Severe Storms

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1253 AM CST Tue Feb 20 2024 Valid 211200Z - 221200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR SOUTHEAST KANSAS AND SOUTHWEST MISSOURI... ...SUMMARY... Isolated thunderstorms potentially capable of severe hail are possible late night Wednesday over mainly southeast Kansas and southwest Missouri. ...Southeast KS into the Ozarks... Models exhibit good agreement in showing a quick-moving mid-level speed max initially near northern Baja California moving into OK/AR by early Thursday morning. As the disturbance translates eastward, a surface low will develop near the OK Panhandle and parallel the KS/OK border overnight. Southerly low-level flow intensifying with the onset of a LLJ Wednesday evening will yield strong large-scale ascent focused over southern KS east into the Ozarks. Isolated to widely scattered thunderstorms are forecast to develop primarily after 06z over southern KS. A strong capping inversion located over OK/TX will likely inhibit storm development to be near the surface wave. Cold temperatures in the midlevels (-20 to -22 deg C at 500 mb) with models showing dewpoints near 50 deg F will likely yield 500-1000 J/kg MUCAPE. Marginally severe hail will be possible with the stronger elevated storms as they migrate east overnight. ..Smith.. 02/20/2024 Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1253 AM CST Tue Feb 20 2024 Valid 211200Z - 221200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR SOUTHEAST KANSAS AND SOUTHWEST MISSOURI... ...SUMMARY... Isolated thunderstorms potentially capable of severe hail are possible late night Wednesday over mainly southeast Kansas and southwest Missouri. ...Southeast KS into the Ozarks... Models exhibit good agreement in showing a quick-moving mid-level speed max initially near northern Baja California moving into OK/AR by early Thursday morning. As the disturbance translates eastward, a surface low will develop near the OK Panhandle and parallel the KS/OK border overnight. Southerly low-level flow intensifying with the onset of a LLJ Wednesday evening will yield strong large-scale ascent focused over southern KS east into the Ozarks. Isolated to widely scattered thunderstorms are forecast to develop primarily after 06z over southern KS. A strong capping inversion located over OK/TX will likely inhibit storm development to be near the surface wave. Cold temperatures in the midlevels (-20 to -22 deg C at 500 mb) with models showing dewpoints near 50 deg F will likely yield 500-1000 J/kg MUCAPE. Marginally severe hail will be possible with the stronger elevated storms as they migrate east overnight. ..Smith.. 02/20/2024 Read more

SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1253 AM CST Tue Feb 20 2024 Valid 211200Z - 221200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR SOUTHEAST KANSAS AND SOUTHWEST MISSOURI... ...SUMMARY... Isolated thunderstorms potentially capable of severe hail are possible late night Wednesday over mainly southeast Kansas and southwest Missouri. ...Southeast KS into the Ozarks... Models exhibit good agreement in showing a quick-moving mid-level speed max initially near northern Baja California moving into OK/AR by early Thursday morning. As the disturbance translates eastward, a surface low will develop near the OK Panhandle and parallel the KS/OK border overnight. Southerly low-level flow intensifying with the onset of a LLJ Wednesday evening will yield strong large-scale ascent focused over southern KS east into the Ozarks. Isolated to widely scattered thunderstorms are forecast to develop primarily after 06z over southern KS. A strong capping inversion located over OK/TX will likely inhibit storm development to be near the surface wave. Cold temperatures in the midlevels (-20 to -22 deg C at 500 mb) with models showing dewpoints near 50 deg F will likely yield 500-1000 J/kg MUCAPE. Marginally severe hail will be possible with the stronger elevated storms as they migrate east overnight. ..Smith.. 02/20/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1152 PM 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. ...Synopsis... Thunderstorm potential over the CONUS will remain focused across the Western states for today/tonight. 05 UTC water-vapor imagery reveals an upper trough just off the West Coast with two more prominent vorticity maxima evident off the OR and southern CA coasts. The occluding northern cyclone is forecast to weaken and migrate north as the southern shortwave drifts east towards SoCAL within a belt of stronger mid/upper-level flow. Cool mid-level temperatures were sampled by 00 UTC soundings at OAK and VGB with colder temperatures likely offshore closer to the main trough axis based on satellite imagery and upper-air analyses. These cool mid-level temperatures will gradually spread east through the day and should promote marginal, but adequate, buoyancy for convection amid modest diurnal warming. As with yesterday/Monday, isolated to scattered shallow convection is anticipated; however, unlike Monday, kinematic fields co-located with surface-based buoyancy are expected to be modest given the overall weakening of the synoptic wave. Consequently, the potential for organized convection should be lower, negating the need for risk probabilities. ..Moore.. 02/20/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1152 PM 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. ...Synopsis... Thunderstorm potential over the CONUS will remain focused across the Western states for today/tonight. 05 UTC water-vapor imagery reveals an upper trough just off the West Coast with two more prominent vorticity maxima evident off the OR and southern CA coasts. The occluding northern cyclone is forecast to weaken and migrate north as the southern shortwave drifts east towards SoCAL within a belt of stronger mid/upper-level flow. Cool mid-level temperatures were sampled by 00 UTC soundings at OAK and VGB with colder temperatures likely offshore closer to the main trough axis based on satellite imagery and upper-air analyses. These cool mid-level temperatures will gradually spread east through the day and should promote marginal, but adequate, buoyancy for convection amid modest diurnal warming. As with yesterday/Monday, isolated to scattered shallow convection is anticipated; however, unlike Monday, kinematic fields co-located with surface-based buoyancy are expected to be modest given the overall weakening of the synoptic wave. Consequently, the potential for organized convection should be lower, negating the need for risk probabilities. ..Moore.. 02/20/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1152 PM 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. ...Synopsis... Thunderstorm potential over the CONUS will remain focused across the Western states for today/tonight. 05 UTC water-vapor imagery reveals an upper trough just off the West Coast with two more prominent vorticity maxima evident off the OR and southern CA coasts. The occluding northern cyclone is forecast to weaken and migrate north as the southern shortwave drifts east towards SoCAL within a belt of stronger mid/upper-level flow. Cool mid-level temperatures were sampled by 00 UTC soundings at OAK and VGB with colder temperatures likely offshore closer to the main trough axis based on satellite imagery and upper-air analyses. These cool mid-level temperatures will gradually spread east through the day and should promote marginal, but adequate, buoyancy for convection amid modest diurnal warming. As with yesterday/Monday, isolated to scattered shallow convection is anticipated; however, unlike Monday, kinematic fields co-located with surface-based buoyancy are expected to be modest given the overall weakening of the synoptic wave. Consequently, the potential for organized convection should be lower, negating the need for risk probabilities. ..Moore.. 02/20/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1152 PM 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. ...Synopsis... Thunderstorm potential over the CONUS will remain focused across the Western states for today/tonight. 05 UTC water-vapor imagery reveals an upper trough just off the West Coast with two more prominent vorticity maxima evident off the OR and southern CA coasts. The occluding northern cyclone is forecast to weaken and migrate north as the southern shortwave drifts east towards SoCAL within a belt of stronger mid/upper-level flow. Cool mid-level temperatures were sampled by 00 UTC soundings at OAK and VGB with colder temperatures likely offshore closer to the main trough axis based on satellite imagery and upper-air analyses. These cool mid-level temperatures will gradually spread east through the day and should promote marginal, but adequate, buoyancy for convection amid modest diurnal warming. As with yesterday/Monday, isolated to scattered shallow convection is anticipated; however, unlike Monday, kinematic fields co-located with surface-based buoyancy are expected to be modest given the overall weakening of the synoptic wave. Consequently, the potential for organized convection should be lower, negating the need for risk probabilities. ..Moore.. 02/20/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1152 PM 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. ...Synopsis... Thunderstorm potential over the CONUS will remain focused across the Western states for today/tonight. 05 UTC water-vapor imagery reveals an upper trough just off the West Coast with two more prominent vorticity maxima evident off the OR and southern CA coasts. The occluding northern cyclone is forecast to weaken and migrate north as the southern shortwave drifts east towards SoCAL within a belt of stronger mid/upper-level flow. Cool mid-level temperatures were sampled by 00 UTC soundings at OAK and VGB with colder temperatures likely offshore closer to the main trough axis based on satellite imagery and upper-air analyses. These cool mid-level temperatures will gradually spread east through the day and should promote marginal, but adequate, buoyancy for convection amid modest diurnal warming. As with yesterday/Monday, isolated to scattered shallow convection is anticipated; however, unlike Monday, kinematic fields co-located with surface-based buoyancy are expected to be modest given the overall weakening of the synoptic wave. Consequently, the potential for organized convection should be lower, negating the need for risk probabilities. ..Moore.. 02/20/2024 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0650 PM CST Mon Feb 19 2024 Valid 200100Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE SACRAMENTO VALLEY IN NORTHERN CALIFORNIA... ...SUMMARY... A couple of strong storms may impact parts of the Sacramento Valley through the evening hours, and perhaps pose at least some risk for producing a tornado or two. ...Synopsis... Over the past 1-2 hours, several weak, low-topped supercells have been observed along the central CA coast and within the northern Sacramento Valley. The duration and overall intensity of these storms has been limited, but organized mid-level mesocyclones noted in regional velocity data suggest the kinematic environment remains supportive of at least a low-end tornado threat in the near-term (next 1-2 hours). However, this threat is expected to gradually diminish through late evening and overnight hours. Recent RAP/HRRR runs appear to be initializing too warm/moist at the surface based on recent observations and the 00 UTC OAK sounding, resulting in a slight over-estimation of environmental buoyancy. This consideration, combined with the expectation of diminishing SBCAPE with the onset of nocturnal cooling, suggests that the thermodynamic environment will become increasingly prohibitive of robust convection heading into the overnight hours. Furthermore, surface winds are beginning to back across the western half of the Sacramento Valley, which should lead to diminishing low-level shear across portions of the effective warm sector. For this reason, the 5% tornado probabilities have been removed, though a low-end severe threat will persist given potential for additional shallow/weak supercells. ..Moore.. 02/20/2024 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0650 PM CST Mon Feb 19 2024 Valid 200100Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE SACRAMENTO VALLEY IN NORTHERN CALIFORNIA... ...SUMMARY... A couple of strong storms may impact parts of the Sacramento Valley through the evening hours, and perhaps pose at least some risk for producing a tornado or two. ...Synopsis... Over the past 1-2 hours, several weak, low-topped supercells have been observed along the central CA coast and within the northern Sacramento Valley. The duration and overall intensity of these storms has been limited, but organized mid-level mesocyclones noted in regional velocity data suggest the kinematic environment remains supportive of at least a low-end tornado threat in the near-term (next 1-2 hours). However, this threat is expected to gradually diminish through late evening and overnight hours. Recent RAP/HRRR runs appear to be initializing too warm/moist at the surface based on recent observations and the 00 UTC OAK sounding, resulting in a slight over-estimation of environmental buoyancy. This consideration, combined with the expectation of diminishing SBCAPE with the onset of nocturnal cooling, suggests that the thermodynamic environment will become increasingly prohibitive of robust convection heading into the overnight hours. Furthermore, surface winds are beginning to back across the western half of the Sacramento Valley, which should lead to diminishing low-level shear across portions of the effective warm sector. For this reason, the 5% tornado probabilities have been removed, though a low-end severe threat will persist given potential for additional shallow/weak supercells. ..Moore.. 02/20/2024 Read more

No watches are valid as of Mon Feb 19 23:16:02 UTC 2024.

No Mesoscale Discussions are in effect as of Mon Feb 19 23:16:02 UTC 2024.

MD 0154 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF CENTRAL INTO NORTHERN CALIFORNIA
Mesoscale Discussion 0154 NWS Storm Prediction Center Norman OK 0251 PM CST Mon Feb 19 2024 Areas affected...portions of central into northern California Concerning...Severe potential...Watch unlikely Valid 192051Z - 192315Z Probability of Watch Issuance...20 percent SUMMARY...A couple of semi-discrete, low-topped supercells may form later this afternoon, accompanied by a brief tornado or marginally severe hail/wind risk. A WW issuance appears unlikely given the brief, localized nature of the severe threat. DISCUSSION...A pronounced mid-level trough and associated surface low continue to promote strong flow fields over central into northern CA as they linger just offshore. Some clearing of clouds and precipitation over portions of the Sacramento Valley have allowed surface temperatures to reach the lower to mid 60s F in spots. While 7 C/km mid-level lapse rates (per 20Z mesoanalysis) overspread the low to mid 60s F temperatures, the diurnal heating has also allowed for the mixing of the low-level moisture, with surface dewpoints only as high as 50 F in spots. These lower dewpoints support thin SBCAPE profiles (no more than 500 J/kg in most spots). While the DAX and BBX VADs show relatively large, curved hodographs (300+ m2/s2 0-3 km SRH), RAP forecast soundings suggest that such low dewpoints do not sufficiently destabilize the boundary layer for optimal ingestion of the available SRH. While low-topped storms (perhaps supercells) may develop later today with a marginally severe hail/wind threat, the tornado risk is a bit more uncertain. Nonetheless, if a robust, discrete low-topped supercell manages to develop, a brief tornado cannot be ruled out. Coverage of robust updrafts over the Sacramento Valley remains uncertain, and any severe threat that can materialize should be brief and very localized. As such, a WW issuance does not appear likely at this time. ..Squitieri/Hart.. 02/19/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...STO... LAT...LON 37722118 38152156 38642204 39472230 39902239 40122223 40132198 39742164 39032119 38592095 38092066 37822069 37692082 37622090 37722118 Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0356 PM CST Mon Feb 19 2024 Valid 211200Z - 271200Z Periods of dry and windy conditions will be possible through the extended period D3/Wednesday through D4/Thursday and potentially D8/Monday, with some drying of fuels anticipated across the southern High Plains (especially on D3/Wednesday). On D3/Wednesday, the Pacific trough will move inland across the western US, with enhanced flow aloft overspreading the southern Rockies. As a result, lee cyclogenesis will favor strong westerly surface winds and low RH across the southern High Plains. Recent fuel analysis indicates that fuels across eastern New Mexico will support inclusion of 40 percent probabilities on Wednesday where afternoon relative humidity reductions to 15-20 percent will overlap sustained winds 20-30 mph. Fuels remain around the 50th percentile but as further drying occurs are expected to support some risk of increased fire potential. Dry and windy conditions will extend into the Texas Panhandle, southwest Texas, and far eastern Texas. Fuels within this region have received more recent rain and snowfall and remain less receptive to fire spread. Poor recovery is likely overnight D3/Wednesday - D4/Thursday across southwestern and far western Texas, with breezy post frontal northwesterly flow overlapping elevated to critical relative humidity again Thursday afternoon. The best overlap of windy/dry conditions will overlap unreceptive fuels across southwest Texas precluding the need for probabilities at this time. An upper-level ridge will build in across the western US with downstream troughing across the east D4-Friday through D7-Sunday. Surface high pressure across the central US will keep winds generally light where the driest conditions are expected in the central and southern high Plains. Late D7/Sunday into D8/Monday an upper-level low will begin to phase with the Polar jet stream and move eastward, with a belt of enhanced westerly flow aloft overspreading the Rockies and potential for lee trough development. This pattern will favor a return of windy/dry westerly downslope flow into the central/southern Plains. ..Thornton.. 02/19/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0356 PM CST Mon Feb 19 2024 Valid 211200Z - 271200Z Periods of dry and windy conditions will be possible through the extended period D3/Wednesday through D4/Thursday and potentially D8/Monday, with some drying of fuels anticipated across the southern High Plains (especially on D3/Wednesday). On D3/Wednesday, the Pacific trough will move inland across the western US, with enhanced flow aloft overspreading the southern Rockies. As a result, lee cyclogenesis will favor strong westerly surface winds and low RH across the southern High Plains. Recent fuel analysis indicates that fuels across eastern New Mexico will support inclusion of 40 percent probabilities on Wednesday where afternoon relative humidity reductions to 15-20 percent will overlap sustained winds 20-30 mph. Fuels remain around the 50th percentile but as further drying occurs are expected to support some risk of increased fire potential. Dry and windy conditions will extend into the Texas Panhandle, southwest Texas, and far eastern Texas. Fuels within this region have received more recent rain and snowfall and remain less receptive to fire spread. Poor recovery is likely overnight D3/Wednesday - D4/Thursday across southwestern and far western Texas, with breezy post frontal northwesterly flow overlapping elevated to critical relative humidity again Thursday afternoon. The best overlap of windy/dry conditions will overlap unreceptive fuels across southwest Texas precluding the need for probabilities at this time. An upper-level ridge will build in across the western US with downstream troughing across the east D4-Friday through D7-Sunday. Surface high pressure across the central US will keep winds generally light where the driest conditions are expected in the central and southern high Plains. Late D7/Sunday into D8/Monday an upper-level low will begin to phase with the Polar jet stream and move eastward, with a belt of enhanced westerly flow aloft overspreading the Rockies and potential for lee trough development. This pattern will favor a return of windy/dry westerly downslope flow into the central/southern Plains. ..Thornton.. 02/19/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0356 PM CST Mon Feb 19 2024 Valid 211200Z - 271200Z Periods of dry and windy conditions will be possible through the extended period D3/Wednesday through D4/Thursday and potentially D8/Monday, with some drying of fuels anticipated across the southern High Plains (especially on D3/Wednesday). On D3/Wednesday, the Pacific trough will move inland across the western US, with enhanced flow aloft overspreading the southern Rockies. As a result, lee cyclogenesis will favor strong westerly surface winds and low RH across the southern High Plains. Recent fuel analysis indicates that fuels across eastern New Mexico will support inclusion of 40 percent probabilities on Wednesday where afternoon relative humidity reductions to 15-20 percent will overlap sustained winds 20-30 mph. Fuels remain around the 50th percentile but as further drying occurs are expected to support some risk of increased fire potential. Dry and windy conditions will extend into the Texas Panhandle, southwest Texas, and far eastern Texas. Fuels within this region have received more recent rain and snowfall and remain less receptive to fire spread. Poor recovery is likely overnight D3/Wednesday - D4/Thursday across southwestern and far western Texas, with breezy post frontal northwesterly flow overlapping elevated to critical relative humidity again Thursday afternoon. The best overlap of windy/dry conditions will overlap unreceptive fuels across southwest Texas precluding the need for probabilities at this time. An upper-level ridge will build in across the western US with downstream troughing across the east D4-Friday through D7-Sunday. Surface high pressure across the central US will keep winds generally light where the driest conditions are expected in the central and southern high Plains. Late D7/Sunday into D8/Monday an upper-level low will begin to phase with the Polar jet stream and move eastward, with a belt of enhanced westerly flow aloft overspreading the Rockies and potential for lee trough development. This pattern will favor a return of windy/dry westerly downslope flow into the central/southern Plains. ..Thornton.. 02/19/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0356 PM CST Mon Feb 19 2024 Valid 211200Z - 271200Z Periods of dry and windy conditions will be possible through the extended period D3/Wednesday through D4/Thursday and potentially D8/Monday, with some drying of fuels anticipated across the southern High Plains (especially on D3/Wednesday). On D3/Wednesday, the Pacific trough will move inland across the western US, with enhanced flow aloft overspreading the southern Rockies. As a result, lee cyclogenesis will favor strong westerly surface winds and low RH across the southern High Plains. Recent fuel analysis indicates that fuels across eastern New Mexico will support inclusion of 40 percent probabilities on Wednesday where afternoon relative humidity reductions to 15-20 percent will overlap sustained winds 20-30 mph. Fuels remain around the 50th percentile but as further drying occurs are expected to support some risk of increased fire potential. Dry and windy conditions will extend into the Texas Panhandle, southwest Texas, and far eastern Texas. Fuels within this region have received more recent rain and snowfall and remain less receptive to fire spread. Poor recovery is likely overnight D3/Wednesday - D4/Thursday across southwestern and far western Texas, with breezy post frontal northwesterly flow overlapping elevated to critical relative humidity again Thursday afternoon. The best overlap of windy/dry conditions will overlap unreceptive fuels across southwest Texas precluding the need for probabilities at this time. An upper-level ridge will build in across the western US with downstream troughing across the east D4-Friday through D7-Sunday. Surface high pressure across the central US will keep winds generally light where the driest conditions are expected in the central and southern high Plains. Late D7/Sunday into D8/Monday an upper-level low will begin to phase with the Polar jet stream and move eastward, with a belt of enhanced westerly flow aloft overspreading the Rockies and potential for lee trough development. This pattern will favor a return of windy/dry westerly downslope flow into the central/southern Plains. ..Thornton.. 02/19/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0149 PM CST Mon Feb 19 2024 Valid 192000Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO EVENING ACROSS INTERIOR NORTHERN CALIFORNIA... ...SUMMARY... A couple of strong storms may impact parts of the Sacramento Valley by late this afternoon, and perhaps pose at least some risk for producing a tornado or two. ...20Z Update... There has been some adjustment to the outlook, mainly to account for the progression of the synoptic/sub-synoptic features and ongoing trends concerning instability. The occluding offshore cyclone (roughly centered near or northeast of 40N/130W at 19Z) is in the process of gradually weakening. Stronger mid-level height falls are also weakening, and spreading northeast/east of the southern Cascades and northern Sierra Nevada. However, flow appears to remain moderately strong and southerly (near or above 40 kt) around 850 mb across much of the Sacramento Valley, and this is contributing sizable clockwise-curved low-level hodographs, as insolation contributes to at least weak boundary-layer destabilization beneath modestly cold mid-level temperatures. It is not clear that forcing for ascent will support more than one or two boundary-layer based storms over the Sacramento Valley late this afternoon and evening, but the environment still appears conditionally conducive to a low-topped supercell with the potential to produce a brief tornado or two. ..Kerr.. 02/19/2024 .PREV DISCUSSION... /ISSUED 1021 AM CST Mon Feb 19 2024/ ...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. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0149 PM CST Mon Feb 19 2024 Valid 192000Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO EVENING ACROSS INTERIOR NORTHERN CALIFORNIA... ...SUMMARY... A couple of strong storms may impact parts of the Sacramento Valley by late this afternoon, and perhaps pose at least some risk for producing a tornado or two. ...20Z Update... There has been some adjustment to the outlook, mainly to account for the progression of the synoptic/sub-synoptic features and ongoing trends concerning instability. The occluding offshore cyclone (roughly centered near or northeast of 40N/130W at 19Z) is in the process of gradually weakening. Stronger mid-level height falls are also weakening, and spreading northeast/east of the southern Cascades and northern Sierra Nevada. However, flow appears to remain moderately strong and southerly (near or above 40 kt) around 850 mb across much of the Sacramento Valley, and this is contributing sizable clockwise-curved low-level hodographs, as insolation contributes to at least weak boundary-layer destabilization beneath modestly cold mid-level temperatures. It is not clear that forcing for ascent will support more than one or two boundary-layer based storms over the Sacramento Valley late this afternoon and evening, but the environment still appears conditionally conducive to a low-topped supercell with the potential to produce a brief tornado or two. ..Kerr.. 02/19/2024 .PREV DISCUSSION... /ISSUED 1021 AM CST Mon Feb 19 2024/ ...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. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0149 PM CST Mon Feb 19 2024 Valid 192000Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO EVENING ACROSS INTERIOR NORTHERN CALIFORNIA... ...SUMMARY... A couple of strong storms may impact parts of the Sacramento Valley by late this afternoon, and perhaps pose at least some risk for producing a tornado or two. ...20Z Update... There has been some adjustment to the outlook, mainly to account for the progression of the synoptic/sub-synoptic features and ongoing trends concerning instability. The occluding offshore cyclone (roughly centered near or northeast of 40N/130W at 19Z) is in the process of gradually weakening. Stronger mid-level height falls are also weakening, and spreading northeast/east of the southern Cascades and northern Sierra Nevada. However, flow appears to remain moderately strong and southerly (near or above 40 kt) around 850 mb across much of the Sacramento Valley, and this is contributing sizable clockwise-curved low-level hodographs, as insolation contributes to at least weak boundary-layer destabilization beneath modestly cold mid-level temperatures. It is not clear that forcing for ascent will support more than one or two boundary-layer based storms over the Sacramento Valley late this afternoon and evening, but the environment still appears conditionally conducive to a low-topped supercell with the potential to produce a brief tornado or two. ..Kerr.. 02/19/2024 .PREV DISCUSSION... /ISSUED 1021 AM CST Mon Feb 19 2024/ ...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. Read more