Severe Storms

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1122 AM CST Fri Dec 13 2024 Valid 141200Z - 151200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected on Saturday. ...Central/Southern Plains to the Lower Ohio Valley... An upper low will move from the central Plains to the Great Lakes on Saturday. A surface low will weaken through the day as this trough advances northeast. A sustained low-level jet will advance from the Ozarks to the Ohio Valley and provide ample ascent and elevated instability for thunderstorm activity through the day. Instability should remain too limited for any severe weather threat from this elevated convection. Weak surface heating across the ArkLaTex may be sufficient for a few surface-based storms. However, instability will be weak and ascent will mostly be focused north of this area. Therefore, no severe storms are anticipated. ...California to the Pacific Northwest... A trough approaching the Pacific coast on Saturday will result in scattered thunderstorm activity from southwest Washington to central California as cooler air aloft steepens lapse rates across the region. Overall, weak instability combined with relatively weak low-level flow should preclude any severe weather threat. A more focused low-level jet will result in stronger low-level flow across the central California Coast late Saturday morning into the early afternoon. However, during this period, forecast soundings indicate minimal to no instability which should preclude any severe weather concern. ..Bentley.. 12/13/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1122 AM CST Fri Dec 13 2024 Valid 141200Z - 151200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected on Saturday. ...Central/Southern Plains to the Lower Ohio Valley... An upper low will move from the central Plains to the Great Lakes on Saturday. A surface low will weaken through the day as this trough advances northeast. A sustained low-level jet will advance from the Ozarks to the Ohio Valley and provide ample ascent and elevated instability for thunderstorm activity through the day. Instability should remain too limited for any severe weather threat from this elevated convection. Weak surface heating across the ArkLaTex may be sufficient for a few surface-based storms. However, instability will be weak and ascent will mostly be focused north of this area. Therefore, no severe storms are anticipated. ...California to the Pacific Northwest... A trough approaching the Pacific coast on Saturday will result in scattered thunderstorm activity from southwest Washington to central California as cooler air aloft steepens lapse rates across the region. Overall, weak instability combined with relatively weak low-level flow should preclude any severe weather threat. A more focused low-level jet will result in stronger low-level flow across the central California Coast late Saturday morning into the early afternoon. However, during this period, forecast soundings indicate minimal to no instability which should preclude any severe weather concern. ..Bentley.. 12/13/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1122 AM CST Fri Dec 13 2024 Valid 141200Z - 151200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected on Saturday. ...Central/Southern Plains to the Lower Ohio Valley... An upper low will move from the central Plains to the Great Lakes on Saturday. A surface low will weaken through the day as this trough advances northeast. A sustained low-level jet will advance from the Ozarks to the Ohio Valley and provide ample ascent and elevated instability for thunderstorm activity through the day. Instability should remain too limited for any severe weather threat from this elevated convection. Weak surface heating across the ArkLaTex may be sufficient for a few surface-based storms. However, instability will be weak and ascent will mostly be focused north of this area. Therefore, no severe storms are anticipated. ...California to the Pacific Northwest... A trough approaching the Pacific coast on Saturday will result in scattered thunderstorm activity from southwest Washington to central California as cooler air aloft steepens lapse rates across the region. Overall, weak instability combined with relatively weak low-level flow should preclude any severe weather threat. A more focused low-level jet will result in stronger low-level flow across the central California Coast late Saturday morning into the early afternoon. However, during this period, forecast soundings indicate minimal to no instability which should preclude any severe weather concern. ..Bentley.. 12/13/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1122 AM CST Fri Dec 13 2024 Valid 141200Z - 151200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected on Saturday. ...Central/Southern Plains to the Lower Ohio Valley... An upper low will move from the central Plains to the Great Lakes on Saturday. A surface low will weaken through the day as this trough advances northeast. A sustained low-level jet will advance from the Ozarks to the Ohio Valley and provide ample ascent and elevated instability for thunderstorm activity through the day. Instability should remain too limited for any severe weather threat from this elevated convection. Weak surface heating across the ArkLaTex may be sufficient for a few surface-based storms. However, instability will be weak and ascent will mostly be focused north of this area. Therefore, no severe storms are anticipated. ...California to the Pacific Northwest... A trough approaching the Pacific coast on Saturday will result in scattered thunderstorm activity from southwest Washington to central California as cooler air aloft steepens lapse rates across the region. Overall, weak instability combined with relatively weak low-level flow should preclude any severe weather threat. A more focused low-level jet will result in stronger low-level flow across the central California Coast late Saturday morning into the early afternoon. However, during this period, forecast soundings indicate minimal to no instability which should preclude any severe weather concern. ..Bentley.. 12/13/2024 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1042 AM CST Fri Dec 13 2024 Valid 131700Z - 141200Z Dry and gusty conditions are possible in parts of southeast Arizona/southwest New Mexico where portions of the mid-level jet will enhance surface winds. The elevated area was expanded into these areas. See the previous discussion for additional details. ..Wendt.. 12/13/2024 .PREV DISCUSSION... /ISSUED 0153 AM CST Fri Dec 13 2024/ ...Synopsis... A progressive mid-level shortwave trough is forecast to traverse the southern Rockies today, reaching central NM by peak heating. In response to the arrival of the wave, a lee cyclone across east/southeast CO will deepen, intensifying westerly downslope surface winds over the southern High Plains and lee of the Rockies. Sustained winds of 20-25 mph (gusting to 35-40 mph) are possible, given deep mixing and the approach of a 45-55 knot mid-level jet. The downslope trajectories, deep mixing and mild temperatures will support afternoon RH values of 12-15%. Despite several hours of elevated to critical meteorological conditions, the main limiting factor appears to be the lack of critically dry fuels. With seasonal ERC values of 60-80%, area fuels should be capable of supporting some elevated fire-weather risk, though conditions do not appear favorable for more widespread critical concerns. ...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 1042 AM CST Fri Dec 13 2024 Valid 131700Z - 141200Z Dry and gusty conditions are possible in parts of southeast Arizona/southwest New Mexico where portions of the mid-level jet will enhance surface winds. The elevated area was expanded into these areas. See the previous discussion for additional details. ..Wendt.. 12/13/2024 .PREV DISCUSSION... /ISSUED 0153 AM CST Fri Dec 13 2024/ ...Synopsis... A progressive mid-level shortwave trough is forecast to traverse the southern Rockies today, reaching central NM by peak heating. In response to the arrival of the wave, a lee cyclone across east/southeast CO will deepen, intensifying westerly downslope surface winds over the southern High Plains and lee of the Rockies. Sustained winds of 20-25 mph (gusting to 35-40 mph) are possible, given deep mixing and the approach of a 45-55 knot mid-level jet. The downslope trajectories, deep mixing and mild temperatures will support afternoon RH values of 12-15%. Despite several hours of elevated to critical meteorological conditions, the main limiting factor appears to be the lack of critically dry fuels. With seasonal ERC values of 60-80%, area fuels should be capable of supporting some elevated fire-weather risk, though conditions do not appear favorable for more widespread critical concerns. ...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 1042 AM CST Fri Dec 13 2024 Valid 131700Z - 141200Z Dry and gusty conditions are possible in parts of southeast Arizona/southwest New Mexico where portions of the mid-level jet will enhance surface winds. The elevated area was expanded into these areas. See the previous discussion for additional details. ..Wendt.. 12/13/2024 .PREV DISCUSSION... /ISSUED 0153 AM CST Fri Dec 13 2024/ ...Synopsis... A progressive mid-level shortwave trough is forecast to traverse the southern Rockies today, reaching central NM by peak heating. In response to the arrival of the wave, a lee cyclone across east/southeast CO will deepen, intensifying westerly downslope surface winds over the southern High Plains and lee of the Rockies. Sustained winds of 20-25 mph (gusting to 35-40 mph) are possible, given deep mixing and the approach of a 45-55 knot mid-level jet. The downslope trajectories, deep mixing and mild temperatures will support afternoon RH values of 12-15%. Despite several hours of elevated to critical meteorological conditions, the main limiting factor appears to be the lack of critically dry fuels. With seasonal ERC values of 60-80%, area fuels should be capable of supporting some elevated fire-weather risk, though conditions do not appear favorable for more widespread critical concerns. ...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 1042 AM CST Fri Dec 13 2024 Valid 131700Z - 141200Z Dry and gusty conditions are possible in parts of southeast Arizona/southwest New Mexico where portions of the mid-level jet will enhance surface winds. The elevated area was expanded into these areas. See the previous discussion for additional details. ..Wendt.. 12/13/2024 .PREV DISCUSSION... /ISSUED 0153 AM CST Fri Dec 13 2024/ ...Synopsis... A progressive mid-level shortwave trough is forecast to traverse the southern Rockies today, reaching central NM by peak heating. In response to the arrival of the wave, a lee cyclone across east/southeast CO will deepen, intensifying westerly downslope surface winds over the southern High Plains and lee of the Rockies. Sustained winds of 20-25 mph (gusting to 35-40 mph) are possible, given deep mixing and the approach of a 45-55 knot mid-level jet. The downslope trajectories, deep mixing and mild temperatures will support afternoon RH values of 12-15%. Despite several hours of elevated to critical meteorological conditions, the main limiting factor appears to be the lack of critically dry fuels. With seasonal ERC values of 60-80%, area fuels should be capable of supporting some elevated fire-weather risk, though conditions do not appear favorable for more widespread critical concerns. ...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 1042 AM CST Fri Dec 13 2024 Valid 131700Z - 141200Z Dry and gusty conditions are possible in parts of southeast Arizona/southwest New Mexico where portions of the mid-level jet will enhance surface winds. The elevated area was expanded into these areas. See the previous discussion for additional details. ..Wendt.. 12/13/2024 .PREV DISCUSSION... /ISSUED 0153 AM CST Fri Dec 13 2024/ ...Synopsis... A progressive mid-level shortwave trough is forecast to traverse the southern Rockies today, reaching central NM by peak heating. In response to the arrival of the wave, a lee cyclone across east/southeast CO will deepen, intensifying westerly downslope surface winds over the southern High Plains and lee of the Rockies. Sustained winds of 20-25 mph (gusting to 35-40 mph) are possible, given deep mixing and the approach of a 45-55 knot mid-level jet. The downslope trajectories, deep mixing and mild temperatures will support afternoon RH values of 12-15%. Despite several hours of elevated to critical meteorological conditions, the main limiting factor appears to be the lack of critically dry fuels. With seasonal ERC values of 60-80%, area fuels should be capable of supporting some elevated fire-weather risk, though conditions do not appear favorable for more widespread critical concerns. ...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 1042 AM CST Fri Dec 13 2024 Valid 131700Z - 141200Z Dry and gusty conditions are possible in parts of southeast Arizona/southwest New Mexico where portions of the mid-level jet will enhance surface winds. The elevated area was expanded into these areas. See the previous discussion for additional details. ..Wendt.. 12/13/2024 .PREV DISCUSSION... /ISSUED 0153 AM CST Fri Dec 13 2024/ ...Synopsis... A progressive mid-level shortwave trough is forecast to traverse the southern Rockies today, reaching central NM by peak heating. In response to the arrival of the wave, a lee cyclone across east/southeast CO will deepen, intensifying westerly downslope surface winds over the southern High Plains and lee of the Rockies. Sustained winds of 20-25 mph (gusting to 35-40 mph) are possible, given deep mixing and the approach of a 45-55 knot mid-level jet. The downslope trajectories, deep mixing and mild temperatures will support afternoon RH values of 12-15%. Despite several hours of elevated to critical meteorological conditions, the main limiting factor appears to be the lack of critically dry fuels. With seasonal ERC values of 60-80%, area fuels should be capable of supporting some elevated fire-weather risk, though conditions do not appear favorable for more widespread critical concerns. ...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 1042 AM CST Fri Dec 13 2024 Valid 131700Z - 141200Z Dry and gusty conditions are possible in parts of southeast Arizona/southwest New Mexico where portions of the mid-level jet will enhance surface winds. The elevated area was expanded into these areas. See the previous discussion for additional details. ..Wendt.. 12/13/2024 .PREV DISCUSSION... /ISSUED 0153 AM CST Fri Dec 13 2024/ ...Synopsis... A progressive mid-level shortwave trough is forecast to traverse the southern Rockies today, reaching central NM by peak heating. In response to the arrival of the wave, a lee cyclone across east/southeast CO will deepen, intensifying westerly downslope surface winds over the southern High Plains and lee of the Rockies. Sustained winds of 20-25 mph (gusting to 35-40 mph) are possible, given deep mixing and the approach of a 45-55 knot mid-level jet. The downslope trajectories, deep mixing and mild temperatures will support afternoon RH values of 12-15%. Despite several hours of elevated to critical meteorological conditions, the main limiting factor appears to be the lack of critically dry fuels. With seasonal ERC values of 60-80%, area fuels should be capable of supporting some elevated fire-weather risk, though conditions do not appear favorable for more widespread critical concerns. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1030 AM CST Fri Dec 13 2024 Valid 131630Z - 141200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe thunderstorms appear unlikely through tonight. ...Southern/Central Plains into the Ozarks/ArkLaTex... A compact shortwave trough over the Great Basin this morning will move eastward across the southern/central Plains through tonight while gradually amplifying. Related low-level mass response will encourage the northward advance of modified Gulf moisture across parts of the southern/central Plains ahead of a weak surface low and cold front forecast to track from the central High Plains to eastern KS/OK by early Saturday morning. Given the limited/shallow nature of the low-level moisture return, current expectations are for any convection that develops late tonight in the warm advection regime to remain elevated. MUCAPE is generally forecast to remain less than 1000 J/kg, which should tend to limit the prospect for large hail with these elevated thunderstorms. Even so, cold mid-level temperatures associated with the ejecting shortwave trough and sufficient shear through the cloud-bearing layer may support some risk for small hail with the strongest cores. This activity is expected to spread eastward from the southern/central Plains into the Ozarks/ArkLaTex vicinity through the end of the period. ...Northern California... An upper trough will approach the West Coast late tonight into early Saturday morning. Associated low-level warm/moist advection will occur ahead of a weak surface front, with a broad area of precipitation forecast across parts of northern CA and the Pacific Northwest. Gradual cooling of mid-level temperatures will occur as the upper trough approaches, which may support meager MUCAPE across parts of northern CA for the last few hours of the period (early Saturday morning). Isolated lightning flashes may occur with low-topped convection along/near the front, with overall thunderstorm probabilities around 10 percent. ..Gleason/Halbert.. 12/13/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1030 AM CST Fri Dec 13 2024 Valid 131630Z - 141200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe thunderstorms appear unlikely through tonight. ...Southern/Central Plains into the Ozarks/ArkLaTex... A compact shortwave trough over the Great Basin this morning will move eastward across the southern/central Plains through tonight while gradually amplifying. Related low-level mass response will encourage the northward advance of modified Gulf moisture across parts of the southern/central Plains ahead of a weak surface low and cold front forecast to track from the central High Plains to eastern KS/OK by early Saturday morning. Given the limited/shallow nature of the low-level moisture return, current expectations are for any convection that develops late tonight in the warm advection regime to remain elevated. MUCAPE is generally forecast to remain less than 1000 J/kg, which should tend to limit the prospect for large hail with these elevated thunderstorms. Even so, cold mid-level temperatures associated with the ejecting shortwave trough and sufficient shear through the cloud-bearing layer may support some risk for small hail with the strongest cores. This activity is expected to spread eastward from the southern/central Plains into the Ozarks/ArkLaTex vicinity through the end of the period. ...Northern California... An upper trough will approach the West Coast late tonight into early Saturday morning. Associated low-level warm/moist advection will occur ahead of a weak surface front, with a broad area of precipitation forecast across parts of northern CA and the Pacific Northwest. Gradual cooling of mid-level temperatures will occur as the upper trough approaches, which may support meager MUCAPE across parts of northern CA for the last few hours of the period (early Saturday morning). Isolated lightning flashes may occur with low-topped convection along/near the front, with overall thunderstorm probabilities around 10 percent. ..Gleason/Halbert.. 12/13/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1030 AM CST Fri Dec 13 2024 Valid 131630Z - 141200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe thunderstorms appear unlikely through tonight. ...Southern/Central Plains into the Ozarks/ArkLaTex... A compact shortwave trough over the Great Basin this morning will move eastward across the southern/central Plains through tonight while gradually amplifying. Related low-level mass response will encourage the northward advance of modified Gulf moisture across parts of the southern/central Plains ahead of a weak surface low and cold front forecast to track from the central High Plains to eastern KS/OK by early Saturday morning. Given the limited/shallow nature of the low-level moisture return, current expectations are for any convection that develops late tonight in the warm advection regime to remain elevated. MUCAPE is generally forecast to remain less than 1000 J/kg, which should tend to limit the prospect for large hail with these elevated thunderstorms. Even so, cold mid-level temperatures associated with the ejecting shortwave trough and sufficient shear through the cloud-bearing layer may support some risk for small hail with the strongest cores. This activity is expected to spread eastward from the southern/central Plains into the Ozarks/ArkLaTex vicinity through the end of the period. ...Northern California... An upper trough will approach the West Coast late tonight into early Saturday morning. Associated low-level warm/moist advection will occur ahead of a weak surface front, with a broad area of precipitation forecast across parts of northern CA and the Pacific Northwest. Gradual cooling of mid-level temperatures will occur as the upper trough approaches, which may support meager MUCAPE across parts of northern CA for the last few hours of the period (early Saturday morning). Isolated lightning flashes may occur with low-topped convection along/near the front, with overall thunderstorm probabilities around 10 percent. ..Gleason/Halbert.. 12/13/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1030 AM CST Fri Dec 13 2024 Valid 131630Z - 141200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe thunderstorms appear unlikely through tonight. ...Southern/Central Plains into the Ozarks/ArkLaTex... A compact shortwave trough over the Great Basin this morning will move eastward across the southern/central Plains through tonight while gradually amplifying. Related low-level mass response will encourage the northward advance of modified Gulf moisture across parts of the southern/central Plains ahead of a weak surface low and cold front forecast to track from the central High Plains to eastern KS/OK by early Saturday morning. Given the limited/shallow nature of the low-level moisture return, current expectations are for any convection that develops late tonight in the warm advection regime to remain elevated. MUCAPE is generally forecast to remain less than 1000 J/kg, which should tend to limit the prospect for large hail with these elevated thunderstorms. Even so, cold mid-level temperatures associated with the ejecting shortwave trough and sufficient shear through the cloud-bearing layer may support some risk for small hail with the strongest cores. This activity is expected to spread eastward from the southern/central Plains into the Ozarks/ArkLaTex vicinity through the end of the period. ...Northern California... An upper trough will approach the West Coast late tonight into early Saturday morning. Associated low-level warm/moist advection will occur ahead of a weak surface front, with a broad area of precipitation forecast across parts of northern CA and the Pacific Northwest. Gradual cooling of mid-level temperatures will occur as the upper trough approaches, which may support meager MUCAPE across parts of northern CA for the last few hours of the period (early Saturday morning). Isolated lightning flashes may occur with low-topped convection along/near the front, with overall thunderstorm probabilities around 10 percent. ..Gleason/Halbert.. 12/13/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1030 AM CST Fri Dec 13 2024 Valid 131630Z - 141200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe thunderstorms appear unlikely through tonight. ...Southern/Central Plains into the Ozarks/ArkLaTex... A compact shortwave trough over the Great Basin this morning will move eastward across the southern/central Plains through tonight while gradually amplifying. Related low-level mass response will encourage the northward advance of modified Gulf moisture across parts of the southern/central Plains ahead of a weak surface low and cold front forecast to track from the central High Plains to eastern KS/OK by early Saturday morning. Given the limited/shallow nature of the low-level moisture return, current expectations are for any convection that develops late tonight in the warm advection regime to remain elevated. MUCAPE is generally forecast to remain less than 1000 J/kg, which should tend to limit the prospect for large hail with these elevated thunderstorms. Even so, cold mid-level temperatures associated with the ejecting shortwave trough and sufficient shear through the cloud-bearing layer may support some risk for small hail with the strongest cores. This activity is expected to spread eastward from the southern/central Plains into the Ozarks/ArkLaTex vicinity through the end of the period. ...Northern California... An upper trough will approach the West Coast late tonight into early Saturday morning. Associated low-level warm/moist advection will occur ahead of a weak surface front, with a broad area of precipitation forecast across parts of northern CA and the Pacific Northwest. Gradual cooling of mid-level temperatures will occur as the upper trough approaches, which may support meager MUCAPE across parts of northern CA for the last few hours of the period (early Saturday morning). Isolated lightning flashes may occur with low-topped convection along/near the front, with overall thunderstorm probabilities around 10 percent. ..Gleason/Halbert.. 12/13/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1030 AM CST Fri Dec 13 2024 Valid 131630Z - 141200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe thunderstorms appear unlikely through tonight. ...Southern/Central Plains into the Ozarks/ArkLaTex... A compact shortwave trough over the Great Basin this morning will move eastward across the southern/central Plains through tonight while gradually amplifying. Related low-level mass response will encourage the northward advance of modified Gulf moisture across parts of the southern/central Plains ahead of a weak surface low and cold front forecast to track from the central High Plains to eastern KS/OK by early Saturday morning. Given the limited/shallow nature of the low-level moisture return, current expectations are for any convection that develops late tonight in the warm advection regime to remain elevated. MUCAPE is generally forecast to remain less than 1000 J/kg, which should tend to limit the prospect for large hail with these elevated thunderstorms. Even so, cold mid-level temperatures associated with the ejecting shortwave trough and sufficient shear through the cloud-bearing layer may support some risk for small hail with the strongest cores. This activity is expected to spread eastward from the southern/central Plains into the Ozarks/ArkLaTex vicinity through the end of the period. ...Northern California... An upper trough will approach the West Coast late tonight into early Saturday morning. Associated low-level warm/moist advection will occur ahead of a weak surface front, with a broad area of precipitation forecast across parts of northern CA and the Pacific Northwest. Gradual cooling of mid-level temperatures will occur as the upper trough approaches, which may support meager MUCAPE across parts of northern CA for the last few hours of the period (early Saturday morning). Isolated lightning flashes may occur with low-topped convection along/near the front, with overall thunderstorm probabilities around 10 percent. ..Gleason/Halbert.. 12/13/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1030 AM CST Fri Dec 13 2024 Valid 131630Z - 141200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe thunderstorms appear unlikely through tonight. ...Southern/Central Plains into the Ozarks/ArkLaTex... A compact shortwave trough over the Great Basin this morning will move eastward across the southern/central Plains through tonight while gradually amplifying. Related low-level mass response will encourage the northward advance of modified Gulf moisture across parts of the southern/central Plains ahead of a weak surface low and cold front forecast to track from the central High Plains to eastern KS/OK by early Saturday morning. Given the limited/shallow nature of the low-level moisture return, current expectations are for any convection that develops late tonight in the warm advection regime to remain elevated. MUCAPE is generally forecast to remain less than 1000 J/kg, which should tend to limit the prospect for large hail with these elevated thunderstorms. Even so, cold mid-level temperatures associated with the ejecting shortwave trough and sufficient shear through the cloud-bearing layer may support some risk for small hail with the strongest cores. This activity is expected to spread eastward from the southern/central Plains into the Ozarks/ArkLaTex vicinity through the end of the period. ...Northern California... An upper trough will approach the West Coast late tonight into early Saturday morning. Associated low-level warm/moist advection will occur ahead of a weak surface front, with a broad area of precipitation forecast across parts of northern CA and the Pacific Northwest. Gradual cooling of mid-level temperatures will occur as the upper trough approaches, which may support meager MUCAPE across parts of northern CA for the last few hours of the period (early Saturday morning). Isolated lightning flashes may occur with low-topped convection along/near the front, with overall thunderstorm probabilities around 10 percent. ..Gleason/Halbert.. 12/13/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0643 AM CST Fri Dec 13 2024 Valid 131300Z - 141200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected through tonight. ...Synopsis/Discussion... As heights rise in the East following the departure of a substantial synoptic-scale trough, two strong shortwave troughs will progress through the midlatitude westerlies upstream, and influence thunder potential across the western/central CONUS: 1. A leading perturbation -- now apparent over the eastern Great Basin and southern ID -- should extend from southeastern WY across east-central CO to eastern NM by 00Z. By the end of the period, the trough should reach central portions of SD/NE/KS and northwestern OK, while deepening. A closed 500-mb low may develop on the trough, either then or within a few hours into day 2, over south-central/ southeastern NE. Strong, foregoing low-level warm advection and moisture transport will persist through the period, atop a relatively stable near-surface layer. Increasing thunderstorm coverage is expected after about 06Z from the middle/upper TX Coast to the lower Missouri Valley, as increasingly moist parcels above that stable layer reach LFC. This will occur in concordance with steepening low/middle-level lapse rates and decreasing MUCINH, mainly related to the warm advection (but also late DCVA over northwestern parts of the outlook area). Small hail may fall from the strongest cells; however, forecast soundings indicate effective shear, buoyancy and inflow-layer moisture content should be too small for a severe threat. 2. The trailing shortwave trough -- initially evident in moisture- channel imagery over the North Pacific around 40N150W -- will move rapidly eastward and amplify, with preceding large-scale ascent reaching the CA/OR coastline after 06Z on either side of a low-level cold front. While lapse rates in the frontal band should be modest, and buoyancy meager, areas of MUCAPE around 50-200 J/kg, rooted near 700 mb -- may extend deeply enough into suitable icing layers to support isolated lightning. ..Edwards/Goss.. 12/13/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0643 AM CST Fri Dec 13 2024 Valid 131300Z - 141200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected through tonight. ...Synopsis/Discussion... As heights rise in the East following the departure of a substantial synoptic-scale trough, two strong shortwave troughs will progress through the midlatitude westerlies upstream, and influence thunder potential across the western/central CONUS: 1. A leading perturbation -- now apparent over the eastern Great Basin and southern ID -- should extend from southeastern WY across east-central CO to eastern NM by 00Z. By the end of the period, the trough should reach central portions of SD/NE/KS and northwestern OK, while deepening. A closed 500-mb low may develop on the trough, either then or within a few hours into day 2, over south-central/ southeastern NE. Strong, foregoing low-level warm advection and moisture transport will persist through the period, atop a relatively stable near-surface layer. Increasing thunderstorm coverage is expected after about 06Z from the middle/upper TX Coast to the lower Missouri Valley, as increasingly moist parcels above that stable layer reach LFC. This will occur in concordance with steepening low/middle-level lapse rates and decreasing MUCINH, mainly related to the warm advection (but also late DCVA over northwestern parts of the outlook area). Small hail may fall from the strongest cells; however, forecast soundings indicate effective shear, buoyancy and inflow-layer moisture content should be too small for a severe threat. 2. The trailing shortwave trough -- initially evident in moisture- channel imagery over the North Pacific around 40N150W -- will move rapidly eastward and amplify, with preceding large-scale ascent reaching the CA/OR coastline after 06Z on either side of a low-level cold front. While lapse rates in the frontal band should be modest, and buoyancy meager, areas of MUCAPE around 50-200 J/kg, rooted near 700 mb -- may extend deeply enough into suitable icing layers to support isolated lightning. ..Edwards/Goss.. 12/13/2024 Read more