Tropical Depression Grace Advisory Number 13
NWS National Hurricane Center Miami FL AL072021
1100 AM EDT Mon Aug 16 2021
...CENTER OF GRACE JUST ABOUT TO CROSS THE BARAHONA PENINSULA OF
THE DOMINICAN REPUBLIC...
...FLASH FLOODING AND MUDSLIDES POSSIBLE ACROSS THE DOMINICAN
REPUBLIC AND HAITI TODAY...
SUMMARY OF 1100 AM EDT...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...17.7N 71.4W
ABOUT 85 MI...140 KM SE OF PORT AU PRINCE HAITI
ABOUT 430 MI...690 KM E OF MONTEGO BAY JAMAICA
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...W OR 280 DEGREES AT 15 MPH...24 KM/H
MINIMUM CENTRAL PRESSURE...1007 MB...29.74 INCHES
WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:
The government of Cuba has issued a Tropical Storm Warning for the
southern coasts of the provinces of Santiago de Cuba, Granma, Las
Tunas, and Camaguey. A Tropical Storm Watch has been issued for
the southern coasts of the provinces of Ciego de Avila, Sancti
Spiritus, Cienfuegos, and Matanzas, as well as Isla de la Juventud.
The government of the Cayman Islands has issued a Tropical Storm
Warning for the Cayman Islands.
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
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
A Tropical Storm Watch is in effect for...
* Entire coast of the Dominican Republic
* Entire coast of Haiti
* Jamaica
* Southern coast of the Cuban provinces of Ciego de Avila, Sancti
Spiritus, Cienfuegos, and Matanzas, as well as Isla de la Juventud.
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 Cuba and the Yucatan Peninsula of Mexico
should monitor the progress of Grace. Additional watches or
warnings are possible later today or tonight.
For storm information specific to your area, please monitor
products issued by your national meteorological service.
DISCUSSION AND OUTLOOK
----------------------
At 1100 AM EDT (1500 UTC), the center of Tropical Depression Grace
was located near latitude 17.7 North, longitude 71.4 West. Grace
is moving toward the west near 15 mph (24 km/h). A westward to
west-northwestward motion is expected over the next several days.
On the forecast track, the center of Grace will pass near the
southern coast of Hispaniola today and tonight, and then pass
between Jamaica, Cuba, and the Cayman Islands on Tuesday and
Wednesday.
Maximum sustained winds are near 35 mph (55 km/h) with higher gusts.
Some strengthening is forecast during the next few days, and Grace
is expected to become a tropical storm again by Tuesday.
The estimated minimum central pressure is 1007 mb (29.74 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
www.hurricanes.gov/graphics_at2.shtml?key_messages.
WIND: Tropical storm conditions are possible in the Dominican
Republic today, in Haiti today into tonight, and in Jamaica on
Tuesday. Tropical storm conditions are expected along the southern
coast of Cuba within the warning area on Tuesday, and over the
Cayman Islands beginning late Tuesday into early Wednesday.
Tropical storm conditions are possible along the southern coast of
Cuba within the watch area Tuesday night and Wednesday.
RAINFALL: Grace is expected to produce the following rainfall
amounts:
Over Haiti and the Dominican Republic...5 to 10 inches of rain with
isolated maximum totals of 15 inches are expected across the
southern terrain areas through Tuesday. This heavy rainfall may lead
to flash and urban flooding, and possible mudslides.
Over Cuba, Jamaica, and the Cayman Islands...2 to 4 inches of rain
with isolated maximum totals of 6 inches are expected through
Thursday.
SURF: Swells generated by Grace will continue to affect portions of
Hispaniola and Puerto Rico over the next day or so, and will spread
westward to Jamaica, the Cayman Islands, and the southern coast
of Cuba. These swells are likely to cause life-threatening surf
and rip current conditions. Please consult products from your local
weather office.
NEXT ADVISORY
-------------
Next intermediate advisory at 200 PM EDT.
Next complete advisory at 500 PM EDT.
$$
Forecaster Berg
Tropical Depression Grace Discussion Number 13
NWS National Hurricane Center Miami FL AL072021
1100 AM EDT Mon Aug 16 2021
Air Force Reserve and NOAA Hurricane Hunters were both able to
locate a center for Grace--probably the most well-defined center
observed over the past few days. That center now appears to be
moving onshore along the Barahona Peninsula of the Dominican
Republic as we speak. The planes measured several possible areas
of tropical-storm-force winds from the SFMR, however these
observations have not been supported by the more reliable 925-mb
flight-level winds for weaker systems, which were only as high as
38 kt, and warrant maintaining the 30-kt initial intensity.
Dropsonde data indicate that the central pressure has fallen to 1007
mb.
The aircraft fixes confirm that Grace is moving westward, or 280/13
kt. High pressure over the western Atlantic is forecast to slide
westward over the southeastern United States during the next
several days, which should keep Grace on a westward to west-
northwestward trajectory for the entire 5-day forecast period.
This scenario is agreed upon by all of the available track models,
and the new NHC track forecast has only been nudged slightly
southward from the previous forecast based on the latest consensus
aids.
Grace's intensity forecast remains complicated by interaction with
land and the possibility of some westerly shear during the forecast
period. However, the southern shift in the forecast track takes
the center of Grace more definitively over very warm 30 degrees
Celsius waters in the northwestern Caribbean Sea. Therefore,
gradual strengthening is anticipated while Grace approaches the
Yucatan coast of Mexico. Once the system reaches the Gulf of
Mexico, the shear appears to decrease, and conditions there will
likely be conducive for additional strengthening. In fact, many of
the models, including the consensus aids, bring Grace to hurricane
intensity, and the NHC intensity forecast has therefore been bumped
upward, bringing Grace very near hurricane strength by the end of
the forecast period.
Key Messages:
1. Heavy rainfall across the Dominican Republic, Haiti, Cuba,
Jamaica, and the Cayman Islands may lead to flash, urban, and small
stream flooding, with the potential for mudslides highest in Haiti
and the Dominican Republic.
2. Tropical storm conditions are possible over portions of
Hispaniola today and tonight, and over Jamaica on Tuesday.
Tropical storm conditions are expected over portions of the southern
coast of Cuba on Tuesday, spreading westward to the Cayman Islands
and other portions of the southern coast of Cuba Tuesday evening
through Wednesday morning.
3. There is a increasing risk of wind and rainfall impacts over
the Yucatan Peninsula of Mexico Wednesday night and Thursday.
Interests there areas should monitor the progress of Grace and
updates to the forecast.
FORECAST POSITIONS AND MAX WINDS
INIT 16/1500Z 17.7N 71.4W 30 KT 35 MPH
12H 17/0000Z 18.2N 73.4W 30 KT 35 MPH...S COAST OF HAITI
24H 17/1200Z 18.8N 76.2W 35 KT 40 MPH
36H 18/0000Z 19.4N 79.0W 40 KT 45 MPH
48H 18/1200Z 20.1N 82.1W 45 KT 50 MPH
60H 19/0000Z 20.9N 85.2W 50 KT 60 MPH
72H 19/1200Z 21.6N 88.4W 50 KT 60 MPH...N COAST OF YUCATAN
96H 20/1200Z 22.5N 94.0W 60 KT 70 MPH
120H 21/1200Z 23.0N 98.0W 60 KT 70 MPH...INLAND
$$
Forecaster Berg