SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1223 PM CDT Wed Sep 25 2024 Valid 261200Z - 271200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS SOUTHEAST GEORGIA AND THE SOUTH CAROLINA COASTAL VICINITY... ...SUMMARY... Tropical Cyclone Helene is forecast to move inland across northern Florida and Georgia on Thursday. A risk for tropical-cyclone tornadoes will accompany this system, particularly from the central Florida Peninsula into southeast Georgia and parts of the Midlands and Low Country of South Carolina. ...FL/GA/SC/southeast NC... Latest forecast track guidance from the National Hurricane Center has Hurricane Helene over the eastern Gulf of Mexico (about 225 miles west-southwest of SRQ) early Thursday morning. This system is forecast to continue northward and make landfall in the FL Big Bend vicinity just east of AAF Thursday evening. As the storm moves northward throughout the day, the strong wind field accompanying it will expand northward as well, beginning over the FL Peninsula Thursday morning before reaching into GA during the afternoon and into SC by Thursday evening. These increased winds will result in long, looping hodographs with more than enough low-level shear to support tornadogenesis. As such, buoyancy-related updraft strength/persistence will be the primary factor determining thunderstorm severity and overall tornado potential and frequency. Initial rainbands will likely be impacting the west coast of the FL Peninsula at the beginning of the period before gradually spreading northward/northeastward throughout the day as the system moves northward. Tornadoes are most likely within the low-topped convection within these rainbands, so a low-probability tornado risk will begin early across the FL Peninsula before spreading northeastward over time. A relatively greater tornado risk is anticipated later, with best overlap between these rainbands and the strong low/mid-level flow beginning over FL during the late afternoon and moving into GA and SC during the evening and overnight. Highest tornado potential is still anticipated across coastal GA and SC Low Country after 00Z Friday. ...Southern New England/Hudson Valley... A compact upper low is forecast to progress eastward across southern Quebec and adjacent portions of New England on Thursday. Strong large-scale forcing for ascent will aid in the development of a convective line during the afternoon from southern New England into the Hudson Valley. Buoyancy will be modest, but enhanced mid-level flow through the base of the upper low will support moderate to strong deep-layer vertical shear. Consequently, a few stronger storms capable of damaging gusts are possible. Overall coverage of damaging gusts is currently expected to remain below 5%. ..Mosier.. 09/25/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1223 PM CDT Wed Sep 25 2024 Valid 261200Z - 271200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS SOUTHEAST GEORGIA AND THE SOUTH CAROLINA COASTAL VICINITY... ...SUMMARY... Tropical Cyclone Helene is forecast to move inland across northern Florida and Georgia on Thursday. A risk for tropical-cyclone tornadoes will accompany this system, particularly from the central Florida Peninsula into southeast Georgia and parts of the Midlands and Low Country of South Carolina. ...FL/GA/SC/southeast NC... Latest forecast track guidance from the National Hurricane Center has Hurricane Helene over the eastern Gulf of Mexico (about 225 miles west-southwest of SRQ) early Thursday morning. This system is forecast to continue northward and make landfall in the FL Big Bend vicinity just east of AAF Thursday evening. As the storm moves northward throughout the day, the strong wind field accompanying it will expand northward as well, beginning over the FL Peninsula Thursday morning before reaching into GA during the afternoon and into SC by Thursday evening. These increased winds will result in long, looping hodographs with more than enough low-level shear to support tornadogenesis. As such, buoyancy-related updraft strength/persistence will be the primary factor determining thunderstorm severity and overall tornado potential and frequency. Initial rainbands will likely be impacting the west coast of the FL Peninsula at the beginning of the period before gradually spreading northward/northeastward throughout the day as the system moves northward. Tornadoes are most likely within the low-topped convection within these rainbands, so a low-probability tornado risk will begin early across the FL Peninsula before spreading northeastward over time. A relatively greater tornado risk is anticipated later, with best overlap between these rainbands and the strong low/mid-level flow beginning over FL during the late afternoon and moving into GA and SC during the evening and overnight. Highest tornado potential is still anticipated across coastal GA and SC Low Country after 00Z Friday. ...Southern New England/Hudson Valley... A compact upper low is forecast to progress eastward across southern Quebec and adjacent portions of New England on Thursday. Strong large-scale forcing for ascent will aid in the development of a convective line during the afternoon from southern New England into the Hudson Valley. Buoyancy will be modest, but enhanced mid-level flow through the base of the upper low will support moderate to strong deep-layer vertical shear. Consequently, a few stronger storms capable of damaging gusts are possible. Overall coverage of damaging gusts is currently expected to remain below 5%. ..Mosier.. 09/25/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook RESENT 1 NWS Storm Prediction Center Norman OK 1143 AM CDT Wed Sep 25 2024 Valid 251630Z - 261200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE GULF COAST INTO THE SOUTHERN/CENTRAL APPALACHIANS AND FLORIDA PENINSULA... ...SUMMARY... Isolated severe storms are possible this afternoon from parts of the Southeast and central/southern Appalachians to the Texas/Louisiana Gulf Coast. Some tornado threat may develop across the Florida Peninsula by this evening, in association with Tropical Cyclone Helene. ..Southeast and southern Appalachians... The influence of the upstream mid/upper-level trough and moisture streaming north from the Gulf of Mexico and Helene will lead to widespread precipitation across parts of the Southeast and southern Appalachians. This will tend to limit available buoyancy in some areas, but strong to locally severe storms may occur. Favorable deep-layer winds/shear exist, especially across the southern Appalachians vicinity where a few semi-discrete supercells could occur aside from more prevalent quasi-linear convective bands. Locally damaging wind gusts and perhaps a tornado could accompany the strongest storms, before low/mid-level lapse rates and buoyancy become increasingly weak with time, and an outflow-reinforced effective front sags southward across the region. ...Texas Gulf Coast/Middle Gulf Coast... Somewhat stronger diurnal destabilization will be possible from parts of central/east Texas into Louisiana, and perhaps into Mississippi, with MLCAPE potentially increasing above 1500 J/kg. Isolated to widely scattered thunderstorm development will be possible near a southward-moving cold front. Effective shear will generally range from 25-35 kt, and a few modestly organized storms are possible. Isolated damaging gusts could accompany the strongest storms within this regime. ...Florida Peninsula and Keys... Hurricane Helene's wind field is forecast to be rather large, especially on the east side of the circulation, associated with a strengthening Helene through the afternoon and tonight. Reference the National Hurricane Center for the latest Helene details. This scenario will result in modestly strengthening low-level shear/SRH across the Florida Peninsula during the day, but more so into the evening and overnight after the peak diurnal instability cycle. Instability will likely remain rather weak overall, and details regarding the intensity of any outer rain bands remain uncertain. However, some tropical-cyclone tornado threat could evolve across parts of the Florida Peninsula and Keys, mainly into tonight. ...Eastern Washington/northern Idaho/northwest Montana... While buoyancy is expected to remain quite weak, relatively steep mid-level lapse rates will support thunderstorm potential late this afternoon through early evening from eastern Washington into northern Idaho and northwest Montana, in advance of the approaching shortwave trough. Strong deep-layer flow/shear could support a locally severe storm or two with gusty winds and possibly some hail. ..Guyer/Lyons.. 09/25/2024 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1144 AM CDT Wed Sep 25 2024 Valid 251700Z - 261200Z ...NO CRITICAL AREAS... No changes. See previous discussion below. ..Bentley.. 09/25/2024 .PREV DISCUSSION... /ISSUED 0113 AM CDT Wed Sep 25 2024/ ...Synopsis... A trough will traverse the northern portion of the western US ridge today, bringing enhanced mid-level flow over the Cascades into western Washington and Oregon. Across southwestern Oregon, sustained winds around 15-20 mph will overlap relative humidity reductions to around 20-25 percent. Elevated fire weather conditions will be possible. Receptive fuels in this region are spotty, which leads to low confidence in including an area at this time. In the lee of the Bighorn Mountains in Wyoming, some Elevated to Critical fire weather conditions will be possible. Overall, sustained Elevated to Critical wind speeds appear brief and localized. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook RESENT 2 NWS Storm Prediction Center Norman OK 0823 AM CDT Wed Sep 25 2024 Valid 251300Z - 261200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE GULF COAST INTO THE SOUTHERN/CENTRAL APPALACHIANS AND FLORIDA PENINSULA... ...SUMMARY... Isolated severe storms are possible this afternoon from parts of the Southeast and central/southern Appalachians to the Texas/Louisiana Gulf Coast. Some tornado threat may develop across the Florida Peninsula by this evening, in association with Tropical Cyclone Helene. ...Southeast and southern Appalachians... Widespread precipitation is expected from parts of the Southeast into the southern Appalachians, due to the combined influence of the mid/upper-level flow to the west and moisture streaming north from the Gulf of Mexico and Helene. While this will tend to limit available buoyancy in some areas, strong to locally severe storms will be possible with initial development, with preconvective MLCAPE of around 1000 J/kg possible. This will generally be coincident with favorable deep-layer shear, especially across the southern Appalachians vicinity where a few supercells could occur pending sufficient destabilization. Locally damaging wind gusts and perhaps a tornado could accompany the strongest storms, before low/mid-level lapse rates and buoyancy become increasingly weak with time, and an outflow-reinforced front sags southward across the region. ...Texas Gulf Coast/Middle Gulf Coast... Somewhat stronger diurnal destabilization will be possible from parts of central/east Texas into Louisiana, and perhaps into Mississippi, with MLCAPE potentially increasing above 1500 J/kg. Isolated to widely scattered thunderstorm development will be possible near a southward-moving cold front. Effective shear will generally range from 25-35 kt, and a few modestly organized storms are possible. Isolated damaging gusts could accompany the strongest storms within this regime. ...Florida Peninsula and Keys... Helene's wind field is forecast to be rather large, especially on the east side of the circulation, associated with what is expected to be a strengthening Helene through the afternoon and night. Reference the National Hurricane Center for the latest Helene details. This scenario will result in modestly strengthening low-level shear/SRH across the Florida Peninsula during the day, but more so into the evening and overnight after the peak diurnal instability cycle. Instability will likely remain rather weak overall, and details regarding the intensity of any outer rain bands remain uncertain. However, some tropical-cyclone tornado threat could evolve across parts of the Florida Peninsula and Keys, mainly into tonight. ...Eastern Washington/northern Idaho/northwest Montana... While buoyancy is expected to remain quite weak, relatively steep mid-level lapse rates will support thunderstorm potential late this afternoon through early evening from eastern Washington into northern Idaho and northwest Montana, in advance of the approaching shortwave trough. Most guidance suggests that instability will remain too weak for an organized severe threat, although rather strong deep-layer flow/shear could support a strong storm or two with locally gusty winds and small hail. Subsequent outlooks will reevaluate the possibility of introducing low severe probabilities. ...Upper Ohio Valley to the Lower Great Lakes... Weak to locally moderate buoyancy may develop later today from parts of the upper Ohio Valley into the lower Great Lakes region, between a weakening cold front approaching from the west, and a slow-moving warm front draped from central Pennsylvania into western New York. Moderate southwesterly midlevel flow will support effective shear of 35-45 kt, sufficient for storm organization. However, with persistent cloud cover and mid-level lapse rates expected to remain rather weak, storm intensity and any attendant severe threat could be relatively limited. Confidence in sufficient destabilization remains too low to add severe probabilities. ..Guyer/Broyles.. 09/25/2024 Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0238 AM CDT Wed Sep 25 2024 Valid 281200Z - 031200Z ...DISCUSSION... Severe potential is expected to remain low during the Day 4-8 period. The upper cyclone over the Mid-South on Day 4/Sat slowly weaken an meander east/northeast through Day 5/Sun. General upper troughing over the eastern third of the CONUS will then be reinforced by a shortwave trough developing east from the northern Plains to the Northeast Days 6-8/Mon-Wed. As this shortwave trough shifts east early next week, a surface cold front will sweep across the Midwest. However, severe potential associated with this system will be mitigated by weak instability and poor alignment of stronger vertical shear. Meanwhile, an upper ridge will persist over the Great Basin and portions of the Plains, with generally weak deep-layer flow expected across these areas. Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0153 AM CDT Wed Sep 25 2024 Valid 271200Z - 281200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF NORTH CAROLINA INTO SOUTHERN VIRGINIA... ...SUMMARY... A risk for a couple of tornadoes and damaging thunderstorm wind gusts exists across parts of North Carolina into southern Virginia on Friday. ...NC/VA... Strong low to midlevel southeasterly flow fields associated with the remnants of Tropical Cyclone Helene will persist through Friday afternoon across the southern Mid-Atlantic vicinity. Onshore low-level flow will maintain a high theta-e airmass, with surface dewpoints in the mid 70s F expected. Forecast soundings across the area show favorable low-level hodographs supporting rotation within cells in northwest moving convective bands. While lapse rates will remain poor, rich boundary-layer moisture should provide enough low-level instability to support occasional strong gusts and a couple of tornadoes through late afternoon/early evening. The northward extent of severe potential will be limited by weakening deep-layer flow beyond the 21-00z time frame and a cold front sagging southeast across VA. ..Leitman.. 09/25/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0153 AM CDT Wed Sep 25 2024 Valid 271200Z - 281200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF NORTH CAROLINA INTO SOUTHERN VIRGINIA... ...SUMMARY... A risk for a couple of tornadoes and damaging thunderstorm wind gusts exists across parts of North Carolina into southern Virginia on Friday. ...NC/VA... Strong low to midlevel southeasterly flow fields associated with the remnants of Tropical Cyclone Helene will persist through Friday afternoon across the southern Mid-Atlantic vicinity. Onshore low-level flow will maintain a high theta-e airmass, with surface dewpoints in the mid 70s F expected. Forecast soundings across the area show favorable low-level hodographs supporting rotation within cells in northwest moving convective bands. While lapse rates will remain poor, rich boundary-layer moisture should provide enough low-level instability to support occasional strong gusts and a couple of tornadoes through late afternoon/early evening. The northward extent of severe potential will be limited by weakening deep-layer flow beyond the 21-00z time frame and a cold front sagging southeast across VA. ..Leitman.. 09/25/2024 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0143 AM CDT Wed Sep 25 2024 Valid 261200Z - 271200Z ...NO CRITICAL AREAS... ...Synopsis... Fire weather concerns are expected to be low on Thursday. Hurricane Helene will be absorbed into the upper-level flow across the eastern US with widespread rainfall anticipated. Across the central and western US, a ridge of high pressure will remain in place with generally light winds. As such, no overlap of critically dry fuels with Elevated/Critical conditions is expected. ..Thornton.. 09/25/2024 ...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 0143 AM CDT Wed Sep 25 2024 Valid 261200Z - 271200Z ...NO CRITICAL AREAS... ...Synopsis... Fire weather concerns are expected to be low on Thursday. Hurricane Helene will be absorbed into the upper-level flow across the eastern US with widespread rainfall anticipated. Across the central and western US, a ridge of high pressure will remain in place with generally light winds. As such, no overlap of critically dry fuels with Elevated/Critical conditions is expected. ..Thornton.. 09/25/2024 ...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 0113 AM CDT Wed Sep 25 2024 Valid 251200Z - 261200Z ...NO CRITICAL AREAS... ...Synopsis... A trough will traverse the northern portion of the western US ridge today, bringing enhanced mid-level flow over the Cascades into western Washington and Oregon. Across southwestern Oregon, sustained winds around 15-20 mph will overlap relative humidity reductions to around 20-25 percent. Elevated fire weather conditions will be possible. Receptive fuels in this region are spotty, which leads to low confidence in including an area at this time. In the lee of the Bighorn Mountains in Wyoming, some Elevated to Critical fire weather conditions will be possible. Overall, sustained Elevated to Critical wind speeds appear brief and localized. ..Thornton.. 09/25/2024 ...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 0113 AM CDT Wed Sep 25 2024 Valid 251200Z - 261200Z ...NO CRITICAL AREAS... ...Synopsis... A trough will traverse the northern portion of the western US ridge today, bringing enhanced mid-level flow over the Cascades into western Washington and Oregon. Across southwestern Oregon, sustained winds around 15-20 mph will overlap relative humidity reductions to around 20-25 percent. Elevated fire weather conditions will be possible. Receptive fuels in this region are spotty, which leads to low confidence in including an area at this time. In the lee of the Bighorn Mountains in Wyoming, some Elevated to Critical fire weather conditions will be possible. Overall, sustained Elevated to Critical wind speeds appear brief and localized. ..Thornton.. 09/25/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1252 AM CDT Wed Sep 25 2024 Valid 261200Z - 271200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHEAST GEORGIA INTO THE SOUTHERN SC COASTAL VICINITY... ...SUMMARY... Tropical Cyclone Helene is forecast to move inland across northern Florida and Georgia on Thursday. A risk for tropical-cyclone tornadoes will accompany this system, particularly from the central Florida Peninsula into southeast Georgia and parts of the Midlands and Low Country of South Carolina. ...FL/GA/SC/southeast NC... Latest forecast track guidance from the National Hurricane Center has Helene making landfall in the vicinity of the Florida Big Bend Thursday evening. As the storm tracks northward across the eastern Gulf of Mexico, low and mid level flow fields will increase from central FL into southeast GA and coastal SC during the day. Forecast soundings from most forecast guidance show very large, favorably curved low-level hodographs for rotating supercells within convective bands well east/northeast of the center of Helene. Surface dewpoints are forecast to increase into the mid 70s F, resulting in greater than 125 J/kg 0-3 km MLCAPE from north FL into southeast GA and southern coastal SC. Furthermore, looking at historical tropical cyclone tornado data, adjusting for the expected track/storm motion of Helene and even distance from the center, previous cyclone analogs have produced several tornadoes within the favored northeast quadrant. Given a consistent, favorable signal across ensemble, deterministic, CAMs and calibrated guidance, an Enhanced risk (level 3 of 5) has been included, driven by a 10 percent tornado probability, across southeast GA into southern coastal SC. ..Leitman.. 09/25/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1252 AM CDT Wed Sep 25 2024 Valid 261200Z - 271200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHEAST GEORGIA INTO THE SOUTHERN SC COASTAL VICINITY... ...SUMMARY... Tropical Cyclone Helene is forecast to move inland across northern Florida and Georgia on Thursday. A risk for tropical-cyclone tornadoes will accompany this system, particularly from the central Florida Peninsula into southeast Georgia and parts of the Midlands and Low Country of South Carolina. ...FL/GA/SC/southeast NC... Latest forecast track guidance from the National Hurricane Center has Helene making landfall in the vicinity of the Florida Big Bend Thursday evening. As the storm tracks northward across the eastern Gulf of Mexico, low and mid level flow fields will increase from central FL into southeast GA and coastal SC during the day. Forecast soundings from most forecast guidance show very large, favorably curved low-level hodographs for rotating supercells within convective bands well east/northeast of the center of Helene. Surface dewpoints are forecast to increase into the mid 70s F, resulting in greater than 125 J/kg 0-3 km MLCAPE from north FL into southeast GA and southern coastal SC. Furthermore, looking at historical tropical cyclone tornado data, adjusting for the expected track/storm motion of Helene and even distance from the center, previous cyclone analogs have produced several tornadoes within the favored northeast quadrant. Given a consistent, favorable signal across ensemble, deterministic, CAMs and calibrated guidance, an Enhanced risk (level 3 of 5) has been included, driven by a 10 percent tornado probability, across southeast GA into southern coastal SC. ..Leitman.. 09/25/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0104 AM CDT Wed Sep 25 2024 Valid 251200Z - 261200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE GULF COAST INTO THE SOUTHERN/CENTRAL APPALACHIANS AND FLORIDA PENINSULA... ...SUMMARY... Isolated severe storms are possible later today from parts of the Southeast and central/southern Appalachians to the Texas/Louisiana Gulf Coast. Some tornado threat may develop across the Florida Peninsula by this evening, in association with Tropical Cyclone Helene. ...Synopsis... The upper-level pattern across much of the CONUS will become rather complex today and tonight. Tropical Cyclone Helene is forecast to intensify as a hurricane as it begins to move north-northeastward across the eastern Gulf of Mexico; see NHC forecasts and advisories for more information. A mid/upper-level low that will initially be over the mid MS Valley is expected to slow down and eventually move southward, as it begins to interact with Helene. A northern-stream mid/upper-level trough is expected to amplify as it moves east-southeastward toward the lower Great Lakes region. A seasonably strong mid/upper-level shortwave trough will move across the Northwest through the day and into the evening. ...Parts of the TX Gulf Coast into the Southeast and southern Appalachians... Widespread precipitation is expected from parts of the Southeast into the southern Appalachians, due to the combined influence of the mid/upper-level flow to the west and moisture streaming north from the Gulf of Mexico and Helene. While this will tend to limit available buoyancy with time, a few strong storms will be possible with initial development, with preconvective MLCAPE of around 1000 J/kg and generally favorable deep-layer shear. Locally damaging gusts and perhaps a tornado could accompany the strongest storms, before low/midlevel lapse rates and buoyancy become increasingly weak with time, and an outflow-reinforced front sags southward across the region. Compared to areas farther east, somewhat stronger diurnal destabilization will be possible from parts of central/east TX into LA, and perhaps into MS, with MLCAPE potentially increasing above 1500 J/kg. Isolated to widely scattered storm development will be possible near a southward-moving cold front. Effective shear will generally range from 25-35 kt, and a few modestly organized storms are possible. Isolated damaging gusts could accompany the strongest storms within this regime. ...Florida Peninsula and Keys... Helene's wind field is forecast to be rather large, especially on the east side of the circulation. This will result in strengthening low-level shear/SRH across the Florida Peninsula during the day and especially into the evening/overnight. Instability will likely remain rather weak, and details regarding the intensity of any outer rain bands remain uncertain, but some tropical-cyclone tornado threat could evolve across parts of the peninsula and Keys, especially later in the period. ...Upper Ohio Valley into the lower Great Lakes... Weak to locally moderate buoyancy may develop later today from parts of the upper OH Valley into the lower Great Lakes region, between a weakening cold front approaching from the west, and a slow-moving warm front draped from central PA into western NY. Moderate southwesterly midlevel flow will support effective shear of 35-45 kt, sufficient for storm organization. However, with midlevel lapse rates expected to remain rather weak, storm intensity and any attendant severe threat could be relatively limited. Confidence in sufficient destabilization is too low to add probabilities at this time. ...Eastern WA into northern ID and northwest MT... While buoyancy is expected to remain quite weak, relatively steep midlevel lapse rates will support thunderstorm potential from eastern WA into northern ID and northwest MT, in advance of the approaching shortwave trough. Most guidance suggests that instability will remain too weak for an organized severe threat, though rather strong deep-layer flow/shear could support a strong storm or two with locally gusty winds and small hail. Severe probabilities may eventually be needed if confidence increases regarding the development of sufficient instability. ..Dean/Thornton.. 09/25/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0104 AM CDT Wed Sep 25 2024 Valid 251200Z - 261200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE GULF COAST INTO THE SOUTHERN/CENTRAL APPALACHIANS AND FLORIDA PENINSULA... ...SUMMARY... Isolated severe storms are possible later today from parts of the Southeast and central/southern Appalachians to the Texas/Louisiana Gulf Coast. Some tornado threat may develop across the Florida Peninsula by this evening, in association with Tropical Cyclone Helene. ...Synopsis... The upper-level pattern across much of the CONUS will become rather complex today and tonight. Tropical Cyclone Helene is forecast to intensify as a hurricane as it begins to move north-northeastward across the eastern Gulf of Mexico; see NHC forecasts and advisories for more information. A mid/upper-level low that will initially be over the mid MS Valley is expected to slow down and eventually move southward, as it begins to interact with Helene. A northern-stream mid/upper-level trough is expected to amplify as it moves east-southeastward toward the lower Great Lakes region. A seasonably strong mid/upper-level shortwave trough will move across the Northwest through the day and into the evening. ...Parts of the TX Gulf Coast into the Southeast and southern Appalachians... Widespread precipitation is expected from parts of the Southeast into the southern Appalachians, due to the combined influence of the mid/upper-level flow to the west and moisture streaming north from the Gulf of Mexico and Helene. While this will tend to limit available buoyancy with time, a few strong storms will be possible with initial development, with preconvective MLCAPE of around 1000 J/kg and generally favorable deep-layer shear. Locally damaging gusts and perhaps a tornado could accompany the strongest storms, before low/midlevel lapse rates and buoyancy become increasingly weak with time, and an outflow-reinforced front sags southward across the region. Compared to areas farther east, somewhat stronger diurnal destabilization will be possible from parts of central/east TX into LA, and perhaps into MS, with MLCAPE potentially increasing above 1500 J/kg. Isolated to widely scattered storm development will be possible near a southward-moving cold front. Effective shear will generally range from 25-35 kt, and a few modestly organized storms are possible. Isolated damaging gusts could accompany the strongest storms within this regime. ...Florida Peninsula and Keys... Helene's wind field is forecast to be rather large, especially on the east side of the circulation. This will result in strengthening low-level shear/SRH across the Florida Peninsula during the day and especially into the evening/overnight. Instability will likely remain rather weak, and details regarding the intensity of any outer rain bands remain uncertain, but some tropical-cyclone tornado threat could evolve across parts of the peninsula and Keys, especially later in the period. ...Upper Ohio Valley into the lower Great Lakes... Weak to locally moderate buoyancy may develop later today from parts of the upper OH Valley into the lower Great Lakes region, between a weakening cold front approaching from the west, and a slow-moving warm front draped from central PA into western NY. Moderate southwesterly midlevel flow will support effective shear of 35-45 kt, sufficient for storm organization. However, with midlevel lapse rates expected to remain rather weak, storm intensity and any attendant severe threat could be relatively limited. Confidence in sufficient destabilization is too low to add probabilities at this time. ...Eastern WA into northern ID and northwest MT... While buoyancy is expected to remain quite weak, relatively steep midlevel lapse rates will support thunderstorm potential from eastern WA into northern ID and northwest MT, in advance of the approaching shortwave trough. Most guidance suggests that instability will remain too weak for an organized severe threat, though rather strong deep-layer flow/shear could support a strong storm or two with locally gusty winds and small hail. Severe probabilities may eventually be needed if confidence increases regarding the development of sufficient instability. ..Dean/Thornton.. 09/25/2024 Read more

WW 0682 Status Updates
STATUS REPORT ON WW 682 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 15 NNE DUA TO 35 S CQB TO 10 SE CQB TO 20 S TUL. ..THORNTON..09/25/24 ATTN...WFO...OUN...TSA... STATUS REPORT FOR WS 682 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS OKC005-029-063-091-107-111-121-123-133-250440- OK . OKLAHOMA COUNTIES INCLUDED ARE ATOKA COAL HUGHES MCINTOSH OKFUSKEE OKMULGEE PITTSBURG PONTOTOC SEMINOLE THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

WW 682 SEVERE TSTM OK 242245Z - 250400Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 682 NWS Storm Prediction Center Norman OK 545 PM CDT Tue Sep 24 2024 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Central Oklahoma * Effective this Tuesday afternoon and evening from 545 PM until 1100 PM CDT. * Primary threats include... Scattered large hail and isolated very large hail events to 2 inches in diameter possible Isolated damaging wind gusts to 70 mph possible SUMMARY...Widely scattered thunderstorms will intensify early this evening across central Oklahoma and drift eastward across the watch area. Initial storms will pose a risk of large hail, with an increasing threat of gusty/damaging winds later this evening. The severe thunderstorm watch area is approximately along and 50 statute miles north and south of a line from 35 miles northwest of Chickasha OK to 15 miles east northeast of Mcalester OK. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU2). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for 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. Severe thunderstorms can and occasionally do produce tornadoes. && OTHER WATCH INFORMATION...CONTINUE...WW 681... AVIATION...A few severe thunderstorms with hail surface and aloft to 2 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 28030. ...Hart Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0759 PM CDT Tue Sep 24 2024 Valid 250100Z - 251200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF CENTRAL/SOUTHERN OK... ...SUMMARY... A few severe storms remain possible this evening across parts of central and southern Oklahoma into north Texas. Strong to locally severe storms also remain possible across parts of the Ohio and Tennessee Valleys into the southern Appalachians region. ...Central OK into north TX... A hail-producing supercell that earlier moved through the OKC metro area has weakened, but additional development is underway across central OK. A cluster of strong to locally severe storms may continue southeastward into north TX through late evening, with moderate buoyancy and relatively strong deep-layer shear continuing to support a threat for at least isolated hail and damaging wind. Increasing CINH should eventually result in a weakening trend, though a few stronger elevated storms will remain possible into the overnight hours. ...Ohio/Tennessee Valleys into the southern Appalachians... Scattered thunderstorms are ongoing this evening across parts of the OH/TN Valleys into the southern Appalachians, within a relatively moist and favorably sheared environment. A gradual decreasing trend is expected to continue with time, due to diurnal cooling and weakening instability. However, ascent attendant to a mid/upper-level trough digging southeastward from the lower MO/mid MS Valley will help to sustain multicell clusters and possibly a couple supercells into late evening, with a threat of isolated damaging gusts and hail. ..Dean.. 09/25/2024 Read more

MD 2105 CONCERNING SEVERE THUNDERSTORM WATCH 681... FOR EASTERN KY/TN INTO SOUTHWEST WV/WESTERN VA
Mesoscale Discussion 2105 NWS Storm Prediction Center Norman OK 0552 PM CDT Tue Sep 24 2024 Areas affected...Eastern KY/TN into southwest WV/western VA Concerning...Severe Thunderstorm Watch 681... Valid 242252Z - 250045Z The severe weather threat for Severe Thunderstorm Watch 681 continues. SUMMARY...Some hail/wind threat continues with scattered storms this evening. DISCUSSION...Short-wave trough is ejecting across the OH Valley early this evening and scattered strong/severe convection continues within the warm-advection zone, well ahead of the front. Over the last few hours, greatest concentration of robust, long-lived updrafts/supercells is beneath the strongest mid-level flow across eastern KY/northeast TN. Radar data suggests at least 4-6 supercells, extending 50mi either side of the TN/KY border, moving east-northeast toward western VA/southwest WV. However, air mass is notably less buoyant downstream and these updrafts will encounter increasingly hostile environment across the higher terrain and points east. Until then, hail/wind threat will continue with these storms. ..Darrow.. 09/24/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...RNK...RLX...MRX...JKL...LMK...OHX... LAT...LON 37058475 38078251 37298155 36198246 36218544 37058475 Read more