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Tropical Storm Ida Advisory Number 4
NWS National Hurricane Center Miami FL AL092021
500 AM EDT Fri Aug 27 2021
...IDA STRENGTHENS AS THE CENTER PASSES THROUGH THE CAYMAN
...AIR FORCE RESERVE AND NOAA HURRICANE HUNTER AIRCRAFT ENROUTE TO
INVESTIGATE THE STORM...
SUMMARY OF 500 AM EDT...0900 UTC...INFORMATION
ABOUT 50 MI...80 KM NNW OF GRAND CAYMAN
ABOUT 145 MI...230 KM SE OF THE ISLE OF YOUTH
MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H
PRESENT MOVEMENT...NW OR 320 DEGREES AT 15 MPH...24 KM/H
MINIMUM CENTRAL PRESSURE...1001 MB...29.56 INCHES
WATCHES AND WARNINGS
CHANGES WITH THIS ADVISORY:
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Storm Surge Watch is in effect for...
* Sabine Pass to Alabama/Florida border
* Vermilion Bay, Lake Borgne, Lake Pontchartrain, Lake Maurepas, and
A Hurricane Watch is in effect for...
* Cameron, Louisiana to the Mississippi/Alabama border
* Lake Pontchartrain, Lake Maurepas, and Metropolitan New Orleans
A Tropical Storm Warning is in effect for...
* Cayman Islands
* Cuban provinces of Matanzas, Mayabeque, Havana, Artemisa, Pinar
del Rio, and the Isle of Youth
A Tropical Storm Watch is in effect for...
* Mississippi/Alabama border to the Alabama/Florida border.
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
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
A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area within 36 hours.
A Tropical Storm Watch means that tropical storm conditions are
possible within the watch area, generally within 48 hours.
Interests elsewhere in central and western Cuba, in the northern
Yucatan Peninsula, and elsewhere along the northern U.S. Gulf coast
should monitor the progress of this system. Hurricane warnings
will likely be required for portions of the northern Gulf coast
later today. Interests in the Dry Tortugas should also monitor the
progress of Ida.
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 500 AM EDT (0900 UTC), the center of Tropical Storm Ida was
located by weather radar on Grand Cayman near latitude 20.0 North,
longitude 81.4 West. Ida is moving toward the northwest near 15 mph
(24 km/h) and this general motion should continue over the
next few days. On the forecast track, the center of Ida will
move away from the Cayman Islands this morning, pass near or over
the Isle of Youth and western Cuba later today, and over the
southeastern and central Gulf of Mexico tonight and Saturday.
The system is forecast to approach the U.S. northern Gulf coast on
Maximum sustained winds have increased to near 45 mph (75 km/h)
with higher gusts, and additional steady to rapid strengthening is
expected during the next few days. Ida is forecast to become a
hurricane over the southeastern Gulf of Mexico in a day or two,
and to be at or near major hurricane strength when it approaches
the northern Gulf coast.
Tropical-storm-force winds extend outward up to 80 miles (130 km)
from the center.
The estimated minimum central pressure is 1001 mb (29.56 inches).
Grand Cayman Island recently reported a pressure of 1003 mb (29.62
HAZARDS AFFECTING LAND
Key messages for Tropical Storm Ida can be found in the
Tropical Cyclone Discussion under AWIPS header MIATCDAT4, WMO
header WTNT44 KNHC, and on the web at
STORM SURGE: A dangerous storm surge will raise water levels by
as much as 2 to 4 feet above normal tide levels in areas of onshore
winds along the immediate coast of the Isle of Youth and near and to
the east of where the center crosses the coast of western Cuba.
Near the coast, the surge will be accompanied by large and
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...
Morgan City, LA to Ocean Springs, MS including Lake Borgne...7-11 ft
Rockefeller Wildlife Refuge, LA to Morgan City, LA including
Vermilion Bay...4-7 ft
Ocean Springs, MS to MS/AL border...4-7 ft
MS/AL border to AL/FL border including Mobile Bay...3-5 ft
Lake Pontchartrain...3-5 ft
Lake Maurepas...2-4 ft
Sabine Pass to Rockefeller Wildlife Refuge, LA...2-4 ft
The deepest water will occur along the immediate coast near and to
the east of the landfall location, where the surge will be
accompanied by large and dangerous waves. Surge-related flooding
depends on the relative timing of the surge and the tidal cycle,
and can vary greatly over short distances. For information
specific to your area, please see products issued by your local
National Weather Service forecast office.
WIND: Tropical storm conditions are expected in the Cayman Islands
this morning, and are expected to reach the Isle of Youth and
portions of western Cuba in the warning area later today. Hurricane
conditions are possible in the hurricane watch area along the
northern Gulf coast late Saturday night or Sunday and tropical storm
conditions are possible in the watch area late Saturday night or
RAINFALL: Ida is expected to produce total rainfall accumulations
of 6 to 10 inches with maximum totals of 15 inches across Jamaica.
Rainfall totals of 8 to 12 inches with isolated maximum amounts of
20 inches are expected across the Cayman Islands and western Cuba,
including the Isle of Youth. These rainfall amounts may produce
life-threatening flash floods and mudslides.
As Ida approaches the central Gulf Coast Sunday afternoon, total
rainfall accumulations of 8 to 16 inches with isolated maximum
amounts of 20 inches are possible from southeast Louisiana to
coastal Mississippi and Alabama through Monday morning. Ida is
forecast to turn northeast as it moves inland later Monday with
rainfall totals of 4 to 8 inches possible across southern and
central Mississippi. This is likely to result in considerable flash,
urban, small stream, and riverine flooding.
SURF: Swells generated by this system will affect Jamaica, the
Cayman Islands and Cuba tonight and Friday. Swells will begin
reaching portions of the northern Gulf coast Saturday night or
early Sunday. These swells are likely to cause life-threatening
surf and rip current conditions. Please consult products from your
local weather office.
Next intermediate advisory at 800 AM EDT.
Next complete advisory at 1100 AM EDT.