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Tropical Storm Grace Intermediate Advisory Number 18A
NWS National Hurricane Center Miami FL AL072021
800 PM EDT Tue Aug 17 2021
...NOAA AND AIR FORCE RECONNAISSANCE AIRCRAFT FIND THE CENTER OF
GRACE JUST WEST OF JAMAICA...
...HEAVY RAINFALL AND FLASH FLOOD THREAT CONTINUES IN JAMAICA...
SUMMARY OF 800 PM EDT...0000 UTC...INFORMATION
ABOUT 50 MI...80 KM W OF MONTEGO BAY JAMAICA
ABOUT 185 MI...295 KM ESE OF GRAND CAYMAN
MAXIMUM SUSTAINED WINDS...60 MPH...95 KM/H
PRESENT MOVEMENT...W OR 280 DEGREES AT 15 MPH...24 KM/H
MINIMUM CENTRAL PRESSURE...1002 MB...29.59 INCHES
WATCHES AND WARNINGS
CHANGES WITH THIS ADVISORY:
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Hurricane Warning is in effect for...
* Yucatan Peninsula of Mexico from Cancun to Punta Herrero,
A Hurricane Watch is in effect for...
* Cayman Islands
A Tropical Storm Warning is in effect for...
* Southern coast of the Cuban provinces of Santiago de Cuba, Granma,
Las Tunas, and Camaguey
* Cayman Islands
* Yucatan Peninsula of Mexico from north of Cancun to Cabo Catoche
* Yucatan Peninsula of Mexico from south of Punta Herrero to Puerto
A Tropical Storm Watch is in effect for...
* Southern coast of the Cuban provinces of Ciego de Avila, Sancti
Spiritus, Cienfuegos, Matanzas, and Pinar del Rio, as well as Isla
de la Juventud.
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 Hurricane Watch means that hurricane conditions are possible
within the watch area.
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.
Interests elsewhere in the Yucatan Peninsula of Mexico should
monitor the progress of Grace.
Additional watches or warnings may be required tonight.
For storm information specific to your area, please monitor
products issued by your national meteorological service.
DISCUSSION AND OUTLOOK
At 800 PM EDT (0000 UTC), the center of Tropical Storm Grace was
located just west of the western tip of Jamaica near latitude
18.3 North, longitude 78.6 West. Grace is moving toward the west
near 15 mph (24 km/h). A general westward to west-northwestward
motion is expected for the next several days. On the forecast
track, the center of Grace will move away from the western coast
of Jamaica this evening. Grace is forecast to move near or over the
Cayman Islands late tonight and early Wednesday, and then approach
the Yucatan peninsula of Mexico late Wednesday or early Thursday.
Reports from NOAA and Air Force Reserve Hurricane Hunter aircraft
indicate that the maximum sustained winds have increased to near
60 mph (95 km/h) with higher gusts. Grace is forecast to
strengthen into a hurricane on Wednesday, with some additional
strengthening possible prior to the center reaching the Yucatan
Tropical-storm-force winds extend outward up to 80 miles (130 km)
from the center. A sustained wind of 40 mph (65 km/h) and a gust
to 52 mph (83 km/h) was recently reported at Kingston, Jamaica.
The latest minimum central pressure reported by an Air Force
Reserve Hurricane Hunter aircraft is 1002 mb (29.59 inches).
HAZARDS AFFECTING LAND
Key messages for Grace can be found in the Tropical Cyclone
Discussion under AWIPS header MIATCDAT2, WMO header WTNT42 KNHC
and on the web at
WIND: Tropical storm conditions are expected to continue over
portions of Jamaica through early tonight. Tropical storm
conditions are expected along a portion of the southern coast of
Cuba within the warning area through early tonight, and over the
Cayman Islands beginning tonight and into early Wednesday. Hurricane
conditions are possible in the Cayman Islands by early Wednesday.
Tropical storm conditions are possible along the southern coast of
Cuba within the watch area tonight and Wednesday. Hurricane
conditions are expected within the warning area in the Yucatan
Peninsula of Mexico on Wednesday night with tropical storm
conditions beginning as early as Wednesday evening.
RAINFALL: The system is expected to produce the following rainfall
Over Haiti...an additional 1 to 2 inches of rain with isolated
maximum totals of 15 inches are expected across the southern terrain
areas today. This heavy rainfall will likely cause flash and
urban flooding, along with possible mudslides.
Over far southern Cuba...and additional 2 to 4 inches of rain.
Additional heavy rainfall could lead to flash and urban
flooding, along with possible mudslides.
Over Jamaica, the Cayman Islands, and portions of the Yucatan
Peninsula....3 to 6 inches of rain with isolated maximum totals of
10 inches are expected through Thursday. This heavy rainfall could
lead to flash and urban flooding.
STORM SURGE: A storm surge could raise water levels as high as 1 to
3 ft above normal tide levels in portions of the Cayman Islands.
A dangerous storm surge will raise water levels by as much as 3-5
feet above normal tide levels along the immediate coast near and to
the north of where the center makes landfall in the northeastern
Yucatan Peninsula late Wednesday or early Thursday. Near the
coast, the surge will be accompanied by large and destructive waves.
SURF: Swells generated by Grace will spread westward from Jamaica
to the Cayman Islands, the southern coast of Cuba, and the
Yucatan Peninsula of Mexico. These swells are likely to cause
life-threatening surf and rip current conditions. Please consult
products from your local weather office.
Next complete advisory at 1100 PM EDT.