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SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1117 AM CST Mon Feb 19 2024 Valid 201200Z - 211200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Widely scattered, generally weak, thunderstorm activity is possible Tuesday into Tuesday night across parts of Pacific Coast states into Great Basin, with little risk for severe weather. ...Discussion... Models indicate that an initially broad and deep cyclone will undergo substantive further weakening later today through late Tuesday night, while migrating northward offshore of the Pacific coast, toward the Vancouver Island/coastal Washington vicinity. Upstream, a significant short wave trough is forecast to gradually split to the southeast of the Aleutians, with the more vigorous southern perturbation beginning to dig through the mid-latitude eastern Pacific. As this occurs, a weak downstream mid-level high may attempt to form near the northern British Columbia coast, while remnant mid-level troughing in the branch of westerlies across the southern mid- and subtropical latitudes begins to progress inland of the Pacific coast. Farther east, large-scale mid-level ridging appears likely to shift across and east of the southern Rockies and northern Mexican plateau, while downstream troughing shifts offshore of the southern Atlantic Seaboard. This regime may undergo some further amplification, with perhaps renewed surface cyclogenesis commencing across the southwestern Atlantic by the end of the period. Low-level cooling and drying in the wake of the lead mid-level troughing has stabilized much of the Gulf of Mexico. While models do suggest that modest modification may commence in at least a narrow corridor across the western Gulf of Mexico into northwestern Gulf coastal areas, it appears that the moistening boundary-layer will remain shallow, and strongly capped by warm eastward advecting lower/mid-tropospheric air. Across the Pacific coast into the Great Basin, ongoing low/mid-level moistening, coupled with continuing cooling aloft through the day Tuesday, may contribute to sufficient destabilization with daytime heating to support widely scattered convection capable of producing lightning. However, latest model output generally suggests that the higher probabilities for thunderstorm development will be focused near the mid-level cold core offshore the southern California/northern Baja coast, before approaching coastal areas late Tuesday night. ..Kerr.. 02/19/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1117 AM CST Mon Feb 19 2024 Valid 201200Z - 211200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Widely scattered, generally weak, thunderstorm activity is possible Tuesday into Tuesday night across parts of Pacific Coast states into Great Basin, with little risk for severe weather. ...Discussion... Models indicate that an initially broad and deep cyclone will undergo substantive further weakening later today through late Tuesday night, while migrating northward offshore of the Pacific coast, toward the Vancouver Island/coastal Washington vicinity. Upstream, a significant short wave trough is forecast to gradually split to the southeast of the Aleutians, with the more vigorous southern perturbation beginning to dig through the mid-latitude eastern Pacific. As this occurs, a weak downstream mid-level high may attempt to form near the northern British Columbia coast, while remnant mid-level troughing in the branch of westerlies across the southern mid- and subtropical latitudes begins to progress inland of the Pacific coast. Farther east, large-scale mid-level ridging appears likely to shift across and east of the southern Rockies and northern Mexican plateau, while downstream troughing shifts offshore of the southern Atlantic Seaboard. This regime may undergo some further amplification, with perhaps renewed surface cyclogenesis commencing across the southwestern Atlantic by the end of the period. Low-level cooling and drying in the wake of the lead mid-level troughing has stabilized much of the Gulf of Mexico. While models do suggest that modest modification may commence in at least a narrow corridor across the western Gulf of Mexico into northwestern Gulf coastal areas, it appears that the moistening boundary-layer will remain shallow, and strongly capped by warm eastward advecting lower/mid-tropospheric air. Across the Pacific coast into the Great Basin, ongoing low/mid-level moistening, coupled with continuing cooling aloft through the day Tuesday, may contribute to sufficient destabilization with daytime heating to support widely scattered convection capable of producing lightning. However, latest model output generally suggests that the higher probabilities for thunderstorm development will be focused near the mid-level cold core offshore the southern California/northern Baja coast, before approaching coastal areas late Tuesday night. ..Kerr.. 02/19/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1117 AM CST Mon Feb 19 2024 Valid 201200Z - 211200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Widely scattered, generally weak, thunderstorm activity is possible Tuesday into Tuesday night across parts of Pacific Coast states into Great Basin, with little risk for severe weather. ...Discussion... Models indicate that an initially broad and deep cyclone will undergo substantive further weakening later today through late Tuesday night, while migrating northward offshore of the Pacific coast, toward the Vancouver Island/coastal Washington vicinity. Upstream, a significant short wave trough is forecast to gradually split to the southeast of the Aleutians, with the more vigorous southern perturbation beginning to dig through the mid-latitude eastern Pacific. As this occurs, a weak downstream mid-level high may attempt to form near the northern British Columbia coast, while remnant mid-level troughing in the branch of westerlies across the southern mid- and subtropical latitudes begins to progress inland of the Pacific coast. Farther east, large-scale mid-level ridging appears likely to shift across and east of the southern Rockies and northern Mexican plateau, while downstream troughing shifts offshore of the southern Atlantic Seaboard. This regime may undergo some further amplification, with perhaps renewed surface cyclogenesis commencing across the southwestern Atlantic by the end of the period. Low-level cooling and drying in the wake of the lead mid-level troughing has stabilized much of the Gulf of Mexico. While models do suggest that modest modification may commence in at least a narrow corridor across the western Gulf of Mexico into northwestern Gulf coastal areas, it appears that the moistening boundary-layer will remain shallow, and strongly capped by warm eastward advecting lower/mid-tropospheric air. Across the Pacific coast into the Great Basin, ongoing low/mid-level moistening, coupled with continuing cooling aloft through the day Tuesday, may contribute to sufficient destabilization with daytime heating to support widely scattered convection capable of producing lightning. However, latest model output generally suggests that the higher probabilities for thunderstorm development will be focused near the mid-level cold core offshore the southern California/northern Baja coast, before approaching coastal areas late Tuesday night. ..Kerr.. 02/19/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1117 AM CST Mon Feb 19 2024 Valid 201200Z - 211200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Widely scattered, generally weak, thunderstorm activity is possible Tuesday into Tuesday night across parts of Pacific Coast states into Great Basin, with little risk for severe weather. ...Discussion... Models indicate that an initially broad and deep cyclone will undergo substantive further weakening later today through late Tuesday night, while migrating northward offshore of the Pacific coast, toward the Vancouver Island/coastal Washington vicinity. Upstream, a significant short wave trough is forecast to gradually split to the southeast of the Aleutians, with the more vigorous southern perturbation beginning to dig through the mid-latitude eastern Pacific. As this occurs, a weak downstream mid-level high may attempt to form near the northern British Columbia coast, while remnant mid-level troughing in the branch of westerlies across the southern mid- and subtropical latitudes begins to progress inland of the Pacific coast. Farther east, large-scale mid-level ridging appears likely to shift across and east of the southern Rockies and northern Mexican plateau, while downstream troughing shifts offshore of the southern Atlantic Seaboard. This regime may undergo some further amplification, with perhaps renewed surface cyclogenesis commencing across the southwestern Atlantic by the end of the period. Low-level cooling and drying in the wake of the lead mid-level troughing has stabilized much of the Gulf of Mexico. While models do suggest that modest modification may commence in at least a narrow corridor across the western Gulf of Mexico into northwestern Gulf coastal areas, it appears that the moistening boundary-layer will remain shallow, and strongly capped by warm eastward advecting lower/mid-tropospheric air. Across the Pacific coast into the Great Basin, ongoing low/mid-level moistening, coupled with continuing cooling aloft through the day Tuesday, may contribute to sufficient destabilization with daytime heating to support widely scattered convection capable of producing lightning. However, latest model output generally suggests that the higher probabilities for thunderstorm development will be focused near the mid-level cold core offshore the southern California/northern Baja coast, before approaching coastal areas late Tuesday night. ..Kerr.. 02/19/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1117 AM CST Mon Feb 19 2024 Valid 201200Z - 211200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Widely scattered, generally weak, thunderstorm activity is possible Tuesday into Tuesday night across parts of Pacific Coast states into Great Basin, with little risk for severe weather. ...Discussion... Models indicate that an initially broad and deep cyclone will undergo substantive further weakening later today through late Tuesday night, while migrating northward offshore of the Pacific coast, toward the Vancouver Island/coastal Washington vicinity. Upstream, a significant short wave trough is forecast to gradually split to the southeast of the Aleutians, with the more vigorous southern perturbation beginning to dig through the mid-latitude eastern Pacific. As this occurs, a weak downstream mid-level high may attempt to form near the northern British Columbia coast, while remnant mid-level troughing in the branch of westerlies across the southern mid- and subtropical latitudes begins to progress inland of the Pacific coast. Farther east, large-scale mid-level ridging appears likely to shift across and east of the southern Rockies and northern Mexican plateau, while downstream troughing shifts offshore of the southern Atlantic Seaboard. This regime may undergo some further amplification, with perhaps renewed surface cyclogenesis commencing across the southwestern Atlantic by the end of the period. Low-level cooling and drying in the wake of the lead mid-level troughing has stabilized much of the Gulf of Mexico. While models do suggest that modest modification may commence in at least a narrow corridor across the western Gulf of Mexico into northwestern Gulf coastal areas, it appears that the moistening boundary-layer will remain shallow, and strongly capped by warm eastward advecting lower/mid-tropospheric air. Across the Pacific coast into the Great Basin, ongoing low/mid-level moistening, coupled with continuing cooling aloft through the day Tuesday, may contribute to sufficient destabilization with daytime heating to support widely scattered convection capable of producing lightning. However, latest model output generally suggests that the higher probabilities for thunderstorm development will be focused near the mid-level cold core offshore the southern California/northern Baja coast, before approaching coastal areas late Tuesday night. ..Kerr.. 02/19/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1117 AM CST Mon Feb 19 2024 Valid 201200Z - 211200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Widely scattered, generally weak, thunderstorm activity is possible Tuesday into Tuesday night across parts of Pacific Coast states into Great Basin, with little risk for severe weather. ...Discussion... Models indicate that an initially broad and deep cyclone will undergo substantive further weakening later today through late Tuesday night, while migrating northward offshore of the Pacific coast, toward the Vancouver Island/coastal Washington vicinity. Upstream, a significant short wave trough is forecast to gradually split to the southeast of the Aleutians, with the more vigorous southern perturbation beginning to dig through the mid-latitude eastern Pacific. As this occurs, a weak downstream mid-level high may attempt to form near the northern British Columbia coast, while remnant mid-level troughing in the branch of westerlies across the southern mid- and subtropical latitudes begins to progress inland of the Pacific coast. Farther east, large-scale mid-level ridging appears likely to shift across and east of the southern Rockies and northern Mexican plateau, while downstream troughing shifts offshore of the southern Atlantic Seaboard. This regime may undergo some further amplification, with perhaps renewed surface cyclogenesis commencing across the southwestern Atlantic by the end of the period. Low-level cooling and drying in the wake of the lead mid-level troughing has stabilized much of the Gulf of Mexico. While models do suggest that modest modification may commence in at least a narrow corridor across the western Gulf of Mexico into northwestern Gulf coastal areas, it appears that the moistening boundary-layer will remain shallow, and strongly capped by warm eastward advecting lower/mid-tropospheric air. Across the Pacific coast into the Great Basin, ongoing low/mid-level moistening, coupled with continuing cooling aloft through the day Tuesday, may contribute to sufficient destabilization with daytime heating to support widely scattered convection capable of producing lightning. However, latest model output generally suggests that the higher probabilities for thunderstorm development will be focused near the mid-level cold core offshore the southern California/northern Baja coast, before approaching coastal areas late Tuesday night. ..Kerr.. 02/19/2024 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1045 AM CST Mon Feb 19 2024 Valid 191700Z - 201200Z ...NO CRITICAL AREAS... No changes are needed to the D1 Fire Weather Outlook. See previous discussion below. ..Thornton.. 02/19/2024 .PREV DISCUSSION... /ISSUED 1249 AM CST Mon Feb 19 2024/ ...Synopsis... Fire weather concerns will remain limited for today across the country, though localized concerns are possible in the lee of the central and Southern Rockies. 06 UTC surface observations depict a weak lee trough along the High Plains amid the passage of a low-amplitude upper-level disturbance. This surface feature is expected to migrate east into the Plains today, resulting in modest westerly downslope flow. A stronger pressure gradient yesterday (Sunday) under a similar RH regime (afternoon minimums in the 20-30% range) yielded very localized elevated fire weather conditions based on recent RTMA analyses and surface observations. With somewhat weaker winds expected today, elevated fire weather conditions should remain even more transient/localized within the immediate lee of more prominent terrain features. Elsewhere across the country, dry conditions will persist across parts of the Southeast into the Mid-Atlantic, but weak winds under a broad surface high and marginal fuels should limit wind speeds and the overall fire weather threat. ...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 1045 AM CST Mon Feb 19 2024 Valid 191700Z - 201200Z ...NO CRITICAL AREAS... No changes are needed to the D1 Fire Weather Outlook. See previous discussion below. ..Thornton.. 02/19/2024 .PREV DISCUSSION... /ISSUED 1249 AM CST Mon Feb 19 2024/ ...Synopsis... Fire weather concerns will remain limited for today across the country, though localized concerns are possible in the lee of the central and Southern Rockies. 06 UTC surface observations depict a weak lee trough along the High Plains amid the passage of a low-amplitude upper-level disturbance. This surface feature is expected to migrate east into the Plains today, resulting in modest westerly downslope flow. A stronger pressure gradient yesterday (Sunday) under a similar RH regime (afternoon minimums in the 20-30% range) yielded very localized elevated fire weather conditions based on recent RTMA analyses and surface observations. With somewhat weaker winds expected today, elevated fire weather conditions should remain even more transient/localized within the immediate lee of more prominent terrain features. Elsewhere across the country, dry conditions will persist across parts of the Southeast into the Mid-Atlantic, but weak winds under a broad surface high and marginal fuels should limit wind speeds and the overall fire weather threat. ...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 1045 AM CST Mon Feb 19 2024 Valid 191700Z - 201200Z ...NO CRITICAL AREAS... No changes are needed to the D1 Fire Weather Outlook. See previous discussion below. ..Thornton.. 02/19/2024 .PREV DISCUSSION... /ISSUED 1249 AM CST Mon Feb 19 2024/ ...Synopsis... Fire weather concerns will remain limited for today across the country, though localized concerns are possible in the lee of the central and Southern Rockies. 06 UTC surface observations depict a weak lee trough along the High Plains amid the passage of a low-amplitude upper-level disturbance. This surface feature is expected to migrate east into the Plains today, resulting in modest westerly downslope flow. A stronger pressure gradient yesterday (Sunday) under a similar RH regime (afternoon minimums in the 20-30% range) yielded very localized elevated fire weather conditions based on recent RTMA analyses and surface observations. With somewhat weaker winds expected today, elevated fire weather conditions should remain even more transient/localized within the immediate lee of more prominent terrain features. Elsewhere across the country, dry conditions will persist across parts of the Southeast into the Mid-Atlantic, but weak winds under a broad surface high and marginal fuels should limit wind speeds and the overall fire weather threat. ...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 1045 AM CST Mon Feb 19 2024 Valid 191700Z - 201200Z ...NO CRITICAL AREAS... No changes are needed to the D1 Fire Weather Outlook. See previous discussion below. ..Thornton.. 02/19/2024 .PREV DISCUSSION... /ISSUED 1249 AM CST Mon Feb 19 2024/ ...Synopsis... Fire weather concerns will remain limited for today across the country, though localized concerns are possible in the lee of the central and Southern Rockies. 06 UTC surface observations depict a weak lee trough along the High Plains amid the passage of a low-amplitude upper-level disturbance. This surface feature is expected to migrate east into the Plains today, resulting in modest westerly downslope flow. A stronger pressure gradient yesterday (Sunday) under a similar RH regime (afternoon minimums in the 20-30% range) yielded very localized elevated fire weather conditions based on recent RTMA analyses and surface observations. With somewhat weaker winds expected today, elevated fire weather conditions should remain even more transient/localized within the immediate lee of more prominent terrain features. Elsewhere across the country, dry conditions will persist across parts of the Southeast into the Mid-Atlantic, but weak winds under a broad surface high and marginal fuels should limit wind speeds and the overall fire weather threat. ...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 1045 AM CST Mon Feb 19 2024 Valid 191700Z - 201200Z ...NO CRITICAL AREAS... No changes are needed to the D1 Fire Weather Outlook. See previous discussion below. ..Thornton.. 02/19/2024 .PREV DISCUSSION... /ISSUED 1249 AM CST Mon Feb 19 2024/ ...Synopsis... Fire weather concerns will remain limited for today across the country, though localized concerns are possible in the lee of the central and Southern Rockies. 06 UTC surface observations depict a weak lee trough along the High Plains amid the passage of a low-amplitude upper-level disturbance. This surface feature is expected to migrate east into the Plains today, resulting in modest westerly downslope flow. A stronger pressure gradient yesterday (Sunday) under a similar RH regime (afternoon minimums in the 20-30% range) yielded very localized elevated fire weather conditions based on recent RTMA analyses and surface observations. With somewhat weaker winds expected today, elevated fire weather conditions should remain even more transient/localized within the immediate lee of more prominent terrain features. Elsewhere across the country, dry conditions will persist across parts of the Southeast into the Mid-Atlantic, but weak winds under a broad surface high and marginal fuels should limit wind speeds and the overall fire weather threat. ...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 1045 AM CST Mon Feb 19 2024 Valid 191700Z - 201200Z ...NO CRITICAL AREAS... No changes are needed to the D1 Fire Weather Outlook. See previous discussion below. ..Thornton.. 02/19/2024 .PREV DISCUSSION... /ISSUED 1249 AM CST Mon Feb 19 2024/ ...Synopsis... Fire weather concerns will remain limited for today across the country, though localized concerns are possible in the lee of the central and Southern Rockies. 06 UTC surface observations depict a weak lee trough along the High Plains amid the passage of a low-amplitude upper-level disturbance. This surface feature is expected to migrate east into the Plains today, resulting in modest westerly downslope flow. A stronger pressure gradient yesterday (Sunday) under a similar RH regime (afternoon minimums in the 20-30% range) yielded very localized elevated fire weather conditions based on recent RTMA analyses and surface observations. With somewhat weaker winds expected today, elevated fire weather conditions should remain even more transient/localized within the immediate lee of more prominent terrain features. Elsewhere across the country, dry conditions will persist across parts of the Southeast into the Mid-Atlantic, but weak winds under a broad surface high and marginal fuels should limit wind speeds and the overall fire weather threat. ...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 1021 AM CST Mon Feb 19 2024 Valid 191630Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE SACRAMENTO VALLEY IN CENTRAL INTO NORTHERN CALIFORNIA... ...SUMMARY... A tornado or two may occur in the Sacramento Valley region of California today. ...Synopsis... A pronounced mid-level trough and associated surface low continue to impinge on the West Coast, supporting a continued northward transport of moisture over California into southern portions of the Pacific Northwest. 12Z observed soundings for sites along the California coast already show cooler mid-level temperatures overspreading inland, suggesting that marginal buoyancy should already be present across central into northern CA. With time, insolation will support locally higher amounts of buoyancy amid a highly sheared environment to support low-topped but organized thunderstorms capable of producing severe hazards over portions of central into northern CA this afternoon. ...Portions of central into northern CA... Low-level warm-air advection has encouraged surface temperatures to warm into the mid 50s F across southern portions of the Sacramento Valley prior to diurnal heating. By afternoon, 52-54 F surface dewpoints beneath 7.5+ C/km mid-level lapse rates will boost tall but thin SBCAPE to the 500-750 J/kg range. The BBX VAD currently depicts a sizable, curved low-level hodograph, with over 300 m2/s2 of 0-3 km SRH, and these favorable low-level shear trends are expected to persist through the day as the surface low continues to meander just offshore. Modifying RAP forecast soundings suggest that surface dewpoints need to rise at least into the 53-54F range to support efficient ingesting of SRH for tornadogenesis. It is unclear how widespread 53-54 F dewpoints will become by afternoon, with the tornado threat more conditional on these dewpoints being realized. Nonetheless, a couple of low-topped supercells are possible this afternoon, likely accompanied by at least a marginal severe hail/wind threat. ..Squitieri.. 02/19/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1021 AM CST Mon Feb 19 2024 Valid 191630Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE SACRAMENTO VALLEY IN CENTRAL INTO NORTHERN CALIFORNIA... ...SUMMARY... A tornado or two may occur in the Sacramento Valley region of California today. ...Synopsis... A pronounced mid-level trough and associated surface low continue to impinge on the West Coast, supporting a continued northward transport of moisture over California into southern portions of the Pacific Northwest. 12Z observed soundings for sites along the California coast already show cooler mid-level temperatures overspreading inland, suggesting that marginal buoyancy should already be present across central into northern CA. With time, insolation will support locally higher amounts of buoyancy amid a highly sheared environment to support low-topped but organized thunderstorms capable of producing severe hazards over portions of central into northern CA this afternoon. ...Portions of central into northern CA... Low-level warm-air advection has encouraged surface temperatures to warm into the mid 50s F across southern portions of the Sacramento Valley prior to diurnal heating. By afternoon, 52-54 F surface dewpoints beneath 7.5+ C/km mid-level lapse rates will boost tall but thin SBCAPE to the 500-750 J/kg range. The BBX VAD currently depicts a sizable, curved low-level hodograph, with over 300 m2/s2 of 0-3 km SRH, and these favorable low-level shear trends are expected to persist through the day as the surface low continues to meander just offshore. Modifying RAP forecast soundings suggest that surface dewpoints need to rise at least into the 53-54F range to support efficient ingesting of SRH for tornadogenesis. It is unclear how widespread 53-54 F dewpoints will become by afternoon, with the tornado threat more conditional on these dewpoints being realized. Nonetheless, a couple of low-topped supercells are possible this afternoon, likely accompanied by at least a marginal severe hail/wind threat. ..Squitieri.. 02/19/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1021 AM CST Mon Feb 19 2024 Valid 191630Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE SACRAMENTO VALLEY IN CENTRAL INTO NORTHERN CALIFORNIA... ...SUMMARY... A tornado or two may occur in the Sacramento Valley region of California today. ...Synopsis... A pronounced mid-level trough and associated surface low continue to impinge on the West Coast, supporting a continued northward transport of moisture over California into southern portions of the Pacific Northwest. 12Z observed soundings for sites along the California coast already show cooler mid-level temperatures overspreading inland, suggesting that marginal buoyancy should already be present across central into northern CA. With time, insolation will support locally higher amounts of buoyancy amid a highly sheared environment to support low-topped but organized thunderstorms capable of producing severe hazards over portions of central into northern CA this afternoon. ...Portions of central into northern CA... Low-level warm-air advection has encouraged surface temperatures to warm into the mid 50s F across southern portions of the Sacramento Valley prior to diurnal heating. By afternoon, 52-54 F surface dewpoints beneath 7.5+ C/km mid-level lapse rates will boost tall but thin SBCAPE to the 500-750 J/kg range. The BBX VAD currently depicts a sizable, curved low-level hodograph, with over 300 m2/s2 of 0-3 km SRH, and these favorable low-level shear trends are expected to persist through the day as the surface low continues to meander just offshore. Modifying RAP forecast soundings suggest that surface dewpoints need to rise at least into the 53-54F range to support efficient ingesting of SRH for tornadogenesis. It is unclear how widespread 53-54 F dewpoints will become by afternoon, with the tornado threat more conditional on these dewpoints being realized. Nonetheless, a couple of low-topped supercells are possible this afternoon, likely accompanied by at least a marginal severe hail/wind threat. ..Squitieri.. 02/19/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1021 AM CST Mon Feb 19 2024 Valid 191630Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE SACRAMENTO VALLEY IN CENTRAL INTO NORTHERN CALIFORNIA... ...SUMMARY... A tornado or two may occur in the Sacramento Valley region of California today. ...Synopsis... A pronounced mid-level trough and associated surface low continue to impinge on the West Coast, supporting a continued northward transport of moisture over California into southern portions of the Pacific Northwest. 12Z observed soundings for sites along the California coast already show cooler mid-level temperatures overspreading inland, suggesting that marginal buoyancy should already be present across central into northern CA. With time, insolation will support locally higher amounts of buoyancy amid a highly sheared environment to support low-topped but organized thunderstorms capable of producing severe hazards over portions of central into northern CA this afternoon. ...Portions of central into northern CA... Low-level warm-air advection has encouraged surface temperatures to warm into the mid 50s F across southern portions of the Sacramento Valley prior to diurnal heating. By afternoon, 52-54 F surface dewpoints beneath 7.5+ C/km mid-level lapse rates will boost tall but thin SBCAPE to the 500-750 J/kg range. The BBX VAD currently depicts a sizable, curved low-level hodograph, with over 300 m2/s2 of 0-3 km SRH, and these favorable low-level shear trends are expected to persist through the day as the surface low continues to meander just offshore. Modifying RAP forecast soundings suggest that surface dewpoints need to rise at least into the 53-54F range to support efficient ingesting of SRH for tornadogenesis. It is unclear how widespread 53-54 F dewpoints will become by afternoon, with the tornado threat more conditional on these dewpoints being realized. Nonetheless, a couple of low-topped supercells are possible this afternoon, likely accompanied by at least a marginal severe hail/wind threat. ..Squitieri.. 02/19/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1021 AM CST Mon Feb 19 2024 Valid 191630Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE SACRAMENTO VALLEY IN CENTRAL INTO NORTHERN CALIFORNIA... ...SUMMARY... A tornado or two may occur in the Sacramento Valley region of California today. ...Synopsis... A pronounced mid-level trough and associated surface low continue to impinge on the West Coast, supporting a continued northward transport of moisture over California into southern portions of the Pacific Northwest. 12Z observed soundings for sites along the California coast already show cooler mid-level temperatures overspreading inland, suggesting that marginal buoyancy should already be present across central into northern CA. With time, insolation will support locally higher amounts of buoyancy amid a highly sheared environment to support low-topped but organized thunderstorms capable of producing severe hazards over portions of central into northern CA this afternoon. ...Portions of central into northern CA... Low-level warm-air advection has encouraged surface temperatures to warm into the mid 50s F across southern portions of the Sacramento Valley prior to diurnal heating. By afternoon, 52-54 F surface dewpoints beneath 7.5+ C/km mid-level lapse rates will boost tall but thin SBCAPE to the 500-750 J/kg range. The BBX VAD currently depicts a sizable, curved low-level hodograph, with over 300 m2/s2 of 0-3 km SRH, and these favorable low-level shear trends are expected to persist through the day as the surface low continues to meander just offshore. Modifying RAP forecast soundings suggest that surface dewpoints need to rise at least into the 53-54F range to support efficient ingesting of SRH for tornadogenesis. It is unclear how widespread 53-54 F dewpoints will become by afternoon, with the tornado threat more conditional on these dewpoints being realized. Nonetheless, a couple of low-topped supercells are possible this afternoon, likely accompanied by at least a marginal severe hail/wind threat. ..Squitieri.. 02/19/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1021 AM CST Mon Feb 19 2024 Valid 191630Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE SACRAMENTO VALLEY IN CENTRAL INTO NORTHERN CALIFORNIA... ...SUMMARY... A tornado or two may occur in the Sacramento Valley region of California today. ...Synopsis... A pronounced mid-level trough and associated surface low continue to impinge on the West Coast, supporting a continued northward transport of moisture over California into southern portions of the Pacific Northwest. 12Z observed soundings for sites along the California coast already show cooler mid-level temperatures overspreading inland, suggesting that marginal buoyancy should already be present across central into northern CA. With time, insolation will support locally higher amounts of buoyancy amid a highly sheared environment to support low-topped but organized thunderstorms capable of producing severe hazards over portions of central into northern CA this afternoon. ...Portions of central into northern CA... Low-level warm-air advection has encouraged surface temperatures to warm into the mid 50s F across southern portions of the Sacramento Valley prior to diurnal heating. By afternoon, 52-54 F surface dewpoints beneath 7.5+ C/km mid-level lapse rates will boost tall but thin SBCAPE to the 500-750 J/kg range. The BBX VAD currently depicts a sizable, curved low-level hodograph, with over 300 m2/s2 of 0-3 km SRH, and these favorable low-level shear trends are expected to persist through the day as the surface low continues to meander just offshore. Modifying RAP forecast soundings suggest that surface dewpoints need to rise at least into the 53-54F range to support efficient ingesting of SRH for tornadogenesis. It is unclear how widespread 53-54 F dewpoints will become by afternoon, with the tornado threat more conditional on these dewpoints being realized. Nonetheless, a couple of low-topped supercells are possible this afternoon, likely accompanied by at least a marginal severe hail/wind threat. ..Squitieri.. 02/19/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0648 AM CST Mon Feb 19 2024 Valid 191300Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF INLAND NORTHERN CALIFORNIA.... ...SUMMARY... A tornado or two may occur in the Sacramento Valley region of California today. ...Synopsis... The large-scale pattern will continue to be characterized by a longwave trough just off the West Coast, ridging over the Rockies and High Plains, and a trough over parts of the eastern CONUS and eastern Gulf. Progressive, well-developed shortwave troughs -- now apparent in moisture-channel imagery over GA and the central High Plains -- will move through the broader-scale cyclonic-flow field of the eastern longwave trough. Conditions should remain too stable in low levels to support a thunder threat over land from the Intermountain West eastward to the Atlantic Coast. Upstream, a large cyclone off northern CA and the Pacific Northwest will weaken gradually and shift northward through the period, devolving into an open wave synoptic trough. However, the broader- scale troughing will be maintained, as a strong shortwave perturbation now in the cyclone's northwestern quadrant digs southward then southeastward, approaching 130W west of southern CA and northern Baja by 12Z. These processes will maintain a fetch of southwest flow aloft across CA. A weaker shortwave trough is moving inland over north-central CA, and should cross northwestern NV today before reaching parts of ID around 00Z. ...CA... Scattered showers and isolated to widely scattered thunderstorms are expected this afternoon into early evening. Isolated supercells are possible, with a threat for a tornado or two. Mostly subsevere hail and convective winds are expected, through the largest hail and gusts may briefly reach severe limits. As noted above, the initial shortwave trough is crossing the area, preceded by a precip plume with isolated embedded thunderstorms over the central/northern Sierra and San Joaquin Valley. In the weak subsidence following that perturbation, a few hours of relatively tranquil conditions are expected. Thereafter, upper-level forcing will be nearly neutral, but with diurnal/diabatic heating contributing to low-level destabilization over the Sacramento Valley/Delta region and perhaps northernmost parts of the San Joaquin Valley, beneath favorable low/middle-level lapse rates and weakening of MLCINH. Episodic, isolated to scattered convection and a few thunderstorms are possible again this afternoon into evening, in an environment characterized by favorably veering/increasing winds with height. Orographically forced backing of surface flow in the valley likely will be slightly greater than most models indicate as well, further enlarging already favorable hodographs progged for supercells. Any quasi-linear modes also may contain LEWP/bow features with embedded mesocirculations. Effective SRH of 150-300 J/kg and 40-55-kt effective-shear magnitudes are possible. With surface dewpoints holding generally in the low/mid 50s F, the preconvective/inflow sector may attain 250-700 J/kg peak MLCAPE, based on modifications to the 12Z OAK RAOB and model soundings. A combination of nocturnal surface cooling/stabilization and outflow air should reduce severe potential after dark. Isolated storm-scale rotation also is possible with cells mainly over the Pacific marine layer off the northwestern CA coastline, with waterspout/tornado potential nonzero but too low/conditional over land for an outlook area at this time. ..Edwards/Mosier.. 02/19/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0648 AM CST Mon Feb 19 2024 Valid 191300Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF INLAND NORTHERN CALIFORNIA.... ...SUMMARY... A tornado or two may occur in the Sacramento Valley region of California today. ...Synopsis... The large-scale pattern will continue to be characterized by a longwave trough just off the West Coast, ridging over the Rockies and High Plains, and a trough over parts of the eastern CONUS and eastern Gulf. Progressive, well-developed shortwave troughs -- now apparent in moisture-channel imagery over GA and the central High Plains -- will move through the broader-scale cyclonic-flow field of the eastern longwave trough. Conditions should remain too stable in low levels to support a thunder threat over land from the Intermountain West eastward to the Atlantic Coast. Upstream, a large cyclone off northern CA and the Pacific Northwest will weaken gradually and shift northward through the period, devolving into an open wave synoptic trough. However, the broader- scale troughing will be maintained, as a strong shortwave perturbation now in the cyclone's northwestern quadrant digs southward then southeastward, approaching 130W west of southern CA and northern Baja by 12Z. These processes will maintain a fetch of southwest flow aloft across CA. A weaker shortwave trough is moving inland over north-central CA, and should cross northwestern NV today before reaching parts of ID around 00Z. ...CA... Scattered showers and isolated to widely scattered thunderstorms are expected this afternoon into early evening. Isolated supercells are possible, with a threat for a tornado or two. Mostly subsevere hail and convective winds are expected, through the largest hail and gusts may briefly reach severe limits. As noted above, the initial shortwave trough is crossing the area, preceded by a precip plume with isolated embedded thunderstorms over the central/northern Sierra and San Joaquin Valley. In the weak subsidence following that perturbation, a few hours of relatively tranquil conditions are expected. Thereafter, upper-level forcing will be nearly neutral, but with diurnal/diabatic heating contributing to low-level destabilization over the Sacramento Valley/Delta region and perhaps northernmost parts of the San Joaquin Valley, beneath favorable low/middle-level lapse rates and weakening of MLCINH. Episodic, isolated to scattered convection and a few thunderstorms are possible again this afternoon into evening, in an environment characterized by favorably veering/increasing winds with height. Orographically forced backing of surface flow in the valley likely will be slightly greater than most models indicate as well, further enlarging already favorable hodographs progged for supercells. Any quasi-linear modes also may contain LEWP/bow features with embedded mesocirculations. Effective SRH of 150-300 J/kg and 40-55-kt effective-shear magnitudes are possible. With surface dewpoints holding generally in the low/mid 50s F, the preconvective/inflow sector may attain 250-700 J/kg peak MLCAPE, based on modifications to the 12Z OAK RAOB and model soundings. A combination of nocturnal surface cooling/stabilization and outflow air should reduce severe potential after dark. Isolated storm-scale rotation also is possible with cells mainly over the Pacific marine layer off the northwestern CA coastline, with waterspout/tornado potential nonzero but too low/conditional over land for an outlook area at this time. ..Edwards/Mosier.. 02/19/2024 Read more