• Helene Becomes a Cat 2

    From Dumas Walker@21:1/175 to All on Thu Sep 26 08:51:00 2024
    677
    WTNT34 KNHC 261139
    TCPAT4

    BULLETIN
    Hurricane Helene Intermediate Advisory Number 12A
    NWS National Hurricane Center Miami FL AL092024
    700 AM CDT Thu Sep 26 2024

    ...HELENE BECOMES A CATEGORY 2 HURRICANE WITH SIGNIFICANT
    ADDITIONAL STRENGTHENING EXPECTED BEFORE LANDFALL IN FLORIDA...

    ...PREPARATIONS TO PROTECT LIFE AND PROPERTY SHOULD BE RUSHED TO COMPLETION...

    SUMMARY OF 700 AM CDT...1200 UTC...INFORMATION ----------------------------------------------
    LOCATION...24.5N 85.9W
    ABOUT 320 MI...515 KM SW OF TAMPA FLORIDA
    ABOUT 365 MI...585 KM S OF APALACHICOLA FLORIDA
    MAXIMUM SUSTAINED WINDS...100 MPH...155 KM/H
    PRESENT MOVEMENT...NNE OR 15 DEGREES AT 12 MPH...19 KM/H
    MINIMUM CENTRAL PRESSURE...960 MB...28.35 INCHES

    WATCHES AND WARNINGS
    --------------------
    CHANGES WITH THIS ADVISORY:

    None.

    SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

    A Storm Surge Warning is in effect for...
    * Mexico Beach eastward and southward to Flamingo
    * Tampa Bay
    * Charlotte Harbor

    A Hurricane Warning is in effect for...
    * Anclote River to Mexico Beach

    A Hurricane Watch is in effect for...
    * 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 Little River Inlet
    * Lake Okeechobee
    * Cuban provinces of Artemisa, Pinar del Rio, and the Isle of Youth

    A Storm Surge Warning means there is a danger of life-threatening
    inundation, from rising water moving inland from the coastline. 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. 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.

    A Storm Surge Watch means there is a possibility of life-
    threatening inundation, from rising water moving inland from the
    coastline. 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.

    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 700 AM CDT (1200 UTC), the center of Hurricane Helene was located
    near latitude 24.5 North, longitude 85.9 West. Helene is moving
    toward the north-northeast near 12 mph (19 km/h). This general
    motion is expected to continued with a significant increase in
    forward speed during the next 24 hours. On the forecast track,
    Helene will move across the eastern Gulf of Mexico today and cross
    the Florida Big Bend coast this evening or early Friday morning.
    After landfall, Helene is expected to turn northwestward and slow
    down over the Tennessee Valley on Friday and Saturday.

    Maximum sustained winds have increased to near 100 mph (155 km/h)
    with higher gusts. Additional strengthening is forecast, and Helene
    is expected to be a major hurricane when it reaches the Florida Big
    Bend coast this 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 60 miles (95 km) from
    the center and tropical-storm-force winds extend outward up to 345
    miles (555 km). The Key West Naval Air Station recently reported
    sustained winds of 41 mph (66 km/h) and a wind gust of 55 mph (89
    km/h). An observation in Sand Key recently reported sustained
    winds of 45 mph (72 km/h) and a gust to 58 mph (93 km/h).

    The estimated minimum central pressure based on data from the
    NOAA and Air Force Reserve Hurricane Hunter aircraft is 960 mb (28.35 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 Suwannee River, FL...15-20 ft
    Apalachicola, FL to Carrabelle, FL...10-15 ft
    Suwannee River, FL to Chassahowitzka, FL...10-15 ft
    Chassahowitzka, FL to Anclote River, FL...8-12 ft
    Indian Pass, FL to Apalachicola, FL...6-10 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
    East of Mexico Beach, FL to Indian Pass, FL...3-5 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.

    WIND: Hurricane conditions are expected within the U.S. hurricane
    warning area late today. Tropical storm conditions have
    already begun in the Florida Keys and portions of south
    Florida, and these conditions are expected to spread northward
    across the state and into Georgia and South Carolina through tonight.

    Tropical storm conditions are expected over portions of the warning
    area in western Cuba during the next few hours.

    RAINFALL: Hurricane 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.

    Over portions of the Southeastern U.S. into the Southern
    Appalachians, Helene is expected to produce total rain accumulations
    of 6 to 12 inches with isolated totals around 18 inches. This
    rainfall will likely result in catastrophic and potentially
    life-threatening flash and urban flooding, along with significant
    river flooding. Numerous landslides are expected in steep terrain
    across the southern Appalachians.

    For a complete depiction of forecast rainfall associated with
    Hurricane 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: The risk for several tornadoes will gradually increase
    today through tonight. The greatest threat is expected from parts of
    northern Florida into southeast Georgia, the Midlands and Low
    Country of South Carolina, and southern North Carolina.

    SURF: Swells generated by Helene will affect much of Florida and
    the coasts of Georgia and the Carolinas during the next couple of
    days. Swells will also continue across portions of Cuba and the
    Yucatan Peninsula through tonight. 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 1000 AM CDT.

    $$
    Forecaster Cangialosi
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