Severe Storms

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1125 AM CST Thu Jan 18 2024 Valid 191200Z - 201200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms are not expected on Friday. ...Synopsis... A large-scale mid-level trough will reside over the Eastern US and get reinforced by a disturbance moving from the Upper Midwest into the OH Valley. Farther west, a mid-level ridge over the Intermountain West will slowly shift east to the Rockies as a mid-level low/trough approaches the CA coast. In the low levels, a cold front of arctic origin will quickly push south/southeast from the northern Gulf of Mexico through the FL Peninsula during the day. A non-zero thunderstorm chance may extend from the shelf waters of the FL Keys into south FL, and in a separate area of coastal CA near San Francisco Bay. Surface high pressure will be pervasive over much of the Lower 48 states. ..Smith.. 01/18/2024 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1032 AM CST Thu Jan 18 2024 Valid 181700Z - 191200Z ...NO CRITICAL AREAS... The previous forecast (see below) remains on track, with no changes or additions made. ..Squitieri.. 01/18/2024 .PREV DISCUSSION... /ISSUED 1001 PM CST Wed Jan 17 2024/ ...Synopsis... A low-amplitude shortwave trough accompanied by a robust northwesterly jet streak will cross the northern/central Rockies, favoring the southward evolution of a weak lee cyclone over the central High Plains -- immediately ahead of a southward-surging cold front. A modest pressure gradient along the southern periphery of the lee cyclone will support 15-20 mph sustained westerly surface winds (with higher gusts) across the southern High Plains. Downslope warming/drying should contribute to around 20 percent minimum RH over the TX Trans-Pecos, where locally elevated fire-weather conditions are possible. However, marginal fuels across the area should limit fire-weather potential. ...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 1032 AM CST Thu Jan 18 2024 Valid 181700Z - 191200Z ...NO CRITICAL AREAS... The previous forecast (see below) remains on track, with no changes or additions made. ..Squitieri.. 01/18/2024 .PREV DISCUSSION... /ISSUED 1001 PM CST Wed Jan 17 2024/ ...Synopsis... A low-amplitude shortwave trough accompanied by a robust northwesterly jet streak will cross the northern/central Rockies, favoring the southward evolution of a weak lee cyclone over the central High Plains -- immediately ahead of a southward-surging cold front. A modest pressure gradient along the southern periphery of the lee cyclone will support 15-20 mph sustained westerly surface winds (with higher gusts) across the southern High Plains. Downslope warming/drying should contribute to around 20 percent minimum RH over the TX Trans-Pecos, where locally elevated fire-weather conditions are possible. However, marginal fuels across the area should limit fire-weather potential. ...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 1032 AM CST Thu Jan 18 2024 Valid 181700Z - 191200Z ...NO CRITICAL AREAS... The previous forecast (see below) remains on track, with no changes or additions made. ..Squitieri.. 01/18/2024 .PREV DISCUSSION... /ISSUED 1001 PM CST Wed Jan 17 2024/ ...Synopsis... A low-amplitude shortwave trough accompanied by a robust northwesterly jet streak will cross the northern/central Rockies, favoring the southward evolution of a weak lee cyclone over the central High Plains -- immediately ahead of a southward-surging cold front. A modest pressure gradient along the southern periphery of the lee cyclone will support 15-20 mph sustained westerly surface winds (with higher gusts) across the southern High Plains. Downslope warming/drying should contribute to around 20 percent minimum RH over the TX Trans-Pecos, where locally elevated fire-weather conditions are possible. However, marginal fuels across the area should limit fire-weather potential. ...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 1032 AM CST Thu Jan 18 2024 Valid 181700Z - 191200Z ...NO CRITICAL AREAS... The previous forecast (see below) remains on track, with no changes or additions made. ..Squitieri.. 01/18/2024 .PREV DISCUSSION... /ISSUED 1001 PM CST Wed Jan 17 2024/ ...Synopsis... A low-amplitude shortwave trough accompanied by a robust northwesterly jet streak will cross the northern/central Rockies, favoring the southward evolution of a weak lee cyclone over the central High Plains -- immediately ahead of a southward-surging cold front. A modest pressure gradient along the southern periphery of the lee cyclone will support 15-20 mph sustained westerly surface winds (with higher gusts) across the southern High Plains. Downslope warming/drying should contribute to around 20 percent minimum RH over the TX Trans-Pecos, where locally elevated fire-weather conditions are possible. However, marginal fuels across the area should limit fire-weather potential. ...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 1032 AM CST Thu Jan 18 2024 Valid 181700Z - 191200Z ...NO CRITICAL AREAS... The previous forecast (see below) remains on track, with no changes or additions made. ..Squitieri.. 01/18/2024 .PREV DISCUSSION... /ISSUED 1001 PM CST Wed Jan 17 2024/ ...Synopsis... A low-amplitude shortwave trough accompanied by a robust northwesterly jet streak will cross the northern/central Rockies, favoring the southward evolution of a weak lee cyclone over the central High Plains -- immediately ahead of a southward-surging cold front. A modest pressure gradient along the southern periphery of the lee cyclone will support 15-20 mph sustained westerly surface winds (with higher gusts) across the southern High Plains. Downslope warming/drying should contribute to around 20 percent minimum RH over the TX Trans-Pecos, where locally elevated fire-weather conditions are possible. However, marginal fuels across the area should limit fire-weather potential. ...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 1032 AM CST Thu Jan 18 2024 Valid 181700Z - 191200Z ...NO CRITICAL AREAS... The previous forecast (see below) remains on track, with no changes or additions made. ..Squitieri.. 01/18/2024 .PREV DISCUSSION... /ISSUED 1001 PM CST Wed Jan 17 2024/ ...Synopsis... A low-amplitude shortwave trough accompanied by a robust northwesterly jet streak will cross the northern/central Rockies, favoring the southward evolution of a weak lee cyclone over the central High Plains -- immediately ahead of a southward-surging cold front. A modest pressure gradient along the southern periphery of the lee cyclone will support 15-20 mph sustained westerly surface winds (with higher gusts) across the southern High Plains. Downslope warming/drying should contribute to around 20 percent minimum RH over the TX Trans-Pecos, where locally elevated fire-weather conditions are possible. However, marginal fuels across the area should limit fire-weather potential. ...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 1016 AM CST Thu Jan 18 2024 Valid 181630Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... A few thunderstorms may develop across parts of south Florida today into tonight. ...Synopsis... Thunderstorm potential is expected to remain limited to southern Florida, and perhaps the northern Gulf, for today and tonight. Cool continental air remains in place across the majority of the country with any appreciable moisture confined to the southern FL peninsula in the vicinity of diffuse warm frontal zone. Weak ascent associated with modest low-level warm air advection and lift within the right-entrance region of an exiting upper-level jet should support isolated thunderstorm development later this afternoon into the early evening. While low-level wind profiles should remain meager, 40-50 knot flow aloft may support transient storm organization, though weak forcing for ascent should preclude a more robust severe thunderstorm threat. To the northwest, broad cyclonic flow aloft over the central Plains/Midwest is expected to amplify over the next 24 hours as a surge of continental air pushes south. Embedded disturbances within the mean cyclonic flow regime will propagate from the central/high Plains towards the Southeast through tonight. Shallow convective showers should develop over the northern Gulf and into coastal LA/MS/AL within a modest warm advection regime ahead of one of these disturbances. A few lightning flashes are possible, but poor mid-level lapse rates and limited ascent should keep thunderstorm coverage below 10%. ..Moore.. 01/18/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1016 AM CST Thu Jan 18 2024 Valid 181630Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... A few thunderstorms may develop across parts of south Florida today into tonight. ...Synopsis... Thunderstorm potential is expected to remain limited to southern Florida, and perhaps the northern Gulf, for today and tonight. Cool continental air remains in place across the majority of the country with any appreciable moisture confined to the southern FL peninsula in the vicinity of diffuse warm frontal zone. Weak ascent associated with modest low-level warm air advection and lift within the right-entrance region of an exiting upper-level jet should support isolated thunderstorm development later this afternoon into the early evening. While low-level wind profiles should remain meager, 40-50 knot flow aloft may support transient storm organization, though weak forcing for ascent should preclude a more robust severe thunderstorm threat. To the northwest, broad cyclonic flow aloft over the central Plains/Midwest is expected to amplify over the next 24 hours as a surge of continental air pushes south. Embedded disturbances within the mean cyclonic flow regime will propagate from the central/high Plains towards the Southeast through tonight. Shallow convective showers should develop over the northern Gulf and into coastal LA/MS/AL within a modest warm advection regime ahead of one of these disturbances. A few lightning flashes are possible, but poor mid-level lapse rates and limited ascent should keep thunderstorm coverage below 10%. ..Moore.. 01/18/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1016 AM CST Thu Jan 18 2024 Valid 181630Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... A few thunderstorms may develop across parts of south Florida today into tonight. ...Synopsis... Thunderstorm potential is expected to remain limited to southern Florida, and perhaps the northern Gulf, for today and tonight. Cool continental air remains in place across the majority of the country with any appreciable moisture confined to the southern FL peninsula in the vicinity of diffuse warm frontal zone. Weak ascent associated with modest low-level warm air advection and lift within the right-entrance region of an exiting upper-level jet should support isolated thunderstorm development later this afternoon into the early evening. While low-level wind profiles should remain meager, 40-50 knot flow aloft may support transient storm organization, though weak forcing for ascent should preclude a more robust severe thunderstorm threat. To the northwest, broad cyclonic flow aloft over the central Plains/Midwest is expected to amplify over the next 24 hours as a surge of continental air pushes south. Embedded disturbances within the mean cyclonic flow regime will propagate from the central/high Plains towards the Southeast through tonight. Shallow convective showers should develop over the northern Gulf and into coastal LA/MS/AL within a modest warm advection regime ahead of one of these disturbances. A few lightning flashes are possible, but poor mid-level lapse rates and limited ascent should keep thunderstorm coverage below 10%. ..Moore.. 01/18/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1016 AM CST Thu Jan 18 2024 Valid 181630Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... A few thunderstorms may develop across parts of south Florida today into tonight. ...Synopsis... Thunderstorm potential is expected to remain limited to southern Florida, and perhaps the northern Gulf, for today and tonight. Cool continental air remains in place across the majority of the country with any appreciable moisture confined to the southern FL peninsula in the vicinity of diffuse warm frontal zone. Weak ascent associated with modest low-level warm air advection and lift within the right-entrance region of an exiting upper-level jet should support isolated thunderstorm development later this afternoon into the early evening. While low-level wind profiles should remain meager, 40-50 knot flow aloft may support transient storm organization, though weak forcing for ascent should preclude a more robust severe thunderstorm threat. To the northwest, broad cyclonic flow aloft over the central Plains/Midwest is expected to amplify over the next 24 hours as a surge of continental air pushes south. Embedded disturbances within the mean cyclonic flow regime will propagate from the central/high Plains towards the Southeast through tonight. Shallow convective showers should develop over the northern Gulf and into coastal LA/MS/AL within a modest warm advection regime ahead of one of these disturbances. A few lightning flashes are possible, but poor mid-level lapse rates and limited ascent should keep thunderstorm coverage below 10%. ..Moore.. 01/18/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1016 AM CST Thu Jan 18 2024 Valid 181630Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... A few thunderstorms may develop across parts of south Florida today into tonight. ...Synopsis... Thunderstorm potential is expected to remain limited to southern Florida, and perhaps the northern Gulf, for today and tonight. Cool continental air remains in place across the majority of the country with any appreciable moisture confined to the southern FL peninsula in the vicinity of diffuse warm frontal zone. Weak ascent associated with modest low-level warm air advection and lift within the right-entrance region of an exiting upper-level jet should support isolated thunderstorm development later this afternoon into the early evening. While low-level wind profiles should remain meager, 40-50 knot flow aloft may support transient storm organization, though weak forcing for ascent should preclude a more robust severe thunderstorm threat. To the northwest, broad cyclonic flow aloft over the central Plains/Midwest is expected to amplify over the next 24 hours as a surge of continental air pushes south. Embedded disturbances within the mean cyclonic flow regime will propagate from the central/high Plains towards the Southeast through tonight. Shallow convective showers should develop over the northern Gulf and into coastal LA/MS/AL within a modest warm advection regime ahead of one of these disturbances. A few lightning flashes are possible, but poor mid-level lapse rates and limited ascent should keep thunderstorm coverage below 10%. ..Moore.. 01/18/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1016 AM CST Thu Jan 18 2024 Valid 181630Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... A few thunderstorms may develop across parts of south Florida today into tonight. ...Synopsis... Thunderstorm potential is expected to remain limited to southern Florida, and perhaps the northern Gulf, for today and tonight. Cool continental air remains in place across the majority of the country with any appreciable moisture confined to the southern FL peninsula in the vicinity of diffuse warm frontal zone. Weak ascent associated with modest low-level warm air advection and lift within the right-entrance region of an exiting upper-level jet should support isolated thunderstorm development later this afternoon into the early evening. While low-level wind profiles should remain meager, 40-50 knot flow aloft may support transient storm organization, though weak forcing for ascent should preclude a more robust severe thunderstorm threat. To the northwest, broad cyclonic flow aloft over the central Plains/Midwest is expected to amplify over the next 24 hours as a surge of continental air pushes south. Embedded disturbances within the mean cyclonic flow regime will propagate from the central/high Plains towards the Southeast through tonight. Shallow convective showers should develop over the northern Gulf and into coastal LA/MS/AL within a modest warm advection regime ahead of one of these disturbances. A few lightning flashes are possible, but poor mid-level lapse rates and limited ascent should keep thunderstorm coverage below 10%. ..Moore.. 01/18/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0559 AM CST Thu Jan 18 2024 Valid 181300Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... A few thunderstorms may develop across parts of south Florida today. ...Synopsis/Discussion... In mid/upper levels, broadly cyclonic flow over the central/eastern CONUS will amplify again as two connected events occur: 1. Synoptic-scale ridging -- now over the West Coast -- shifts slowly inland, reaching the interior Northwest and western Great Basin by the end of the period. 2. A series of shortwave troughs -- initially evident in moisture-channel imagery from northernmost portions of ON/MB southwestward to central/eastern MT -- dig southward to southeastward and get more in phase. This will lead to a closed or nearly closed 500-mb low over Lake Superior by 12Z tomorrow. The MT perturbation will cross the central Plains to the lower Ohio Valley. In response to these developments, a surface cold front -- analyzed at 11Z across Lake Superior, northwestern WI, southern MN, to a weak low over the northwestern NE Panhandle, to northwestern WY and western MT -- should sweep eastward to southeastward across the remainder of the Plains and Missouri/Mississippi Valleys. By 12Z tomorrow, the front should extend from a low over WV across GA, the FL Panhandle, and the central/southwestern Gulf. This evening and overnight, thunderstorms should develop in a prefrontal convergence zone (and perhaps along the front) near the Loop Current, where air-sea thermodynamic fluxes can yield greatest boundary-layer theta-e with minimized MLCINH. However, this activity should remain west of FL before 12Z. An area of widely scattered to scattered showers, with a few embedded thunderstorms, may develop this afternoon over portions of south FL. Convection will form in a weakly capped, moist, diurnally heated boundary layer, near an older frontal zone now just south of the peninsula. Activity should move eastward to northeastward off the Atlantic Coast, followed by an evening decrease in coverage as the boundary layer stabilizes. Forecast soundings suggest weak midlevel lapse rates will keep buoyancy on the modest side -- with MLCAPE generally 500-1000 J/kg, while low-level flow and shear remain weak. As such, activity should be too disorganized for a categorical severe threat. ..Edwards/Dean.. 01/18/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0559 AM CST Thu Jan 18 2024 Valid 181300Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... A few thunderstorms may develop across parts of south Florida today. ...Synopsis/Discussion... In mid/upper levels, broadly cyclonic flow over the central/eastern CONUS will amplify again as two connected events occur: 1. Synoptic-scale ridging -- now over the West Coast -- shifts slowly inland, reaching the interior Northwest and western Great Basin by the end of the period. 2. A series of shortwave troughs -- initially evident in moisture-channel imagery from northernmost portions of ON/MB southwestward to central/eastern MT -- dig southward to southeastward and get more in phase. This will lead to a closed or nearly closed 500-mb low over Lake Superior by 12Z tomorrow. The MT perturbation will cross the central Plains to the lower Ohio Valley. In response to these developments, a surface cold front -- analyzed at 11Z across Lake Superior, northwestern WI, southern MN, to a weak low over the northwestern NE Panhandle, to northwestern WY and western MT -- should sweep eastward to southeastward across the remainder of the Plains and Missouri/Mississippi Valleys. By 12Z tomorrow, the front should extend from a low over WV across GA, the FL Panhandle, and the central/southwestern Gulf. This evening and overnight, thunderstorms should develop in a prefrontal convergence zone (and perhaps along the front) near the Loop Current, where air-sea thermodynamic fluxes can yield greatest boundary-layer theta-e with minimized MLCINH. However, this activity should remain west of FL before 12Z. An area of widely scattered to scattered showers, with a few embedded thunderstorms, may develop this afternoon over portions of south FL. Convection will form in a weakly capped, moist, diurnally heated boundary layer, near an older frontal zone now just south of the peninsula. Activity should move eastward to northeastward off the Atlantic Coast, followed by an evening decrease in coverage as the boundary layer stabilizes. Forecast soundings suggest weak midlevel lapse rates will keep buoyancy on the modest side -- with MLCAPE generally 500-1000 J/kg, while low-level flow and shear remain weak. As such, activity should be too disorganized for a categorical severe threat. ..Edwards/Dean.. 01/18/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0559 AM CST Thu Jan 18 2024 Valid 181300Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... A few thunderstorms may develop across parts of south Florida today. ...Synopsis/Discussion... In mid/upper levels, broadly cyclonic flow over the central/eastern CONUS will amplify again as two connected events occur: 1. Synoptic-scale ridging -- now over the West Coast -- shifts slowly inland, reaching the interior Northwest and western Great Basin by the end of the period. 2. A series of shortwave troughs -- initially evident in moisture-channel imagery from northernmost portions of ON/MB southwestward to central/eastern MT -- dig southward to southeastward and get more in phase. This will lead to a closed or nearly closed 500-mb low over Lake Superior by 12Z tomorrow. The MT perturbation will cross the central Plains to the lower Ohio Valley. In response to these developments, a surface cold front -- analyzed at 11Z across Lake Superior, northwestern WI, southern MN, to a weak low over the northwestern NE Panhandle, to northwestern WY and western MT -- should sweep eastward to southeastward across the remainder of the Plains and Missouri/Mississippi Valleys. By 12Z tomorrow, the front should extend from a low over WV across GA, the FL Panhandle, and the central/southwestern Gulf. This evening and overnight, thunderstorms should develop in a prefrontal convergence zone (and perhaps along the front) near the Loop Current, where air-sea thermodynamic fluxes can yield greatest boundary-layer theta-e with minimized MLCINH. However, this activity should remain west of FL before 12Z. An area of widely scattered to scattered showers, with a few embedded thunderstorms, may develop this afternoon over portions of south FL. Convection will form in a weakly capped, moist, diurnally heated boundary layer, near an older frontal zone now just south of the peninsula. Activity should move eastward to northeastward off the Atlantic Coast, followed by an evening decrease in coverage as the boundary layer stabilizes. Forecast soundings suggest weak midlevel lapse rates will keep buoyancy on the modest side -- with MLCAPE generally 500-1000 J/kg, while low-level flow and shear remain weak. As such, activity should be too disorganized for a categorical severe threat. ..Edwards/Dean.. 01/18/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0559 AM CST Thu Jan 18 2024 Valid 181300Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... A few thunderstorms may develop across parts of south Florida today. ...Synopsis/Discussion... In mid/upper levels, broadly cyclonic flow over the central/eastern CONUS will amplify again as two connected events occur: 1. Synoptic-scale ridging -- now over the West Coast -- shifts slowly inland, reaching the interior Northwest and western Great Basin by the end of the period. 2. A series of shortwave troughs -- initially evident in moisture-channel imagery from northernmost portions of ON/MB southwestward to central/eastern MT -- dig southward to southeastward and get more in phase. This will lead to a closed or nearly closed 500-mb low over Lake Superior by 12Z tomorrow. The MT perturbation will cross the central Plains to the lower Ohio Valley. In response to these developments, a surface cold front -- analyzed at 11Z across Lake Superior, northwestern WI, southern MN, to a weak low over the northwestern NE Panhandle, to northwestern WY and western MT -- should sweep eastward to southeastward across the remainder of the Plains and Missouri/Mississippi Valleys. By 12Z tomorrow, the front should extend from a low over WV across GA, the FL Panhandle, and the central/southwestern Gulf. This evening and overnight, thunderstorms should develop in a prefrontal convergence zone (and perhaps along the front) near the Loop Current, where air-sea thermodynamic fluxes can yield greatest boundary-layer theta-e with minimized MLCINH. However, this activity should remain west of FL before 12Z. An area of widely scattered to scattered showers, with a few embedded thunderstorms, may develop this afternoon over portions of south FL. Convection will form in a weakly capped, moist, diurnally heated boundary layer, near an older frontal zone now just south of the peninsula. Activity should move eastward to northeastward off the Atlantic Coast, followed by an evening decrease in coverage as the boundary layer stabilizes. Forecast soundings suggest weak midlevel lapse rates will keep buoyancy on the modest side -- with MLCAPE generally 500-1000 J/kg, while low-level flow and shear remain weak. As such, activity should be too disorganized for a categorical severe threat. ..Edwards/Dean.. 01/18/2024 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0559 AM CST Thu Jan 18 2024 Valid 181300Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... A few thunderstorms may develop across parts of south Florida today. ...Synopsis/Discussion... In mid/upper levels, broadly cyclonic flow over the central/eastern CONUS will amplify again as two connected events occur: 1. Synoptic-scale ridging -- now over the West Coast -- shifts slowly inland, reaching the interior Northwest and western Great Basin by the end of the period. 2. A series of shortwave troughs -- initially evident in moisture-channel imagery from northernmost portions of ON/MB southwestward to central/eastern MT -- dig southward to southeastward and get more in phase. This will lead to a closed or nearly closed 500-mb low over Lake Superior by 12Z tomorrow. The MT perturbation will cross the central Plains to the lower Ohio Valley. In response to these developments, a surface cold front -- analyzed at 11Z across Lake Superior, northwestern WI, southern MN, to a weak low over the northwestern NE Panhandle, to northwestern WY and western MT -- should sweep eastward to southeastward across the remainder of the Plains and Missouri/Mississippi Valleys. By 12Z tomorrow, the front should extend from a low over WV across GA, the FL Panhandle, and the central/southwestern Gulf. This evening and overnight, thunderstorms should develop in a prefrontal convergence zone (and perhaps along the front) near the Loop Current, where air-sea thermodynamic fluxes can yield greatest boundary-layer theta-e with minimized MLCINH. However, this activity should remain west of FL before 12Z. An area of widely scattered to scattered showers, with a few embedded thunderstorms, may develop this afternoon over portions of south FL. Convection will form in a weakly capped, moist, diurnally heated boundary layer, near an older frontal zone now just south of the peninsula. Activity should move eastward to northeastward off the Atlantic Coast, followed by an evening decrease in coverage as the boundary layer stabilizes. Forecast soundings suggest weak midlevel lapse rates will keep buoyancy on the modest side -- with MLCAPE generally 500-1000 J/kg, while low-level flow and shear remain weak. As such, activity should be too disorganized for a categorical severe threat. ..Edwards/Dean.. 01/18/2024 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0313 AM CST Thu Jan 18 2024 Valid 211200Z - 261200Z ...DISCUSSION... An upper-level trough over the western U.S. early in the period will slowly shift east toward the Rockies and adjacent High Plains through at least Day 6/Tue. Beyond Tuesday, most medium-range guidance depicts a mean upper trough roughly over the High Plains, with a series of shortwave ejecting east/northeast into the Mid-South/Midwest vicinity Days 7-8/Wed-Thu. This overall pattern will support long-duration deep-layer southwesterly flow across the southern Plains, Lower MS Valley/Gulf coast states and the Mid-South. As a result, Gulf moisture is expected to return northward, first across the Texas coastal vicinity on Day 4/Sun before also increasing across much of the rest of the Gulf coast states the remainder of the period. Given increased southwesterly flow overspreading returning Gulf moisture, at least some low-end severe potential appears possible across coastal TX early in the period. Some severe potential could then shift east across the Gulf Coast states later in the period, (around Day 7 or 8/Wed or Thu) when some guidance shows a stronger shortwave trough ejecting over the Lower MS/TN Valley vicinity in conjunction with a deeper surface low and cold front. Severe potential appears too low early in the period to include 15 percent probabilities. Uncertainty in timing and latitudinal position of the possible late-period shortwave trough also precludes probabilities at this time. Nevertheless, this pattern change could support increasing severe potential with time across Gulf coast areas, which may necessitate probabilities in the coming days. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0313 AM CST Thu Jan 18 2024 Valid 211200Z - 261200Z ...DISCUSSION... An upper-level trough over the western U.S. early in the period will slowly shift east toward the Rockies and adjacent High Plains through at least Day 6/Tue. Beyond Tuesday, most medium-range guidance depicts a mean upper trough roughly over the High Plains, with a series of shortwave ejecting east/northeast into the Mid-South/Midwest vicinity Days 7-8/Wed-Thu. This overall pattern will support long-duration deep-layer southwesterly flow across the southern Plains, Lower MS Valley/Gulf coast states and the Mid-South. As a result, Gulf moisture is expected to return northward, first across the Texas coastal vicinity on Day 4/Sun before also increasing across much of the rest of the Gulf coast states the remainder of the period. Given increased southwesterly flow overspreading returning Gulf moisture, at least some low-end severe potential appears possible across coastal TX early in the period. Some severe potential could then shift east across the Gulf Coast states later in the period, (around Day 7 or 8/Wed or Thu) when some guidance shows a stronger shortwave trough ejecting over the Lower MS/TN Valley vicinity in conjunction with a deeper surface low and cold front. Severe potential appears too low early in the period to include 15 percent probabilities. Uncertainty in timing and latitudinal position of the possible late-period shortwave trough also precludes probabilities at this time. Nevertheless, this pattern change could support increasing severe potential with time across Gulf coast areas, which may necessitate probabilities in the coming days. Read more