From NOAA Hurricane Center:
BULLETIN
Tropical Storm Helene Intermediate Advisory Number 5A
NWS National Hurricane Center Miami FL AL092024
200 PM EDT Tue Sep 24 2024
…HELENE ORGANIZING OVER THE NORTHWESTERN CARIBBEAN SEA…
…HURRICANE AND STORM SURGE WATCHES REMAIN IN EFFECT FOR PORTIONS
OF THE FLORIDA GULF COAST…
SUMMARY OF 200 PM EDT…1800 UTC…INFORMATION
———————————————-
LOCATION…19.4N 84.5W
ABOUT 175 MI…280 KM ESE OF COZUMEL MEXICO
ABOUT 175 MI…280 KM S OF THE WESTERN TIP OF CUBA
MAXIMUM SUSTAINED WINDS…45 MPH…75 KM/H
PRESENT MOVEMENT…WNW OR 295 DEGREES AT 12 MPH…19 KM/H
MINIMUM CENTRAL PRESSURE…999 MB…29.50 INCHES
WATCHES AND WARNINGS
——————–
CHANGES WITH THIS ADVISORY:
The government of the Cayman Islands has discontinued the Tropical
Storm Warning for Grand Cayman.
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Storm Surge Watch is in effect for…
* Indian Pass southward to Flamingo
* Tampa Bay
* Charlotte Harbor
A Hurricane Watch is in effect for…
* Cabo Catoche to Tulum, Mexico
* Cuban province of Pinar del Rio
* Englewood to Indian Pass
* Tampa Bay
A Tropical Storm Warning is in effect for…
* Dry Tortugas
* Lower Florida Keys west of the Seven Mile Bridge
* Rio Lagartos to Tulum, Mexico
* Cuban provinces of Artemisa, Pinar del Rio, and the Isle of Youth
A Tropical Storm Watch is in effect for…
* Middle Florida Keys from the Seven Mile Bridge to the Channel 5
Bridge
* Flamingo to south of Englewood
* West of Indian Pass to Walton Bay County line
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 Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area within the next 36 hours.
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, generally within 48 hours.
Wind and storm surge warnings will likely be required for the
U.S. later today.
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 200 PM EDT (1800 UTC), the center of Tropical Storm Helene was
located near latitude 19.4 North, longitude 84.5 West. Helene has
been wobbling a bit now that a well-defined has just recently
formed, but the longer-term motion is toward the west-northwest
near 12 mph (19 km/h). A turn toward the northwest is expected
later today. A northward to north-northeastward motion at a faster
forward speed is expected on Wednesday and Thursday. On the
forecast track, the center of Helene will move across the far
northwestern Caribbean Sea to near the northeastern coast of the
Yucatan Peninsula of Mexico through tonight, and then move across
the eastern Gulf of Mexico Wednesday and Thursday, potentially
reaching the Gulf coast of Florida late Thursday.
Maximum sustained winds are near 45 mph (75 km/h) with higher gusts.
Strengthening is forecast, and Helene is expected to become a
hurricane on Wednesday. Continued strengthening is anticipated
after that time, and Helene could become a major hurricane on
Thursday.
Tropical-storm-force winds extend outward up to 140 miles (220 km)
to the east of the center.
Data from NOAA buoy 42056 indicate that the minimum central pressure
is 999 mb (29.50 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
RAINFALL: Helene is expected to produce total rain accumulations of
4 to 8 inches over western Cuba and the Cayman Islands with isolated
totals around 12 inches. Over the eastern Yucatan Peninsula, 4 to 6
inches of rain are expected with isolated totals over 8 inches. This
rainfall brings a risk of considerable flooding.
Over the Southeastern U.S., Helene is expected to produce total rain
accumulations of 4 to 8 inches with isolated totals around 12
inches. This rainfall will likely result in areas of considerable
flash and urban flooding, with minor to moderate river flooding
likely, and isolated major river flooding possible.
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.
STORM SURGE: The combination of a dangerous 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…
Ochlockonee River, FL to Chassahowitzka, FL…10-15 ft
Chassahowitzka, FL to Anclote River, FL…6-10 ft
Indian Pass, FL to Ochlockonee River, FL…5-10 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
Englewood, FL to Bonita Beach, 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 2 to 4 feet above
ground level in areas of onshore winds within the warning area along
the east coast of the Yucatan Peninsula.
WIND: Hurricane conditions are possible within the watch areas in
Cuba and Mexico by early Wednesday. Hurricane conditions are
possible within the U.S. watch areas Wednesday night and early
Thursday. Tropical storm conditions are expected in the warning
areas in the Cuba and Mexico today. Tropical storm conditions are
expected in the warning area in the Lower Florida Keys beginning on
Wednesday, and are possible in the watch area in the Middle Florida
Keys beginning late Wednesday.
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 on Wednesday 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 500 PM EDT.