Severe Storms

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0148 PM CST Fri Dec 22 2023 Valid 222000Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SOUTHERN ARIZONA AND INTERIOR SOUTHERN CALIFORNIA... ...SUMMARY... Isolated hail and gusty winds remain possible this afternoon and evening across parts of southern Arizona and vicinity. ...20Z Update... No changes have been made to the Marginal Risk. The potential for isolated hail and gusty winds continues with any robust convection that can move from northwest Mexico into southern AZ this afternoon and evening. ..Gleason.. 12/22/2023 .PREV DISCUSSION... /ISSUED 1022 AM CST Fri Dec 22 2023/ ...Southwest US... Morning water vapor loop shows a compact upper-low off the coast to the southwest of San Diego, CA. A 70+ knot mid-level jet max is rotating around the base of the low, and will overspread northwest Mexico and into southern AZ tonight. Widespread clouds and scattered precipitation will limit heating/destabilization in most parts of AZ today. However, visible imagery shows broken cloud cover over southern CA just ahead of the upper low. Steep mid-level lapse rates and cold temperatures aloft may result in sufficient CAPE for a few robust updrafts this afternoon. CAM guidance suggests the main area of concern is along and east of the Colorado River valley. A few storms may produce hail and gusty wind in this region this afternoon. Other strong storms may form in the low-level warm-advection zone and beneath the strong winds aloft across southeast AZ after dark. This area will see very little daytime heating or destabilization, but stronger vertical shear profiles and sufficient CAPE could encourage an organized storm or two capable of gusty winds. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0148 PM CST Fri Dec 22 2023 Valid 222000Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SOUTHERN ARIZONA AND INTERIOR SOUTHERN CALIFORNIA... ...SUMMARY... Isolated hail and gusty winds remain possible this afternoon and evening across parts of southern Arizona and vicinity. ...20Z Update... No changes have been made to the Marginal Risk. The potential for isolated hail and gusty winds continues with any robust convection that can move from northwest Mexico into southern AZ this afternoon and evening. ..Gleason.. 12/22/2023 .PREV DISCUSSION... /ISSUED 1022 AM CST Fri Dec 22 2023/ ...Southwest US... Morning water vapor loop shows a compact upper-low off the coast to the southwest of San Diego, CA. A 70+ knot mid-level jet max is rotating around the base of the low, and will overspread northwest Mexico and into southern AZ tonight. Widespread clouds and scattered precipitation will limit heating/destabilization in most parts of AZ today. However, visible imagery shows broken cloud cover over southern CA just ahead of the upper low. Steep mid-level lapse rates and cold temperatures aloft may result in sufficient CAPE for a few robust updrafts this afternoon. CAM guidance suggests the main area of concern is along and east of the Colorado River valley. A few storms may produce hail and gusty wind in this region this afternoon. Other strong storms may form in the low-level warm-advection zone and beneath the strong winds aloft across southeast AZ after dark. This area will see very little daytime heating or destabilization, but stronger vertical shear profiles and sufficient CAPE could encourage an organized storm or two capable of gusty winds. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0148 PM CST Fri Dec 22 2023 Valid 222000Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SOUTHERN ARIZONA AND INTERIOR SOUTHERN CALIFORNIA... ...SUMMARY... Isolated hail and gusty winds remain possible this afternoon and evening across parts of southern Arizona and vicinity. ...20Z Update... No changes have been made to the Marginal Risk. The potential for isolated hail and gusty winds continues with any robust convection that can move from northwest Mexico into southern AZ this afternoon and evening. ..Gleason.. 12/22/2023 .PREV DISCUSSION... /ISSUED 1022 AM CST Fri Dec 22 2023/ ...Southwest US... Morning water vapor loop shows a compact upper-low off the coast to the southwest of San Diego, CA. A 70+ knot mid-level jet max is rotating around the base of the low, and will overspread northwest Mexico and into southern AZ tonight. Widespread clouds and scattered precipitation will limit heating/destabilization in most parts of AZ today. However, visible imagery shows broken cloud cover over southern CA just ahead of the upper low. Steep mid-level lapse rates and cold temperatures aloft may result in sufficient CAPE for a few robust updrafts this afternoon. CAM guidance suggests the main area of concern is along and east of the Colorado River valley. A few storms may produce hail and gusty wind in this region this afternoon. Other strong storms may form in the low-level warm-advection zone and beneath the strong winds aloft across southeast AZ after dark. This area will see very little daytime heating or destabilization, but stronger vertical shear profiles and sufficient CAPE could encourage an organized storm or two capable of gusty winds. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0103 PM CST Fri Dec 22 2023 Valid 231200Z - 241200Z ...NO CRITICAL AREAS... The forecast remains on track. For details, see the previous discussion below. ..Weinman.. 12/22/2023 .PREV DISCUSSION... /ISSUED 1157 PM CST Thu Dec 21 2023/ ...Synopsis... Some breezy conditions are likely on Saturday across the central Plains and Southwest as a lee cyclone develops. However, significant moisture will also accompany this cyclone with widespread wetting rain expected. Elsewhere, fuels remain moist with cool and/or moist conditions. Therefore, fire-weather conditions remain minimal across the CONUS. ...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 0103 PM CST Fri Dec 22 2023 Valid 231200Z - 241200Z ...NO CRITICAL AREAS... The forecast remains on track. For details, see the previous discussion below. ..Weinman.. 12/22/2023 .PREV DISCUSSION... /ISSUED 1157 PM CST Thu Dec 21 2023/ ...Synopsis... Some breezy conditions are likely on Saturday across the central Plains and Southwest as a lee cyclone develops. However, significant moisture will also accompany this cyclone with widespread wetting rain expected. Elsewhere, fuels remain moist with cool and/or moist conditions. Therefore, fire-weather conditions remain minimal across the CONUS. ...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 0103 PM CST Fri Dec 22 2023 Valid 231200Z - 241200Z ...NO CRITICAL AREAS... The forecast remains on track. For details, see the previous discussion below. ..Weinman.. 12/22/2023 .PREV DISCUSSION... /ISSUED 1157 PM CST Thu Dec 21 2023/ ...Synopsis... Some breezy conditions are likely on Saturday across the central Plains and Southwest as a lee cyclone develops. However, significant moisture will also accompany this cyclone with widespread wetting rain expected. Elsewhere, fuels remain moist with cool and/or moist conditions. Therefore, fire-weather conditions remain minimal across the CONUS. ...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 0103 PM CST Fri Dec 22 2023 Valid 231200Z - 241200Z ...NO CRITICAL AREAS... The forecast remains on track. For details, see the previous discussion below. ..Weinman.. 12/22/2023 .PREV DISCUSSION... /ISSUED 1157 PM CST Thu Dec 21 2023/ ...Synopsis... Some breezy conditions are likely on Saturday across the central Plains and Southwest as a lee cyclone develops. However, significant moisture will also accompany this cyclone with widespread wetting rain expected. Elsewhere, fuels remain moist with cool and/or moist conditions. Therefore, fire-weather conditions remain minimal across the CONUS. ...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 0103 PM CST Fri Dec 22 2023 Valid 231200Z - 241200Z ...NO CRITICAL AREAS... The forecast remains on track. For details, see the previous discussion below. ..Weinman.. 12/22/2023 .PREV DISCUSSION... /ISSUED 1157 PM CST Thu Dec 21 2023/ ...Synopsis... Some breezy conditions are likely on Saturday across the central Plains and Southwest as a lee cyclone develops. However, significant moisture will also accompany this cyclone with widespread wetting rain expected. Elsewhere, fuels remain moist with cool and/or moist conditions. Therefore, fire-weather conditions remain minimal across the CONUS. ...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 0103 PM CST Fri Dec 22 2023 Valid 231200Z - 241200Z ...NO CRITICAL AREAS... The forecast remains on track. For details, see the previous discussion below. ..Weinman.. 12/22/2023 .PREV DISCUSSION... /ISSUED 1157 PM CST Thu Dec 21 2023/ ...Synopsis... Some breezy conditions are likely on Saturday across the central Plains and Southwest as a lee cyclone develops. However, significant moisture will also accompany this cyclone with widespread wetting rain expected. Elsewhere, fuels remain moist with cool and/or moist conditions. Therefore, fire-weather conditions remain minimal across the CONUS. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1124 AM CST Fri Dec 22 2023 Valid 231200Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTHERN HIGH PLAINS... ...SUMMARY... Isolated severe thunderstorms capable of producing hail and strong/gusty winds appear possible across parts of the southern High Plains, mainly Saturday afternoon and evening. ...Southern High Plains... Large-scale upper troughing will encompass much of the western states on Saturday. A southern-stream shortwave trough is expected to move eastward from the Southwest across the southern/central High Plans through the period. Large-scale ascent preceding this shortwave trough will encourage the development of a lee surface low across eastern CO through the day, with the low then ejecting eastward across KS Saturday night through early Sunday morning. Low-level moisture will continue to stream northward ahead of the surface low and a Pacific cold front advancing eastward across the southern High Plains. Widespread cloudiness and limited daytime heating should temper the degree of instability that can develop through Saturday afternoon across the southern High Plains. Even so, cooling mid-level temperatures and somewhat steepened lapse rates aloft ahead of the upper trough should aid in at least weak destabilization across parts of far eastern NM into west TX and the TX Panhandle by late Saturday afternoon. MLCAPE generally ranging from 500-750 J/kg should prove adequate in tandem with strong deep-layer shear of 40-50 kt to support organized updrafts. Convection that forms along or just ahead of the Pacific cold front may be initially discrete and pose a threat for isolated severe hail given the favorable shear. With time, upscale growth into one or more clusters appears probable through Saturday evening as thunderstorms spread east-northeastward across west TX and the TX Panhandle. Even though low-level lapse rates should remain modest with limited daytime heating, some threat for strong to locally severe wind gusts may still exist as this mode transition occurs. Somewhat greater low-level moisture, with surface dewpoints in the upper 50s to low 60s, should be in place farther east into OK and north/central TX. One or more thunderstorm clusters should move across these areas Saturday night into early Sunday morning. While both low-level and deep-layer shear appear favorable for organized convection, poor lapse rates, weak boundary-layer instability, and some MLCIN should tend to limit the threat for surface-based thunderstorms. Still, forecast instability trends will be closely monitored for locations east of the current Marginal Risk. ..Gleason.. 12/22/2023 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1124 AM CST Fri Dec 22 2023 Valid 231200Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTHERN HIGH PLAINS... ...SUMMARY... Isolated severe thunderstorms capable of producing hail and strong/gusty winds appear possible across parts of the southern High Plains, mainly Saturday afternoon and evening. ...Southern High Plains... Large-scale upper troughing will encompass much of the western states on Saturday. A southern-stream shortwave trough is expected to move eastward from the Southwest across the southern/central High Plans through the period. Large-scale ascent preceding this shortwave trough will encourage the development of a lee surface low across eastern CO through the day, with the low then ejecting eastward across KS Saturday night through early Sunday morning. Low-level moisture will continue to stream northward ahead of the surface low and a Pacific cold front advancing eastward across the southern High Plains. Widespread cloudiness and limited daytime heating should temper the degree of instability that can develop through Saturday afternoon across the southern High Plains. Even so, cooling mid-level temperatures and somewhat steepened lapse rates aloft ahead of the upper trough should aid in at least weak destabilization across parts of far eastern NM into west TX and the TX Panhandle by late Saturday afternoon. MLCAPE generally ranging from 500-750 J/kg should prove adequate in tandem with strong deep-layer shear of 40-50 kt to support organized updrafts. Convection that forms along or just ahead of the Pacific cold front may be initially discrete and pose a threat for isolated severe hail given the favorable shear. With time, upscale growth into one or more clusters appears probable through Saturday evening as thunderstorms spread east-northeastward across west TX and the TX Panhandle. Even though low-level lapse rates should remain modest with limited daytime heating, some threat for strong to locally severe wind gusts may still exist as this mode transition occurs. Somewhat greater low-level moisture, with surface dewpoints in the upper 50s to low 60s, should be in place farther east into OK and north/central TX. One or more thunderstorm clusters should move across these areas Saturday night into early Sunday morning. While both low-level and deep-layer shear appear favorable for organized convection, poor lapse rates, weak boundary-layer instability, and some MLCIN should tend to limit the threat for surface-based thunderstorms. Still, forecast instability trends will be closely monitored for locations east of the current Marginal Risk. ..Gleason.. 12/22/2023 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1124 AM CST Fri Dec 22 2023 Valid 231200Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTHERN HIGH PLAINS... ...SUMMARY... Isolated severe thunderstorms capable of producing hail and strong/gusty winds appear possible across parts of the southern High Plains, mainly Saturday afternoon and evening. ...Southern High Plains... Large-scale upper troughing will encompass much of the western states on Saturday. A southern-stream shortwave trough is expected to move eastward from the Southwest across the southern/central High Plans through the period. Large-scale ascent preceding this shortwave trough will encourage the development of a lee surface low across eastern CO through the day, with the low then ejecting eastward across KS Saturday night through early Sunday morning. Low-level moisture will continue to stream northward ahead of the surface low and a Pacific cold front advancing eastward across the southern High Plains. Widespread cloudiness and limited daytime heating should temper the degree of instability that can develop through Saturday afternoon across the southern High Plains. Even so, cooling mid-level temperatures and somewhat steepened lapse rates aloft ahead of the upper trough should aid in at least weak destabilization across parts of far eastern NM into west TX and the TX Panhandle by late Saturday afternoon. MLCAPE generally ranging from 500-750 J/kg should prove adequate in tandem with strong deep-layer shear of 40-50 kt to support organized updrafts. Convection that forms along or just ahead of the Pacific cold front may be initially discrete and pose a threat for isolated severe hail given the favorable shear. With time, upscale growth into one or more clusters appears probable through Saturday evening as thunderstorms spread east-northeastward across west TX and the TX Panhandle. Even though low-level lapse rates should remain modest with limited daytime heating, some threat for strong to locally severe wind gusts may still exist as this mode transition occurs. Somewhat greater low-level moisture, with surface dewpoints in the upper 50s to low 60s, should be in place farther east into OK and north/central TX. One or more thunderstorm clusters should move across these areas Saturday night into early Sunday morning. While both low-level and deep-layer shear appear favorable for organized convection, poor lapse rates, weak boundary-layer instability, and some MLCIN should tend to limit the threat for surface-based thunderstorms. Still, forecast instability trends will be closely monitored for locations east of the current Marginal Risk. ..Gleason.. 12/22/2023 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1124 AM CST Fri Dec 22 2023 Valid 231200Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTHERN HIGH PLAINS... ...SUMMARY... Isolated severe thunderstorms capable of producing hail and strong/gusty winds appear possible across parts of the southern High Plains, mainly Saturday afternoon and evening. ...Southern High Plains... Large-scale upper troughing will encompass much of the western states on Saturday. A southern-stream shortwave trough is expected to move eastward from the Southwest across the southern/central High Plans through the period. Large-scale ascent preceding this shortwave trough will encourage the development of a lee surface low across eastern CO through the day, with the low then ejecting eastward across KS Saturday night through early Sunday morning. Low-level moisture will continue to stream northward ahead of the surface low and a Pacific cold front advancing eastward across the southern High Plains. Widespread cloudiness and limited daytime heating should temper the degree of instability that can develop through Saturday afternoon across the southern High Plains. Even so, cooling mid-level temperatures and somewhat steepened lapse rates aloft ahead of the upper trough should aid in at least weak destabilization across parts of far eastern NM into west TX and the TX Panhandle by late Saturday afternoon. MLCAPE generally ranging from 500-750 J/kg should prove adequate in tandem with strong deep-layer shear of 40-50 kt to support organized updrafts. Convection that forms along or just ahead of the Pacific cold front may be initially discrete and pose a threat for isolated severe hail given the favorable shear. With time, upscale growth into one or more clusters appears probable through Saturday evening as thunderstorms spread east-northeastward across west TX and the TX Panhandle. Even though low-level lapse rates should remain modest with limited daytime heating, some threat for strong to locally severe wind gusts may still exist as this mode transition occurs. Somewhat greater low-level moisture, with surface dewpoints in the upper 50s to low 60s, should be in place farther east into OK and north/central TX. One or more thunderstorm clusters should move across these areas Saturday night into early Sunday morning. While both low-level and deep-layer shear appear favorable for organized convection, poor lapse rates, weak boundary-layer instability, and some MLCIN should tend to limit the threat for surface-based thunderstorms. Still, forecast instability trends will be closely monitored for locations east of the current Marginal Risk. ..Gleason.. 12/22/2023 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1124 AM CST Fri Dec 22 2023 Valid 231200Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTHERN HIGH PLAINS... ...SUMMARY... Isolated severe thunderstorms capable of producing hail and strong/gusty winds appear possible across parts of the southern High Plains, mainly Saturday afternoon and evening. ...Southern High Plains... Large-scale upper troughing will encompass much of the western states on Saturday. A southern-stream shortwave trough is expected to move eastward from the Southwest across the southern/central High Plans through the period. Large-scale ascent preceding this shortwave trough will encourage the development of a lee surface low across eastern CO through the day, with the low then ejecting eastward across KS Saturday night through early Sunday morning. Low-level moisture will continue to stream northward ahead of the surface low and a Pacific cold front advancing eastward across the southern High Plains. Widespread cloudiness and limited daytime heating should temper the degree of instability that can develop through Saturday afternoon across the southern High Plains. Even so, cooling mid-level temperatures and somewhat steepened lapse rates aloft ahead of the upper trough should aid in at least weak destabilization across parts of far eastern NM into west TX and the TX Panhandle by late Saturday afternoon. MLCAPE generally ranging from 500-750 J/kg should prove adequate in tandem with strong deep-layer shear of 40-50 kt to support organized updrafts. Convection that forms along or just ahead of the Pacific cold front may be initially discrete and pose a threat for isolated severe hail given the favorable shear. With time, upscale growth into one or more clusters appears probable through Saturday evening as thunderstorms spread east-northeastward across west TX and the TX Panhandle. Even though low-level lapse rates should remain modest with limited daytime heating, some threat for strong to locally severe wind gusts may still exist as this mode transition occurs. Somewhat greater low-level moisture, with surface dewpoints in the upper 50s to low 60s, should be in place farther east into OK and north/central TX. One or more thunderstorm clusters should move across these areas Saturday night into early Sunday morning. While both low-level and deep-layer shear appear favorable for organized convection, poor lapse rates, weak boundary-layer instability, and some MLCIN should tend to limit the threat for surface-based thunderstorms. Still, forecast instability trends will be closely monitored for locations east of the current Marginal Risk. ..Gleason.. 12/22/2023 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1124 AM CST Fri Dec 22 2023 Valid 231200Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTHERN HIGH PLAINS... ...SUMMARY... Isolated severe thunderstorms capable of producing hail and strong/gusty winds appear possible across parts of the southern High Plains, mainly Saturday afternoon and evening. ...Southern High Plains... Large-scale upper troughing will encompass much of the western states on Saturday. A southern-stream shortwave trough is expected to move eastward from the Southwest across the southern/central High Plans through the period. Large-scale ascent preceding this shortwave trough will encourage the development of a lee surface low across eastern CO through the day, with the low then ejecting eastward across KS Saturday night through early Sunday morning. Low-level moisture will continue to stream northward ahead of the surface low and a Pacific cold front advancing eastward across the southern High Plains. Widespread cloudiness and limited daytime heating should temper the degree of instability that can develop through Saturday afternoon across the southern High Plains. Even so, cooling mid-level temperatures and somewhat steepened lapse rates aloft ahead of the upper trough should aid in at least weak destabilization across parts of far eastern NM into west TX and the TX Panhandle by late Saturday afternoon. MLCAPE generally ranging from 500-750 J/kg should prove adequate in tandem with strong deep-layer shear of 40-50 kt to support organized updrafts. Convection that forms along or just ahead of the Pacific cold front may be initially discrete and pose a threat for isolated severe hail given the favorable shear. With time, upscale growth into one or more clusters appears probable through Saturday evening as thunderstorms spread east-northeastward across west TX and the TX Panhandle. Even though low-level lapse rates should remain modest with limited daytime heating, some threat for strong to locally severe wind gusts may still exist as this mode transition occurs. Somewhat greater low-level moisture, with surface dewpoints in the upper 50s to low 60s, should be in place farther east into OK and north/central TX. One or more thunderstorm clusters should move across these areas Saturday night into early Sunday morning. While both low-level and deep-layer shear appear favorable for organized convection, poor lapse rates, weak boundary-layer instability, and some MLCIN should tend to limit the threat for surface-based thunderstorms. Still, forecast instability trends will be closely monitored for locations east of the current Marginal Risk. ..Gleason.. 12/22/2023 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1124 AM CST Fri Dec 22 2023 Valid 231200Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTHERN HIGH PLAINS... ...SUMMARY... Isolated severe thunderstorms capable of producing hail and strong/gusty winds appear possible across parts of the southern High Plains, mainly Saturday afternoon and evening. ...Southern High Plains... Large-scale upper troughing will encompass much of the western states on Saturday. A southern-stream shortwave trough is expected to move eastward from the Southwest across the southern/central High Plans through the period. Large-scale ascent preceding this shortwave trough will encourage the development of a lee surface low across eastern CO through the day, with the low then ejecting eastward across KS Saturday night through early Sunday morning. Low-level moisture will continue to stream northward ahead of the surface low and a Pacific cold front advancing eastward across the southern High Plains. Widespread cloudiness and limited daytime heating should temper the degree of instability that can develop through Saturday afternoon across the southern High Plains. Even so, cooling mid-level temperatures and somewhat steepened lapse rates aloft ahead of the upper trough should aid in at least weak destabilization across parts of far eastern NM into west TX and the TX Panhandle by late Saturday afternoon. MLCAPE generally ranging from 500-750 J/kg should prove adequate in tandem with strong deep-layer shear of 40-50 kt to support organized updrafts. Convection that forms along or just ahead of the Pacific cold front may be initially discrete and pose a threat for isolated severe hail given the favorable shear. With time, upscale growth into one or more clusters appears probable through Saturday evening as thunderstorms spread east-northeastward across west TX and the TX Panhandle. Even though low-level lapse rates should remain modest with limited daytime heating, some threat for strong to locally severe wind gusts may still exist as this mode transition occurs. Somewhat greater low-level moisture, with surface dewpoints in the upper 50s to low 60s, should be in place farther east into OK and north/central TX. One or more thunderstorm clusters should move across these areas Saturday night into early Sunday morning. While both low-level and deep-layer shear appear favorable for organized convection, poor lapse rates, weak boundary-layer instability, and some MLCIN should tend to limit the threat for surface-based thunderstorms. Still, forecast instability trends will be closely monitored for locations east of the current Marginal Risk. ..Gleason.. 12/22/2023 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1022 AM CST Fri Dec 22 2023 Valid 221630Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING ACROSS PARTS OF SOUTHEAST CALIFORNIA AND SOUTHERN ARIZONA... ...SUMMARY... Isolated large hail and strong-severe gusts are possible from midday into evening across parts of southern Arizona and vicinity. ...Southwest US... Morning water vapor loop shows a compact upper-low off the coast to the southwest of San Diego, CA. A 70+ knot mid-level jet max is rotating around the base of the low, and will overspread northwest Mexico and into southern AZ tonight. Widespread clouds and scattered precipitation will limit heating/destabilization in most parts of AZ today. However, visible imagery shows broken cloud cover over southern CA just ahead of the upper low. Steep mid-level lapse rates and cold temperatures aloft may result in sufficient CAPE for a few robust updrafts this afternoon. CAM guidance suggests the main area of concern is along and east of the Colorado River valley. A few storms may produce hail and gusty wind in this region this afternoon. Other strong storms may form in the low-level warm-advection zone and beneath the strong winds aloft across southeast AZ after dark. This area will see very little daytime heating or destabilization, but stronger vertical shear profiles and sufficient CAPE could encourage an organized storm or two capable of gusty winds. ..Hart/Wendt.. 12/22/2023 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1022 AM CST Fri Dec 22 2023 Valid 221630Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING ACROSS PARTS OF SOUTHEAST CALIFORNIA AND SOUTHERN ARIZONA... ...SUMMARY... Isolated large hail and strong-severe gusts are possible from midday into evening across parts of southern Arizona and vicinity. ...Southwest US... Morning water vapor loop shows a compact upper-low off the coast to the southwest of San Diego, CA. A 70+ knot mid-level jet max is rotating around the base of the low, and will overspread northwest Mexico and into southern AZ tonight. Widespread clouds and scattered precipitation will limit heating/destabilization in most parts of AZ today. However, visible imagery shows broken cloud cover over southern CA just ahead of the upper low. Steep mid-level lapse rates and cold temperatures aloft may result in sufficient CAPE for a few robust updrafts this afternoon. CAM guidance suggests the main area of concern is along and east of the Colorado River valley. A few storms may produce hail and gusty wind in this region this afternoon. Other strong storms may form in the low-level warm-advection zone and beneath the strong winds aloft across southeast AZ after dark. This area will see very little daytime heating or destabilization, but stronger vertical shear profiles and sufficient CAPE could encourage an organized storm or two capable of gusty winds. ..Hart/Wendt.. 12/22/2023 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1022 AM CST Fri Dec 22 2023 Valid 221630Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING ACROSS PARTS OF SOUTHEAST CALIFORNIA AND SOUTHERN ARIZONA... ...SUMMARY... Isolated large hail and strong-severe gusts are possible from midday into evening across parts of southern Arizona and vicinity. ...Southwest US... Morning water vapor loop shows a compact upper-low off the coast to the southwest of San Diego, CA. A 70+ knot mid-level jet max is rotating around the base of the low, and will overspread northwest Mexico and into southern AZ tonight. Widespread clouds and scattered precipitation will limit heating/destabilization in most parts of AZ today. However, visible imagery shows broken cloud cover over southern CA just ahead of the upper low. Steep mid-level lapse rates and cold temperatures aloft may result in sufficient CAPE for a few robust updrafts this afternoon. CAM guidance suggests the main area of concern is along and east of the Colorado River valley. A few storms may produce hail and gusty wind in this region this afternoon. Other strong storms may form in the low-level warm-advection zone and beneath the strong winds aloft across southeast AZ after dark. This area will see very little daytime heating or destabilization, but stronger vertical shear profiles and sufficient CAPE could encourage an organized storm or two capable of gusty winds. ..Hart/Wendt.. 12/22/2023 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1022 AM CST Fri Dec 22 2023 Valid 221630Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING ACROSS PARTS OF SOUTHEAST CALIFORNIA AND SOUTHERN ARIZONA... ...SUMMARY... Isolated large hail and strong-severe gusts are possible from midday into evening across parts of southern Arizona and vicinity. ...Southwest US... Morning water vapor loop shows a compact upper-low off the coast to the southwest of San Diego, CA. A 70+ knot mid-level jet max is rotating around the base of the low, and will overspread northwest Mexico and into southern AZ tonight. Widespread clouds and scattered precipitation will limit heating/destabilization in most parts of AZ today. However, visible imagery shows broken cloud cover over southern CA just ahead of the upper low. Steep mid-level lapse rates and cold temperatures aloft may result in sufficient CAPE for a few robust updrafts this afternoon. CAM guidance suggests the main area of concern is along and east of the Colorado River valley. A few storms may produce hail and gusty wind in this region this afternoon. Other strong storms may form in the low-level warm-advection zone and beneath the strong winds aloft across southeast AZ after dark. This area will see very little daytime heating or destabilization, but stronger vertical shear profiles and sufficient CAPE could encourage an organized storm or two capable of gusty winds. ..Hart/Wendt.. 12/22/2023 Read more