS has seen wetting rain within the last few days. Therefore, fire weather concerns are minimal today. ...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 1017 AM CST Tue Dec 26 2023 Valid 261700Z - 271200Z ...NO CRITICAL AREAS... Morning water vapor loops indicate a well-defined dry conveyor belt overspreading the southern High Plains, which is associated with an expansive midlevel cyclone over the central CONUS. Strong west-northwesterly flow aloft associated with this feature, coupled with a modest pressure gradient, will favor 20-25 mph sustained west-northwesterly surface winds (with gusts upwards of 35 mph) from southeast NM into the TX Trans-Pecos. Here, downslope warming/drying and boundary-layer mixing into the deep layer of dry air will contribute to 10-15 percent minimum RH this afternoon. While the area did receive some precipitation this past weekend, freeze-cured grasses may still support locally elevated fire-weather conditions given a day or two of drying and the dry/breezy conditions. ..Weinman.. 12/26/2023 .PREV DISCUSSION... /ISSUED 0142 AM CST Tue Dec 26 2023/ ...Synopsis... Some breezy conditions are possible today across the central/northern Plains as the surface pressure gradient slowly relaxes. However, cool conditions dominate across most of the CONUS. In addition, most of the CONUS has seen wetting rain within the last few days. Therefore, fire weather concerns are minimal today. ...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 1017 AM CST Tue Dec 26 2023 Valid 261700Z - 271200Z ...NO CRITICAL AREAS... Morning water vapor loops indicate a well-defined dry conveyor belt overspreading the southern High Plains, which is associated with an expansive midlevel cyclone over the central CONUS. Strong west-northwesterly flow aloft associated with this feature, coupled with a modest pressure gradient, will favor 20-25 mph sustained west-northwesterly surface winds (with gusts upwards of 35 mph) from southeast NM into the TX Trans-Pecos. Here, downslope warming/drying and boundary-layer mixing into the deep layer of dry air will contribute to 10-15 percent minimum RH this afternoon. While the area did receive some precipitation this past weekend, freeze-cured grasses may still support locally elevated fire-weather conditions given a day or two of drying and the dry/breezy conditions. ..Weinman.. 12/26/2023 .PREV DISCUSSION... /ISSUED 0142 AM CST Tue Dec 26 2023/ ...Synopsis... Some breezy conditions are possible today across the central/northern Plains as the surface pressure gradient slowly relaxes. However, cool conditions dominate across most of the CONUS. In addition, most of the CONUS has seen wetting rain within the last few days. Therefore, fire weather concerns are minimal today. ...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 1017 AM CST Tue Dec 26 2023 Valid 261700Z - 271200Z ...NO CRITICAL AREAS... Morning water vapor loops indicate a well-defined dry conveyor belt overspreading the southern High Plains, which is associated with an expansive midlevel cyclone over the central CONUS. Strong west-northwesterly flow aloft associated with this feature, coupled with a modest pressure gradient, will favor 20-25 mph sustained west-northwesterly surface winds (with gusts upwards of 35 mph) from southeast NM into the TX Trans-Pecos. Here, downslope warming/drying and boundary-layer mixing into the deep layer of dry air will contribute to 10-15 percent minimum RH this afternoon. While the area did receive some precipitation this past weekend, freeze-cured grasses may still support locally elevated fire-weather conditions given a day or two of drying and the dry/breezy conditions. ..Weinman.. 12/26/2023 .PREV DISCUSSION... /ISSUED 0142 AM CST Tue Dec 26 2023/ ...Synopsis... Some breezy conditions are possible today across the central/northern Plains as the surface pressure gradient slowly relaxes. However, cool conditions dominate across most of the CONUS. In addition, most of the CONUS has seen wetting rain within the last few days. Therefore, fire weather concerns are minimal today. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

MD 2348 CONCERNING HEAVY SNOW FOR WESTERN SOUTH DAKOTA...EASTERN WYOMING...NORTHEAST COLORADO...WESTERN NEBRASKA PANHANDLE...NORTHWEST KANSAS
Mesoscale Discussion 2348 NWS Storm Prediction Center Norman OK 0433 AM CST Tue Dec 26 2023 Areas affected...Western South Dakota...eastern Wyoming...northeast Colorado...western Nebraska Panhandle...northwest Kansas Concerning...Heavy snow Valid 261033Z - 261600Z SUMMARY...Heavy snow, with rates in excess of one inch/hour, will continue across much of the discussion area through mid morning. In addition, strong surface winds with frequent gusts between 40 and 50 kts, will result in blizzard conditions in some areas. DISCUSSION...Regional radar composite imagery depicts a rather large area of moderate to heavy snow extending from western SD southward over eastern WY/western NE Panhandle and into parts of northeast CO/northwest KS at 1025z. This precipitation is associated with a pronounced zone of 850 mb warm air advection, on the western periphery of a pronounced dry slot associated with the occluded cyclone over the central Plains. An impressive flow of moisture with the warm conveyor belt will continue to feed into the western portion of the cyclone (across the discussion area), and combine with lobes of vorticity rotating around the upper low to produce lift for areas of moderate/heavy snow to continue through at least mid morning. Snowfall rates of one inch/hour will remain possible. Although the surface low should continue to weaken with time, the surface pressure gradient across this area will support frequent wind gusts of 40 to 50 kts through mid morning, resulting in areas of near-blizzard/blizzard conditions. ..Bunting.. 12/26/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LBF...UNR...GLD...BOU...CYS... LAT...LON 41990548 44920408 45230354 45280185 44780133 43660140 41790333 40680317 40070220 39620153 39360107 38760105 38590165 38910269 39510392 40010452 41310560 41990548 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0624 AM CST Tue Dec 26 2023 Valid 261300Z - 271200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast through tonight across the contiguous United States. ...Synopsis/Discussion... A slowly progressive pattern will persist in mid/upper levels, dominated over the CONUS by a large synoptic cyclone now centered over the eastern KS/NE border region. Through 12Z tomorrow, the 500-mb low is forecast to loop cycloidally along a net eastward track to northern MO, while a series of shortwave troughs and vorticity maxima orbit the gyre. The already-occluded surface low -- analyzed at 11Z just east of HSI, will become increasingly stacked under the mid/upper center. The related occluded/cold front was analyzed from the low across southeastern SD, southern MN, southern Lake Michigan, central/eastern IN, eastern parts of KY/TN, western GA, and the eastern Gulf. Gradual frontolysis is expected with this boundary as it moves slowly eastward toward the southern Atlantic Coast and Tidewater region. The southern part will cross FL today, moving offshore from FL by the 00-03Z time frame. A broad, prefrontal conveyor of low-level warm advection and moisture transport will continue. Through tonight, the bulk of thunderstorm coverage, and the strongest activity, should be over Atlantic waters, where sea-air fluxes will support greatest inflow- layer theta-e. However, weak buoyancy may deepen enough to support sporadic lightning in convective clusters within the broader precip shield over land. Lack of greater low-level instability and shear should preclude an organized severe threat. ..Edwards.. 12/26/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0624 AM CST Tue Dec 26 2023 Valid 261300Z - 271200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast through tonight across the contiguous United States. ...Synopsis/Discussion... A slowly progressive pattern will persist in mid/upper levels, dominated over the CONUS by a large synoptic cyclone now centered over the eastern KS/NE border region. Through 12Z tomorrow, the 500-mb low is forecast to loop cycloidally along a net eastward track to northern MO, while a series of shortwave troughs and vorticity maxima orbit the gyre. The already-occluded surface low -- analyzed at 11Z just east of HSI, will become increasingly stacked under the mid/upper center. The related occluded/cold front was analyzed from the low across southeastern SD, southern MN, southern Lake Michigan, central/eastern IN, eastern parts of KY/TN, western GA, and the eastern Gulf. Gradual frontolysis is expected with this boundary as it moves slowly eastward toward the southern Atlantic Coast and Tidewater region. The southern part will cross FL today, moving offshore from FL by the 00-03Z time frame. A broad, prefrontal conveyor of low-level warm advection and moisture transport will continue. Through tonight, the bulk of thunderstorm coverage, and the strongest activity, should be over Atlantic waters, where sea-air fluxes will support greatest inflow- layer theta-e. However, weak buoyancy may deepen enough to support sporadic lightning in convective clusters within the broader precip shield over land. Lack of greater low-level instability and shear should preclude an organized severe threat. ..Edwards.. 12/26/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0624 AM CST Tue Dec 26 2023 Valid 261300Z - 271200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast through tonight across the contiguous United States. ...Synopsis/Discussion... A slowly progressive pattern will persist in mid/upper levels, dominated over the CONUS by a large synoptic cyclone now centered over the eastern KS/NE border region. Through 12Z tomorrow, the 500-mb low is forecast to loop cycloidally along a net eastward track to northern MO, while a series of shortwave troughs and vorticity maxima orbit the gyre. The already-occluded surface low -- analyzed at 11Z just east of HSI, will become increasingly stacked under the mid/upper center. The related occluded/cold front was analyzed from the low across southeastern SD, southern MN, southern Lake Michigan, central/eastern IN, eastern parts of KY/TN, western GA, and the eastern Gulf. Gradual frontolysis is expected with this boundary as it moves slowly eastward toward the southern Atlantic Coast and Tidewater region. The southern part will cross FL today, moving offshore from FL by the 00-03Z time frame. A broad, prefrontal conveyor of low-level warm advection and moisture transport will continue. Through tonight, the bulk of thunderstorm coverage, and the strongest activity, should be over Atlantic waters, where sea-air fluxes will support greatest inflow- layer theta-e. However, weak buoyancy may deepen enough to support sporadic lightning in convective clusters within the broader precip shield over land. Lack of greater low-level instability and shear should preclude an organized severe threat. ..Edwards.. 12/26/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0624 AM CST Tue Dec 26 2023 Valid 261300Z - 271200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast through tonight across the contiguous United States. ...Synopsis/Discussion... A slowly progressive pattern will persist in mid/upper levels, dominated over the CONUS by a large synoptic cyclone now centered over the eastern KS/NE border region. Through 12Z tomorrow, the 500-mb low is forecast to loop cycloidally along a net eastward track to northern MO, while a series of shortwave troughs and vorticity maxima orbit the gyre. The already-occluded surface low -- analyzed at 11Z just east of HSI, will become increasingly stacked under the mid/upper center. The related occluded/cold front was analyzed from the low across southeastern SD, southern MN, southern Lake Michigan, central/eastern IN, eastern parts of KY/TN, western GA, and the eastern Gulf. Gradual frontolysis is expected with this boundary as it moves slowly eastward toward the southern Atlantic Coast and Tidewater region. The southern part will cross FL today, moving offshore from FL by the 00-03Z time frame. A broad, prefrontal conveyor of low-level warm advection and moisture transport will continue. Through tonight, the bulk of thunderstorm coverage, and the strongest activity, should be over Atlantic waters, where sea-air fluxes will support greatest inflow- layer theta-e. However, weak buoyancy may deepen enough to support sporadic lightning in convective clusters within the broader precip shield over land. Lack of greater low-level instability and shear should preclude an organized severe threat. ..Edwards.. 12/26/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0624 AM CST Tue Dec 26 2023 Valid 261300Z - 271200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast through tonight across the contiguous United States. ...Synopsis/Discussion... A slowly progressive pattern will persist in mid/upper levels, dominated over the CONUS by a large synoptic cyclone now centered over the eastern KS/NE border region. Through 12Z tomorrow, the 500-mb low is forecast to loop cycloidally along a net eastward track to northern MO, while a series of shortwave troughs and vorticity maxima orbit the gyre. The already-occluded surface low -- analyzed at 11Z just east of HSI, will become increasingly stacked under the mid/upper center. The related occluded/cold front was analyzed from the low across southeastern SD, southern MN, southern Lake Michigan, central/eastern IN, eastern parts of KY/TN, western GA, and the eastern Gulf. Gradual frontolysis is expected with this boundary as it moves slowly eastward toward the southern Atlantic Coast and Tidewater region. The southern part will cross FL today, moving offshore from FL by the 00-03Z time frame. A broad, prefrontal conveyor of low-level warm advection and moisture transport will continue. Through tonight, the bulk of thunderstorm coverage, and the strongest activity, should be over Atlantic waters, where sea-air fluxes will support greatest inflow- layer theta-e. However, weak buoyancy may deepen enough to support sporadic lightning in convective clusters within the broader precip shield over land. Lack of greater low-level instability and shear should preclude an organized severe threat. ..Edwards.. 12/26/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0624 AM CST Tue Dec 26 2023 Valid 261300Z - 271200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast through tonight across the contiguous United States. ...Synopsis/Discussion... A slowly progressive pattern will persist in mid/upper levels, dominated over the CONUS by a large synoptic cyclone now centered over the eastern KS/NE border region. Through 12Z tomorrow, the 500-mb low is forecast to loop cycloidally along a net eastward track to northern MO, while a series of shortwave troughs and vorticity maxima orbit the gyre. The already-occluded surface low -- analyzed at 11Z just east of HSI, will become increasingly stacked under the mid/upper center. The related occluded/cold front was analyzed from the low across southeastern SD, southern MN, southern Lake Michigan, central/eastern IN, eastern parts of KY/TN, western GA, and the eastern Gulf. Gradual frontolysis is expected with this boundary as it moves slowly eastward toward the southern Atlantic Coast and Tidewater region. The southern part will cross FL today, moving offshore from FL by the 00-03Z time frame. A broad, prefrontal conveyor of low-level warm advection and moisture transport will continue. Through tonight, the bulk of thunderstorm coverage, and the strongest activity, should be over Atlantic waters, where sea-air fluxes will support greatest inflow- layer theta-e. However, weak buoyancy may deepen enough to support sporadic lightning in convective clusters within the broader precip shield over land. Lack of greater low-level instability and shear should preclude an organized severe threat. ..Edwards.. 12/26/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0624 AM CST Tue Dec 26 2023 Valid 261300Z - 271200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast through tonight across the contiguous United States. ...Synopsis/Discussion... A slowly progressive pattern will persist in mid/upper levels, dominated over the CONUS by a large synoptic cyclone now centered over the eastern KS/NE border region. Through 12Z tomorrow, the 500-mb low is forecast to loop cycloidally along a net eastward track to northern MO, while a series of shortwave troughs and vorticity maxima orbit the gyre. The already-occluded surface low -- analyzed at 11Z just east of HSI, will become increasingly stacked under the mid/upper center. The related occluded/cold front was analyzed from the low across southeastern SD, southern MN, southern Lake Michigan, central/eastern IN, eastern parts of KY/TN, western GA, and the eastern Gulf. Gradual frontolysis is expected with this boundary as it moves slowly eastward toward the southern Atlantic Coast and Tidewater region. The southern part will cross FL today, moving offshore from FL by the 00-03Z time frame. A broad, prefrontal conveyor of low-level warm advection and moisture transport will continue. Through tonight, the bulk of thunderstorm coverage, and the strongest activity, should be over Atlantic waters, where sea-air fluxes will support greatest inflow- layer theta-e. However, weak buoyancy may deepen enough to support sporadic lightning in convective clusters within the broader precip shield over land. Lack of greater low-level instability and shear should preclude an organized severe threat. ..Edwards.. 12/26/2023 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0624 AM CST Tue Dec 26 2023 Valid 261300Z - 271200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast through tonight across the contiguous United States. ...Synopsis/Discussion... A slowly progressive pattern will persist in mid/upper levels, dominated over the CONUS by a large synoptic cyclone now centered over the eastern KS/NE border region. Through 12Z tomorrow, the 500-mb low is forecast to loop cycloidally along a net eastward track to northern MO, while a series of shortwave troughs and vorticity maxima orbit the gyre. The already-occluded surface low -- analyzed at 11Z just east of HSI, will become increasingly stacked under the mid/upper center. The related occluded/cold front was analyzed from the low across southeastern SD, southern MN, southern Lake Michigan, central/eastern IN, eastern parts of KY/TN, western GA, and the eastern Gulf. Gradual frontolysis is expected with this boundary as it moves slowly eastward toward the southern Atlantic Coast and Tidewater region. The southern part will cross FL today, moving offshore from FL by the 00-03Z time frame. A broad, prefrontal conveyor of low-level warm advection and moisture transport will continue. Through tonight, the bulk of thunderstorm coverage, and the strongest activity, should be over Atlantic waters, where sea-air fluxes will support greatest inflow- layer theta-e. However, weak buoyancy may deepen enough to support sporadic lightning in convective clusters within the broader precip shield over land. Lack of greater low-level instability and shear should preclude an organized severe threat. ..Edwards.. 12/26/2023 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0258 AM CST Tue Dec 26 2023 Valid 291200Z - 031200Z ...DISCUSSION... A series of reinforcing upper shortwave troughs will maintain mean troughing over the eastern U.S. during the Day 4-8 period. Upper ridging across the western states will persist on Day 4/Fri before an upper trough moves inland along the Pacific coast. This system will shift east toward the southern High Plains on Day 6/Sun while merging with the mean upper trough across the east late in the forecast period. Prior cold frontal passages deep into the Gulf of Mexico, and surface high pressure over the Plains, will preclude thunderstorm activity across most of the CONUS. However, by the end of the period, some modest moisture return may impinge on the western/central Gulf coast as the ejecting upper shortwave trough over the southern High Plains merges with the eastern trough over the Lower MS Valley/Southeast. However, quality moisture return appears unlikely, and severe thunderstorm potential will remain low. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0258 AM CST Tue Dec 26 2023 Valid 291200Z - 031200Z ...DISCUSSION... A series of reinforcing upper shortwave troughs will maintain mean troughing over the eastern U.S. during the Day 4-8 period. Upper ridging across the western states will persist on Day 4/Fri before an upper trough moves inland along the Pacific coast. This system will shift east toward the southern High Plains on Day 6/Sun while merging with the mean upper trough across the east late in the forecast period. Prior cold frontal passages deep into the Gulf of Mexico, and surface high pressure over the Plains, will preclude thunderstorm activity across most of the CONUS. However, by the end of the period, some modest moisture return may impinge on the western/central Gulf coast as the ejecting upper shortwave trough over the southern High Plains merges with the eastern trough over the Lower MS Valley/Southeast. However, quality moisture return appears unlikely, and severe thunderstorm potential will remain low. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0258 AM CST Tue Dec 26 2023 Valid 291200Z - 031200Z ...DISCUSSION... A series of reinforcing upper shortwave troughs will maintain mean troughing over the eastern U.S. during the Day 4-8 period. Upper ridging across the western states will persist on Day 4/Fri before an upper trough moves inland along the Pacific coast. This system will shift east toward the southern High Plains on Day 6/Sun while merging with the mean upper trough across the east late in the forecast period. Prior cold frontal passages deep into the Gulf of Mexico, and surface high pressure over the Plains, will preclude thunderstorm activity across most of the CONUS. However, by the end of the period, some modest moisture return may impinge on the western/central Gulf coast as the ejecting upper shortwave trough over the southern High Plains merges with the eastern trough over the Lower MS Valley/Southeast. However, quality moisture return appears unlikely, and severe thunderstorm potential will remain low. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0258 AM CST Tue Dec 26 2023 Valid 291200Z - 031200Z ...DISCUSSION... A series of reinforcing upper shortwave troughs will maintain mean troughing over the eastern U.S. during the Day 4-8 period. Upper ridging across the western states will persist on Day 4/Fri before an upper trough moves inland along the Pacific coast. This system will shift east toward the southern High Plains on Day 6/Sun while merging with the mean upper trough across the east late in the forecast period. Prior cold frontal passages deep into the Gulf of Mexico, and surface high pressure over the Plains, will preclude thunderstorm activity across most of the CONUS. However, by the end of the period, some modest moisture return may impinge on the western/central Gulf coast as the ejecting upper shortwave trough over the southern High Plains merges with the eastern trough over the Lower MS Valley/Southeast. However, quality moisture return appears unlikely, and severe thunderstorm potential will remain low. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0258 AM CST Tue Dec 26 2023 Valid 291200Z - 031200Z ...DISCUSSION... A series of reinforcing upper shortwave troughs will maintain mean troughing over the eastern U.S. during the Day 4-8 period. Upper ridging across the western states will persist on Day 4/Fri before an upper trough moves inland along the Pacific coast. This system will shift east toward the southern High Plains on Day 6/Sun while merging with the mean upper trough across the east late in the forecast period. Prior cold frontal passages deep into the Gulf of Mexico, and surface high pressure over the Plains, will preclude thunderstorm activity across most of the CONUS. However, by the end of the period, some modest moisture return may impinge on the western/central Gulf coast as the ejecting upper shortwave trough over the southern High Plains merges with the eastern trough over the Lower MS Valley/Southeast. However, quality moisture return appears unlikely, and severe thunderstorm potential will remain low. Read more