Aggregator

Issued at 100 PM CDT Wed Sep 25 2024 000 WTNT34 KNHC 251751 TCPAT4 BULLETIN Hurricane Helene Intermediate Advisory Number 9A NWS National Hurricane Center Miami FL AL092024 100 PM CDT Wed Sep 25 2024 ...HELENE MOVING INTO THE SOUTHEASTERN GULF OF MEXICO... ...PREPARATIONS TO PROTECT LIFE AND PROPERTY FROM STORM SURGE AND DAMAGING WINDS ALONG THE FLORIDA BIG BEND COAST SHOULD BE RUSHED TO COMPLETION TODAY... SUMMARY OF 100 PM CDT...1800 UTC...INFORMATION ---------------------------------------------- LOCATION...22.0N 86.4W ABOUT 110 MI...175 KM NNE OF COZUMEL MEXICO ABOUT 480 MI...775 KM SSW OF TAMPA FLORIDA MAXIMUM SUSTAINED WINDS...80 MPH...130 KM/H PRESENT MOVEMENT...NNW OR 345 DEGREES AT 10 MPH...17 KM/H MINIMUM CENTRAL PRESSURE...980 MB...28.94 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: None. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Storm Surge Warning is in effect for... * Indian Pass southward to Flamingo * Tampa Bay * Charlotte Harbor A Hurricane Warning is in effect for... * Anclote River to Mexico Beach * Cabo Catoche to Tulum, Mexico including Cozumel A Storm Surge Watch is in effect for... * West of Indian Pass to Mexico Beach A Hurricane Watch is in effect for... * Cuban province of Pinar del Rio * Englewood to Anclote River, including Tampa Bay A Tropical Storm Warning is in effect for... * Florida Keys, including the Dry Tortugas * Flamingo to Anclote River, including Tampa Bay * West of Mexico Beach to the Okaloosa/Walton County Line * Flamingo northward to South Santee River * Lake Okeechobee * Rio Lagartos to Cabo Catoche, Mexico * Cuban provinces of Artemisa, Pinar del Rio, and the Isle of Youth A Tropical Storm Watch is in effect for... * North of South Santee River to Little River Inlet A Storm Surge Warning means there is a danger of life-threatening inundation, from rising water moving inland from the coastline, during the next 36 hours in the indicated locations. For a depiction of areas at risk, please see the National Weather Service Storm Surge Watch/Warning Graphic, available at hurricanes.gov. This is a life-threatening situation. Persons located within these areas should take all necessary actions to protect life and property from rising water and the potential for other dangerous conditions. Promptly follow evacuation and other instructions from local officials. A Hurricane Warning means that hurricane conditions are expected somewhere within the warning area. A warning is typically issued 36 hours before the anticipated first occurrence of tropical-storm-force winds, conditions that make outside preparations difficult or dangerous. Preparations to protect life and property should be rushed to completion. A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area within the next 36 hours. A Storm Surge Watch means there is a possibility of life- threatening inundation, from rising water moving inland from the coastline, in the indicated locations during the next 48 hours. For a depiction of areas at risk, please see the National Weather Service Storm Surge Watch/Warning Graphic, available at hurricanes.gov. A Hurricane Watch means that hurricane conditions are possible within the watch area. A watch is typically issued 48 hours before the anticipated first occurrence of tropical-storm-force winds, conditions that make outside preparations difficult or dangerous. A Tropical Storm Watch means that tropical storm conditions are possible within the watch area. Additional watches or warnings may be required later today or tonight. For storm information specific to your area in the United States, including possible inland watches and warnings, please monitor products issued by your local National Weather Service forecast office. For storm information specific to your area outside of the United States, please monitor products issued by your national meteorological service. DISCUSSION AND OUTLOOK ---------------------- At 100 PM CDT (1800 UTC), the center of Hurricane Helene was located near latitude 22.0 North, longitude 86.4 West. Helene is moving toward the north-northwest near 10 mph (17 km/h). A turn toward the north and north-northeast with an increase in forward speed is expected later today through Thursday, bringing the center of Helene across the eastern Gulf of Mexico and to the Florida Big Bend coast by Thursday evening. After landfall, Helene is expected to slow down and turn toward the northwest over the southeastern United States Friday and Saturday. Data from an Air Force Reserve Hurricane Hunter aircraft indicate that maximum sustained winds remain near 80 mph (130 km/h) with higher gusts. Strengthening is forecast, and Helene is expected to be a major hurricane when it reaches the Florida Big Bend coast Thursday evening. Weakening is expected after landfall, but Helene's fast forward speed will allow strong, damaging winds, especially in gusts, to penetrate well inland across the southeastern United States, including over the higher terrain of the southern Appalachians. Hurricane-force winds extend outward up to 25 miles (35 km) from the center and tropical-storm-force winds extend outward up to 275 miles (445 km). A commercial fishing vessel located near Isla Mujeres, Mexico, recently reported a wind of 63 mph (102 km/h). Dropsonde data indicate that the minimum central pressure has been relatively steady during the past few hours and is estimated to be 980 mb (28.94 inches). HAZARDS AFFECTING LAND ---------------------- Key Messages for Helene can be found in the Tropical Cyclone Discussion under AWIPS header MIATCDAT4 and WMO header WTNT44 KNHC and on the web at hurricanes.gov/text/MIATCDAT4.shtml STORM SURGE: The combination of a life-threatening storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline. The water could reach the following heights above ground somewhere in the indicated areas if the peak surge occurs at the time of high tide... Carrabelle, FL to Chassahowitzka, FL...12-18 ft Apalachicola, FL to Carrabelle, FL...8-12 ft Chassahowitzka, FL to Anclote River, FL...8-12 ft Indian Pass, FL to Apalachicola, FL...6-9 ft Anclote River, FL to Middle of Longboat Key, FL...5-8 ft Tampa Bay...5-8 ft Middle of Longboat Key, FL to Englewood, FL...4-7 ft Englewood, FL to Flamingo, FL...3-5 ft Charlotte Harbor...3-5 ft For a complete depiction of areas at risk of storm surge inundation, please see the National Weather Service Peak Storm Surge Graphic, available at hurricanes.gov/graphics_at4.shtml?peakSurge. Storm surge could raise water levels by as much as 2 to 4 feet above normal tide levels in areas of onshore winds along the southern coast of Pinar del Rio, Cuba, including the Isle of Youth. Storm surge could raise water levels by as much as 3 to 5 feet above ground level in areas of onshore winds within the warning area along the north coast of the Yucatan Peninsula. WIND: Hurricane conditions are expected within the U.S. hurricane warning area late Thursday, with tropical storm conditions beginning Thursday morning. Tropical storm conditions are expected in southern Florida later today and will spread northward across the rest of Florida, Georgia, and South Carolina through Thursday. Tropical storm conditions are possible within the tropical storm watch area in South Carolina beginning on Thursday. Hurricane conditions, especially in gusts, are expected in the hurricane warning area in Mexico during the next several hours. Tropical storm conditions are occurring in the warning area in Cuba, and hurricane conditions are possible for the western portion of Cuba today. RAINFALL: Helene is expected to produce total rain accumulations of 4 to 8 inches over western Cuba, the Cayman Islands, and the northeast Yucatan Peninsula, with isolated totals around 12 inches. This rainfall brings a risk of considerable flooding. A 24-hour rainfall total of 8.60 inches (218.4 mm) was recently reported in Embalse Herradura, Pinar del Rio, Cuba, by the Meteorological Service of Cuba. Over the Southeastern U.S. into the Southern Appalachians, Helene is expected to produce total rain accumulations of 5 to 10 inches with isolated totals around 15 inches. This rainfall will likely result in areas of considerable flash and urban flooding, with areas of significant river flooding. Landslides are possible in areas of steep terrain in the southern Appalachians. For a complete depiction of forecast rainfall associated with Helene, please see the National Weather Service Storm Total Rainfall Graphic, available at hurricanes.gov/graphics_at4.shtml?rainqpf and the Flash Flood Risk graphic at hurricanes.gov/graphics_at4.shtml?ero. TORNADOES: A tornado or two may occur tonight over parts of the Florida Peninsula and southern Alabama. The risk of tornadoes will increase on Thursday, expanding northward across Florida into parts of Georgia and South Carolina. SURF: Swells generated by Helene will affect the southern coast of Cuba and the Yucatan Peninsula of Mexico during the next couple of days. Swells will spread northward toward the west coast of Florida and the northeastern Gulf Coast later today and Thursday. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office. NEXT ADVISORY ------------- Next complete advisory at 400 PM CDT. $$ Forecaster Berg

...HELENE MOVING INTO THE SOUTHEASTERN GULF OF MEXICO... ...PREPARATIONS TO PROTECT LIFE AND PROPERTY FROM STORM SURGE AND DAMAGING WINDS ALONG THE FLORIDA BIG BEND COAST SHOULD BE RUSHED TO COMPLETION TODAY... As of 1:00 PM CDT Wed Sep 25 the center of Helene was located near 22.0, -86.4 with movement NNW at 10 mph. The minimum central pressure was 980 mb with maximum sustained winds of about 80 mph.

000
ABNT20 KNHC 251745
TWOAT

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 PM EDT Wed Sep 25 2024

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

Active Systems:
The National Hurricane Center is issuing advisories on recently
upgraded Hurricane Helene, located over the southeastern Gulf of
Mexico.

Eastern and Central Tropical Atlantic (AL98):
A broad low pressure system associated with a tropical wave located
west of the Cabo Verde Islands continues to produce disorganized
shower and thunderstorm activity. Environmental conditions appear
favorable for gradual development of this system, and a tropical
depression is likely to form in a few days while it moves westward
to west-northwestward across the eastern and central tropical
Atlantic.
* Formation chance through 48 hours...medium...60 percent.
* Formation chance through 7 days...high...80 percent.

Central Subtropical Atlantic (AL99):
A non-tropical area of low pressure is currently located several
hundred miles to the northeast of Bermuda. The system is currently
producing winds up to storm force, and environmental conditions
could support the low developing some subtropical or tropical
characteristics over the next several days as the system moves
generally east-northeastward, remaining over the central Subtropical
Atlantic. Additional information on this system, including storm
warnings, can be found in High Seas Forecasts issued by the National
Weather Service.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 7 days...low...20 percent.

&&
High Seas Forecasts issued by the National Weather Service
can be found under AWIPS header NFDHSFAT1, WMO header FZNT01
KWBC, and online at ocean.weather.gov/shtml/NFDHSFAT1.php

$$
Forecaster Kelly

000
ABPZ20 KNHC 251743
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
1100 AM PDT Wed Sep 25 2024

For the eastern North Pacific...east of 140 degrees west longitude:

Active Systems:
The National Hurricane Center is issuing advisories on recently
re-formed Tropical Storm John, located just south of southwestern
Mexico.

Tropical cyclone formation is not expected during the next 7 days.

&&
Public Advisories on Tropical Storm John are issued under WMO
header WTPZ35 KNHC and under AWIPS header MIATCPEP5.
Forecast/Advisories on Tropical Storm John are issued under
WMO header WTPZ25 KNHC and under AWIPS header MIATCMEP5.

$$
Forecaster Kelly

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 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 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 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 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 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 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 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 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 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 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