Severe Storms

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0237 PM CDT Mon May 01 2023 Valid 012000Z - 021200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS NORTHWEST NEVADA INTO CENTRAL OREGON... ...SUMMARY... Isolated severe thunderstorm gusts may affect parts of a corridor from northwestern Nevada to eastern Oregon, late this afternoon into evening. ...Discussion... No change was made to the previous convective outlook. ..Smith.. 05/01/2023 .PREV DISCUSSION... /ISSUED 1128 AM CDT Mon May 01 2023/ ...Northwest NV into eastern OR this afternoon/evening... A midlevel shortwave trough over northern CA will pivot northward over northwest NV/southern OR, around the eastern periphery of a deepening midlevel low just off the OR/northern CA coasts. Low-level moisture is limited across the Great Basin with dewpoints mainly in the upper 20s to upper 30s F. However, surface heating will result in steep low-level lapse rates/inverted-v profiles with weak buoyancy, which will favor high-based storms in a loose arc later this afternoon. Some storm-scale organization will be possible in an environment of deep-layer, south-southeasterly shear, and the strongest storms may produce strong/isolated severe outflow gusts this afternoon/evening from northwest NV into eastern OR. ...Elsewhere... Isolated lightning flashes will be possible this afternoon across parts of NY/PA where modest surface heating occurs in cloud breaks, beneath cold midlevel temperatures. Isolated lightning flashes may also occur with weak diurnal convection across parts of the central/northern Rockies, in the vicinity of a mean northwest-southeast oriented baroclinic zone. Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1217 PM CDT Mon May 01 2023 Valid 021200Z - 031200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR THE PERMIAN BASIN... ...SUMMARY... Isolated severe gusts are possible over the Permian Basin late Tuesday afternoon through the mid evening. ...Synopsis... An omega block pattern will characterize the flow regime over the Lower 48 states on Tuesday. Two nearly stationary mid-level lows will be located near San Francisco Bay and the Lower Great Lakes. A mid-level ridge will extend from the southern High Plains north-northwestward through the northern Rockies. Surface high pressure will reside over the mid MO Valley with a narrow moisture plume protruding from the lower Rio Grande Valley northwestward into the southern High Plains. The early stage of northwestward moisture return will be ongoing Tuesday across the lower Rio Grande Valley into the Edwards Plateau/Big Bend. The development of a weak lee trough/dryline will focus the northwest periphery of marginal moisture into the Permian Basin by late afternoon. Very strong heating and steep mid-level lapse rates will result in a well-mixed boundary layer and SBCAPE around 1000 J/kg. Low-level southeasterlies veering and strengthening to 20-kt westerly 500-mb flow, will result in around 25-30 effective shear. Model guidance indicates at least widely scattered thunderstorms developing by early evening. Isolated severe gusts may accompany the stronger downdrafts as this activity aggregates into one or two small clusters during the evening before dissipating. ..Smith.. 05/01/2023 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1132 AM CDT Mon May 01 2023 Valid 011700Z - 021200Z No changes are needed to the current Day 1 Fire Weather Outlooks. See previous discussion below. ..Thornton.. 05/01/2023 .PREV DISCUSSION... /ISSUED 1229 AM CDT Mon May 01 2023/ ...Synopsis... Fire weather concerns are expected this afternoon across southern Arizona into southwest New Mexico. Steady pressure falls over the past 24 hours are noted across parts of the Great Basin where early-morning surface observations depict a broad cyclone. The approach of an upper shortwave trough off the CA coast will support broad-scale ascent over the Great Basin, further deepening the surface low over the next 12 hours. In response, southerly low-level winds are expected to increase from northern Mexico into the Southwest and Great Basin. Latest ensemble guidance continues to show high probability of widespread 15-25 mph sustained winds across this region, and deep boundary-layer mixing will support gusts between 25-40 mph - especially over western AZ where mid-level winds are forecast to be stronger. An antecedent dry air mass is noted across the Southwest, which will allow for another day of 10-20% RH. Elevated to critical fire weather conditions are probable for much of the region, but the fire weather concern will primarily reside from southwest NM to southern AZ where ERCs are generally at the 75th percentile or higher after a period of unseasonably warm temperatures and little rainfall over the past 30 days. Sustained critical conditions appear most probable across parts of southwest AZ, but confidence in the spatial coverage remains too limited for additional highlights. ...Minnesota to northern MO... Strong north/northwesterly gradient winds are expected across a broad swath of the eastern Plains/Midwest this afternoon. Sustained winds between 15-25 mph will likely coincide with areas of 25-35% RH to support periods of elevated fire weather conditions. Latest fuel guidance and drought indices suggest fuels are generally unreceptive, but localized fire weather concerns are possible where fuels are sufficiently dry. ...Dry Thunderstorms... 00 UTC soundings from BOI, LKN, SLC, and GJT sampled a very dry air mass (PWAT values 0.4-0.5 inches) with cold temperatures aloft. Mid-level moisture, while meager, is adequate to support high-based convection based on recent lightning trends in southwest ID. This air mass is expected to migrate northward into northern ID/western MT as well as WY to northwest CO, and may support a few dry thunderstorms this afternoon. While this potential is noted, fuels across the region remain too unreceptive to warrant a risk highlight. ...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 1128 AM CDT Mon May 01 2023 Valid 011630Z - 021200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON/EVENING FROM NORTHWEST NV INTO EASTERN OR... ...SUMMARY... Isolated severe thunderstorm gusts may affect parts of a corridor from northwestern Nevada to eastern Oregon, late this afternoon into evening. ...Northwest NV into eastern OR this afternoon/evening... A midlevel shortwave trough over northern CA will pivot northward over northwest NV/southern OR, around the eastern periphery of a deepening midlevel low just off the OR/northern CA coasts. Low-level moisture is limited across the Great Basin with dewpoints mainly in the upper 20s to upper 30s F. However, surface heating will result in steep low-level lapse rates/inverted-v profiles with weak buoyancy, which will favor high-based storms in a loose arc later this afternoon. Some storm-scale organization will be possible in an environment of deep-layer, south-southeasterly shear, and the strongest storms may produce strong/isolated severe outflow gusts this afternoon/evening from northwest NV into eastern OR. ...Elsewhere... Isolated lightning flashes will be possible this afternoon across parts of NY/PA where modest surface heating occurs in cloud breaks, beneath cold midlevel temperatures. Isolated lightning flashes may also occur with weak diurnal convection across parts of the central/northern Rockies, in the vicinity of a mean northwest-southeast oriented baroclinic zone. ..Thompson/Bentley.. 05/01/2023 Read more

No watches are valid as of Sun Apr 30 21:31:01 UTC 2023.

No Mesoscale Discussions are in effect as of Sun Apr 30 21:31:01 UTC 2023.

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0258 PM CDT Sun Apr 30 2023 Valid 302000Z - 011200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR EASTERN NORTH CAROLINA AND SOUTHEAST VIRGINIA... ...SUMMARY... Isolated damaging thunderstorm winds and marginally severe hail will be possible this afternoon from eastern North Carolina to southeast Virginia. ...Discussion... The only change this forecast update is to remove severe probabilities in wake of the squall line over eastern NC. ..Smith.. 04/30/2023 .PREV DISCUSSION... /ISSUED 1126 AM CDT Sun Apr 30 2023/ ...Northeast SC into eastern NC/southeast VA this afternoon... Around the southeast periphery of a deep low over Lake MI, a pronounced shortwave trough will eject quickly northeastward today across the Carolinas and Mid-Atlantic. An associated surface cyclone will likewise move northeastward and deepen from the Carolina Piedmont to the Mid-Atlantic by this evening, as a trailing cold front moves off the Southeast Atlantic Coast. Prior to frontal passage, there will be a window of opportunity for destabilization from northeast SC into eastern NC, in the wake of ongoing rain/clouds across eastern NC. Boundary-layer dewpoints in the mid-upper 60s, surface temperatures warming into the low-mid 70s, and cooling midlevel temperatures will result in MLCAPE of 1000-1500 J/kg and minimal convective inhibition this afternoon. Ongoing thunderstorms in SC along the front and on the nose of the midlevel dry slot will expand some in coverage while spreading northeastward into eastern NC/southeast VA this afternoon. These storms will pose a threat for wind damage and large hail, given the moderate buoyancy/cool midlevel temperatures and straight hodographs. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0258 PM CDT Sun Apr 30 2023 Valid 302000Z - 011200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR EASTERN NORTH CAROLINA AND SOUTHEAST VIRGINIA... ...SUMMARY... Isolated damaging thunderstorm winds and marginally severe hail will be possible this afternoon from eastern North Carolina to southeast Virginia. ...Discussion... The only change this forecast update is to remove severe probabilities in wake of the squall line over eastern NC. ..Smith.. 04/30/2023 .PREV DISCUSSION... /ISSUED 1126 AM CDT Sun Apr 30 2023/ ...Northeast SC into eastern NC/southeast VA this afternoon... Around the southeast periphery of a deep low over Lake MI, a pronounced shortwave trough will eject quickly northeastward today across the Carolinas and Mid-Atlantic. An associated surface cyclone will likewise move northeastward and deepen from the Carolina Piedmont to the Mid-Atlantic by this evening, as a trailing cold front moves off the Southeast Atlantic Coast. Prior to frontal passage, there will be a window of opportunity for destabilization from northeast SC into eastern NC, in the wake of ongoing rain/clouds across eastern NC. Boundary-layer dewpoints in the mid-upper 60s, surface temperatures warming into the low-mid 70s, and cooling midlevel temperatures will result in MLCAPE of 1000-1500 J/kg and minimal convective inhibition this afternoon. Ongoing thunderstorms in SC along the front and on the nose of the midlevel dry slot will expand some in coverage while spreading northeastward into eastern NC/southeast VA this afternoon. These storms will pose a threat for wind damage and large hail, given the moderate buoyancy/cool midlevel temperatures and straight hodographs. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0215 PM CDT Sun Apr 30 2023 Valid 011200Z - 021200Z No changes are needed to the D2 Fire Weather Outlook. See previous discussion below. ..Thornton.. 04/30/2023 .PREV DISCUSSION... /ISSUED 0153 AM CDT Sun Apr 30 2023/ ...Synopsis... As ridging builds over the Rockies and Great Basin with the aforementioned omega block, stronger southwesterly flow aloft will begin to develop across portions of the Southwest on the fringes of an upper low off the West Coast. A deepening surface low over the Great Basin will enhance southerly winds across portions of southern AZ and NM. Here, warm and dry surface conditions are also expected with afternoon RH values below 15% possible. With wind speeds of 15-20 mph overlapping low humidity and somewhat receptive fuels, a few hours of Elevated fire-weather conditions appear likely Monday. The best overlap of drying fuels and windy/dry conditions will be possible across southern Arizona and far southwestern New Mexico, where ERCs are approaching the 75th percentile with poor overnight recoveries expected. While favorable meteorological conditions will likely extended farther north, fuel conditions remain too prohibitive for highlights, given the early season. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0215 PM CDT Sun Apr 30 2023 Valid 011200Z - 021200Z No changes are needed to the D2 Fire Weather Outlook. See previous discussion below. ..Thornton.. 04/30/2023 .PREV DISCUSSION... /ISSUED 0153 AM CDT Sun Apr 30 2023/ ...Synopsis... As ridging builds over the Rockies and Great Basin with the aforementioned omega block, stronger southwesterly flow aloft will begin to develop across portions of the Southwest on the fringes of an upper low off the West Coast. A deepening surface low over the Great Basin will enhance southerly winds across portions of southern AZ and NM. Here, warm and dry surface conditions are also expected with afternoon RH values below 15% possible. With wind speeds of 15-20 mph overlapping low humidity and somewhat receptive fuels, a few hours of Elevated fire-weather conditions appear likely Monday. The best overlap of drying fuels and windy/dry conditions will be possible across southern Arizona and far southwestern New Mexico, where ERCs are approaching the 75th percentile with poor overnight recoveries expected. While favorable meteorological conditions will likely extended farther north, fuel conditions remain too prohibitive for highlights, given the early season. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1211 PM CDT Sun Apr 30 2023 Valid 011200Z - 021200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The severe-thunderstorm threat is expected to be low on Monday. ...Synopsis... The upper-air pattern is forecast to evolve into an omega block as a mid-level low remains nearly stationary over the Great Lakes while a mid-level low migrates southward from near the Vancouver/WA coast to San Francisco Bay by early Tuesday morning. In between these two features, a mid-level ridge will reside over the Rockies/High Plains. In the low levels, surface high pressure will influence conditions across much of the Gulf Coast north-northwestward into the Upper Midwest. Low-topped convection in the form of scattered showers and perhaps a few thunderstorms are possible near the mid-level cold core over Upstate NY. Isolated thunderstorms are also likely to develop across the central Rockies and from eastern WA/ID southward through OR into northwest NV. Small hail perhaps could develop where buoyancy is greatest during the afternoon in western ID and near the Sangre de Cristos, but storm intensity is not expected to reach severe limits. ..Smith.. 04/30/2023 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1211 PM CDT Sun Apr 30 2023 Valid 011200Z - 021200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The severe-thunderstorm threat is expected to be low on Monday. ...Synopsis... The upper-air pattern is forecast to evolve into an omega block as a mid-level low remains nearly stationary over the Great Lakes while a mid-level low migrates southward from near the Vancouver/WA coast to San Francisco Bay by early Tuesday morning. In between these two features, a mid-level ridge will reside over the Rockies/High Plains. In the low levels, surface high pressure will influence conditions across much of the Gulf Coast north-northwestward into the Upper Midwest. Low-topped convection in the form of scattered showers and perhaps a few thunderstorms are possible near the mid-level cold core over Upstate NY. Isolated thunderstorms are also likely to develop across the central Rockies and from eastern WA/ID southward through OR into northwest NV. Small hail perhaps could develop where buoyancy is greatest during the afternoon in western ID and near the Sangre de Cristos, but storm intensity is not expected to reach severe limits. ..Smith.. 04/30/2023 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1141 AM CDT Sun Apr 30 2023 Valid 301700Z - 011200Z No changes are needed to the D1 Fire Weather Outlook. See previous discussion below. ..Thornton.. 04/30/2023 .PREV DISCUSSION... /ISSUED 0151 AM CDT Sun Apr 30 2023/ ...Synopsis... An omega block with a broad mid-level cyclone will dominate the flow pattern for the eastern half of the country through the forecast period. Northwesterly flow aloft is expected over the Plains supporting dry and breezy conditions. Meanwhile, ridging and weaker winds are expected over portions of the Southwest and Rockies, while a cold front moves south. ...Central Plains... In the wake of a cold front moving south across the Plains, dry northwesterly flow is expected over portions of southern NE and northern KS. Surface winds gusting to near 20 mph will overlap with afternoon RH values of 20-25% for a few hours during peak heating. Occurring in a relative minimum of recent precipitation, area fuels are somewhat conducive to fire spread. A few hours of elevated to locally critical fire-weather conditions are possible through the afternoon. ...West TX and eastern NM... Ahead of the surface cold front, westerly downslope winds are expected through the day across portions of eastern NM and west TX. While not overly strong, occasional gusts near 15-20 mph will likely overlap with surface humidity values below 20%. A few hours of locally elevated fire-weather conditions are possible within the dry fuels. However, confidence in spatial coverage is low owing to the modest surface winds. ...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 1141 AM CDT Sun Apr 30 2023 Valid 301700Z - 011200Z No changes are needed to the D1 Fire Weather Outlook. See previous discussion below. ..Thornton.. 04/30/2023 .PREV DISCUSSION... /ISSUED 0151 AM CDT Sun Apr 30 2023/ ...Synopsis... An omega block with a broad mid-level cyclone will dominate the flow pattern for the eastern half of the country through the forecast period. Northwesterly flow aloft is expected over the Plains supporting dry and breezy conditions. Meanwhile, ridging and weaker winds are expected over portions of the Southwest and Rockies, while a cold front moves south. ...Central Plains... In the wake of a cold front moving south across the Plains, dry northwesterly flow is expected over portions of southern NE and northern KS. Surface winds gusting to near 20 mph will overlap with afternoon RH values of 20-25% for a few hours during peak heating. Occurring in a relative minimum of recent precipitation, area fuels are somewhat conducive to fire spread. A few hours of elevated to locally critical fire-weather conditions are possible through the afternoon. ...West TX and eastern NM... Ahead of the surface cold front, westerly downslope winds are expected through the day across portions of eastern NM and west TX. While not overly strong, occasional gusts near 15-20 mph will likely overlap with surface humidity values below 20%. A few hours of locally elevated fire-weather conditions are possible within the dry fuels. However, confidence in spatial coverage is low owing to the modest surface winds. ...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 1126 AM CDT Sun Apr 30 2023 Valid 301630Z - 011200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON FROM NORTHEAST SC ACROSS EASTERN NC TO SOUTHEAST VA... ...SUMMARY... Isolated damaging thunderstorm winds and marginally severe hail will be possible this afternoon from northeast South Carolina to southeast Virginia. ...Northeast SC into eastern NC/southeast VA this afternoon... Around the southeast periphery of a deep low over Lake MI, a pronounced shortwave trough will eject quickly northeastward today across the Carolinas and Mid-Atlantic. An associated surface cyclone will likewise move northeastward and deepen from the Carolina Piedmont to the Mid-Atlantic by this evening, as a trailing cold front moves off the Southeast Atlantic Coast. Prior to frontal passage, there will be a window of opportunity for destabilization from northeast SC into eastern NC, in the wake of ongoing rain/clouds across eastern NC. Boundary-layer dewpoints in the mid-upper 60s, surface temperatures warming into the low-mid 70s, and cooling midlevel temperatures will result in MLCAPE of 1000-1500 J/kg and minimal convective inhibition this afternoon. Ongoing thunderstorms in SC along the front and on the nose of the midlevel dry slot will expand some in coverage while spreading northeastward into eastern NC/southeast VA this afternoon. These storms will pose a threat for wind damage and large hail, given the moderate buoyancy/cool midlevel temperatures and straight hodographs. ..Thompson/Squitieri.. 04/30/2023 Read more

No Mesoscale Discussions are in effect as of Sat Apr 29 21:30:05 UTC 2023.

WW 0183 Status Updates
STATUS REPORT ON WW 183 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 70 SSW CTY TO 25 S VLD. ..MOORE..04/29/23 ATTN...WFO...JAX...MLB...TBW...TAE... STATUS REPORT FOR WT 183 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS FLC001-007-009-017-019-027-029-035-041-049-053-055-057-061-069- 075-081-083-085-093-095-097-101-103-105-107-109-111-115-117-119- 125-127-292140- FL . FLORIDA COUNTIES INCLUDED ARE ALACHUA BRADFORD BREVARD CITRUS CLAY DESOTO DIXIE FLAGLER GILCHRIST HARDEE HERNANDO HIGHLANDS HILLSBOROUGH INDIAN RIVER LAKE LEVY MANATEE MARION MARTIN OKEECHOBEE ORANGE OSCEOLA PASCO PINELLAS POLK PUTNAM ST. JOHNS ST. LUCIE SARASOTA SEMINOLE SUMTER UNION VOLUSIA AMZ454-550-552-555-GMZ830-850-853-292140- CW . ADJACENT COASTAL WATERS INCLUDED ARE Read more

WW 0183 Status Updates
STATUS REPORT ON WW 183 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 70 SSW CTY TO 25 S VLD. ..MOORE..04/29/23 ATTN...WFO...JAX...MLB...TBW...TAE... STATUS REPORT FOR WT 183 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS FLC001-007-009-017-019-027-029-035-041-049-053-055-057-061-069- 075-081-083-085-093-095-097-101-103-105-107-109-111-115-117-119- 125-127-292140- FL . FLORIDA COUNTIES INCLUDED ARE ALACHUA BRADFORD BREVARD CITRUS CLAY DESOTO DIXIE FLAGLER GILCHRIST HARDEE HERNANDO HIGHLANDS HILLSBOROUGH INDIAN RIVER LAKE LEVY MANATEE MARION MARTIN OKEECHOBEE ORANGE OSCEOLA PASCO PINELLAS POLK PUTNAM ST. JOHNS ST. LUCIE SARASOTA SEMINOLE SUMTER UNION VOLUSIA AMZ454-550-552-555-GMZ830-850-853-292140- CW . ADJACENT COASTAL WATERS INCLUDED ARE Read more

WW 183 TORNADO FL CW 291940Z - 300200Z
URGENT - IMMEDIATE BROADCAST REQUESTED Tornado Watch Number 183 NWS Storm Prediction Center Norman OK 340 PM EDT Sat Apr 29 2023 The NWS Storm Prediction Center has issued a * Tornado Watch for portions of Central and north Florida Coastal Waters * Effective this Saturday afternoon and evening from 340 PM until 1000 PM EDT. * Primary threats include... A couple tornadoes possible Scattered damaging wind gusts to 70 mph possible Isolated large hail events to 1.5 inches in diameter possible SUMMARY...Isolated severe storms will remain possible this afternoon close to the Atlantic coast with the sea breeze, and a larger cluster of storms will move inland from the northeast Gulf of Mexico later this afternoon. The initial storms near the Atlantic coast will pose a threat for isolated large hail/damaging gusts, while the Gulf storms moving inland will pose the threat for damaging winds. A couple of tornadoes will also be possible with storm interactions and embedded circulations. The tornado watch area is approximately along and 70 statute miles east and west of a line from 30 miles north of Gainesville FL to 40 miles south southwest of Avon Park FL. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU3). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Tornado Watch means conditions are favorable for tornadoes and severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. && AVIATION...Tornadoes and a few severe thunderstorms with hail surface and aloft to 1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 26035. ...Thompson Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Sat Apr 29 2023 Valid 292000Z - 301200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTION OF THE CENTRAL FLORIDA PENINSULA... ...SUMMARY... Two rounds of severe thunderstorms, with damaging winds, large hail, and a coup[e of tornadoes, are possible across parts of Florida and southern Georgia this afternoon, and again overnight. ...20Z Update... The primary change to this outlook was to confine the category 2/Slight risk to the FL peninsula. A widespread precipitation shield has overspread much of the FL Panhandle and surrounding region, limiting buoyancy inland. Offshore across the Gulf of Mexico, deeper convection associated with an MCS has resulted in tropospheric overturning, lowering confidence in airmass destabilization ahead of an approaching surface low/mid-level trough over the coastal Southeast. Still, an instance or two of damaging gusts, large hail, or a brief tornado remains possible. Otherwise, the previous forecast remains on track, with severe potential remaining in place across the FL Peninsula with the approach of the aforementioned MCS and preceding sea-breeze convection. A second round of strong to potentially severe storms may still occur across the FL Peninsula later tonight into tomorrow morning with the approach of a surface cold front. ..Squitieri.. 04/29/2023 .PREV DISCUSSION... /ISSUED 1125 AM CDT Sat Apr 29 2023/ ...FL area through tonight... A large cluster of thunderstorms over the northeast Gulf of Mexico appears to be developing into an MCS, in advance of a pronounced midlevel shortwave trough over the northwest Gulf coast. The developing MCS is expected to progress east-northeastward over central/north FL later this afternoon/evening, along and south of a stalled front. Boundary-layer dewpoints near 70 F and surface heating in cloud breaks will result in destabilization sufficient to maintain the MCS and an attendant threat for damaging winds late this afternoon. Aside from the MCS, cyclogenesis appears likely near the Southeast Atlantic coast along the stalled front by tonight, as the Gulf of Mexico shortwave trough begins to phase with a deep low over the Great Lakes. There will be some threat for additional storm development overnight in association with the primary Gulf of Mexico shortwave trough and cold front, in the wake of the afternoon MCS. Wind profiles will strengthen with time tonight with the approach of the shortwave trough and cyclogenesis. However, the main concern overnight will be any reductions in moisture/buoyancy by today's convection. Other storms may form this afternoon along the Atlantic coast sea breeze from southeast into east central FL. MLCAPE in excess of 2500 J/kg and effective bulk shear of 35-50 kt (driven by relatively weak low-level flow and stronger flow aloft) will support the potential for organized/supercell storms with the potential to produce isolated large hail and damaging winds. ...Coastal Carolinas late this afternoon into tonight... The surface warm/moist sector will remain near the Atlantic coast this afternoon, and an isolated strong storm may form along the boundary this afternoon in southern NC. By tonight, there will be a gradual increase in vertical shear in response to cyclogenesis, as well as the possibility of a remnant MCV emerging from the Gulf of Mexico MCS. There will be a conditional threat for organized/supercell storms, though the details of thunderstorm coverage/evolution will depend on the future influence of the Gulf of Mexico convection, which is still uncertain this far northeast. Read more