Severe Storms

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1018 AM CST Tue Dec 26 2023 Valid 261630Z - 271200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not forecast through tonight across the contiguous United States. ...Synopsis... A large, mature mid-latitude cyclone is centered over the eastern NE/KS border vicinity. This cyclone is expected to move gradually into MO, while becoming increasingly vertically stacked with time. Cold and dry air mass associated with this cyclone will dominant the sensible weather across much of the CONUS. The only exception is from the coastal Southeast through the Mid-Atlantic States. Here, an extensive warm conveyor, originating over central Mexico and the western Gulf of Mexico and splitting over the Mid-Atlantic, will contribute to broad isentropic ascent. Strongest ascent is ongoing over the SC vicinity, where enhanced low-level southeasterly flow is augmenting the modest ascent within the warm conveyor. This low-level flow is forecast to continue throughout the period while gradually shifting northward, resulting in prolonged isentropic ascent and a continued threat for isolated thunderstorms embedded within the broader precipitation shield. Highest thunderstorm coverage is expected over the western Carolinas. Some favorable low-level shear may exist across the central/eastern Carolinas, but this shear should be displaced west of any surface-based buoyancy, limiting the severe potential. ..Mosier/Thornton.. 12/26/2023 Read more

MD 2349 CONCERNING FREEZING RAIN FOR MUCH OF EASTERN NORTH DAKOTA...NORTH-CENTRAL SOUTH DAKOTA
Mesoscale Discussion 2349 NWS Storm Prediction Center Norman OK 0527 AM CST Tue Dec 26 2023 Areas affected...much of eastern North Dakota...north-central South Dakota Concerning...Freezing rain Valid 261127Z - 261630Z SUMMARY...Freezing rain, mixed occasionally with sleet, should continue across much of the discussion area through mid morning. Ice accumulations may exceed 0.05 inches/3 hours. DISCUSSION...An area of freezing rain, mixed at times with sleet, continues across the discussion area as of 1120z. The precipitation is supported by ample warm/moist advection and large-scale ascent associated with lobes of vorticity rotating around the expansive central Plains cyclone. Latest short-term deterministic and ensemble guidance reflects high probabilities of freezing rain continuing as the dominant precip type through mid morning. This is supported by RAP-based forecast soundings generally showing a warm nose between 900 and 800 mb where surface wet bulb temperatures are below freezing. Continued low- and mid-level moisture transport should result in freezing rain accumulations in excess of 0.05 inches/3 hours in many areas through 15z. ..Bunting.. 12/26/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...FGF...ABR...BIS... LAT...LON 46249768 44709964 45240064 46470041 47549918 47729865 47969766 47839695 47299692 46249768 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1018 AM CST Tue Dec 26 2023 Valid 271200Z - 281200Z ...NO CRITICAL AREAS... The forecast remains on track. For details, see the previous discussion below. ..Weinman.. 12/26/2023 .PREV DISCUSSION... /ISSUED 0145 AM CST Tue Dec 26 2023/ ...Synopsis... On Wednesday, a closed upper low will drift slowly east across the Midwest. By this time, the surface low will weaken enough that stronger winds mostly should subside. Fuels should remain moist across most of the CONUS on Wednesday with cool conditions across most of the western/central CONUS and mild, but moist conditions along the East Coast. Therefore, fire weather concerns will remain minimal. ...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 1018 AM CST Tue Dec 26 2023 Valid 271200Z - 281200Z ...NO CRITICAL AREAS... The forecast remains on track. For details, see the previous discussion below. ..Weinman.. 12/26/2023 .PREV DISCUSSION... /ISSUED 0145 AM CST Tue Dec 26 2023/ ...Synopsis... On Wednesday, a closed upper low will drift slowly east across the Midwest. By this time, the surface low will weaken enough that stronger winds mostly should subside. Fuels should remain moist across most of the CONUS on Wednesday with cool conditions across most of the western/central CONUS and mild, but moist conditions along the East Coast. Therefore, fire weather concerns will remain minimal. ...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 1018 AM CST Tue Dec 26 2023 Valid 271200Z - 281200Z ...NO CRITICAL AREAS... The forecast remains on track. For details, see the previous discussion below. ..Weinman.. 12/26/2023 .PREV DISCUSSION... /ISSUED 0145 AM CST Tue Dec 26 2023/ ...Synopsis... On Wednesday, a closed upper low will drift slowly east across the Midwest. By this time, the surface low will weaken enough that stronger winds mostly should subside. Fuels should remain moist across most of the CONUS on Wednesday with cool conditions across most of the western/central CONUS and mild, but moist conditions along the East Coast. Therefore, fire weather concerns will remain minimal. ...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 1018 AM CST Tue Dec 26 2023 Valid 271200Z - 281200Z ...NO CRITICAL AREAS... The forecast remains on track. For details, see the previous discussion below. ..Weinman.. 12/26/2023 .PREV DISCUSSION... /ISSUED 0145 AM CST Tue Dec 26 2023/ ...Synopsis... On Wednesday, a closed upper low will drift slowly east across the Midwest. By this time, the surface low will weaken enough that stronger winds mostly should subside. Fuels should remain moist across most of the CONUS on Wednesday with cool conditions across most of the western/central CONUS and mild, but moist conditions along the East Coast. Therefore, fire weather concerns will remain minimal. ...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 1018 AM CST Tue Dec 26 2023 Valid 271200Z - 281200Z ...NO CRITICAL AREAS... The forecast remains on track. For details, see the previous discussion below. ..Weinman.. 12/26/2023 .PREV DISCUSSION... /ISSUED 0145 AM CST Tue Dec 26 2023/ ...Synopsis... On Wednesday, a closed upper low will drift slowly east across the Midwest. By this time, the surface low will weaken enough that stronger winds mostly should subside. Fuels should remain moist across most of the CONUS on Wednesday with cool conditions across most of the western/central CONUS and mild, but moist conditions along the East Coast. Therefore, fire weather concerns will remain minimal. ...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 1018 AM CST Tue Dec 26 2023 Valid 271200Z - 281200Z ...NO CRITICAL AREAS... The forecast remains on track. For details, see the previous discussion below. ..Weinman.. 12/26/2023 .PREV DISCUSSION... /ISSUED 0145 AM CST Tue Dec 26 2023/ ...Synopsis... On Wednesday, a closed upper low will drift slowly east across the Midwest. By this time, the surface low will weaken enough that stronger winds mostly should subside. Fuels should remain moist across most of the CONUS on Wednesday with cool conditions across most of the western/central CONUS and mild, but moist conditions along the East Coast. Therefore, fire weather concerns will remain minimal. ...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

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