Tropical Storm GRACE Advisory 8月16日

ZCZC MIATCDAT2 ALL
TTAA00 KNHC DDHHMM

Tropical Depression Grace Discussion Number  10
NWS National Hurricane Center Miami FL       AL072021
500 PM AST Sun Aug 15 2021

An earlier ASCAT pass over Grace suggested that the maximum winds
were 25-30 kt and this has been confirmed by observations from a
NOAA Hurricane Hunter aircraft.  Aircraft and scatterometer data
also suggest that the circulation is elongated and disorganized.
Based on these data, the system is being downgraded to a 30-kt
depression at this time.  Since the system is below storm strength
and is passing by Puerto Rico, the Tropical Storm Warnings for
Puerto Rico and the U.S. Virgin Islands have been discontinued.  The
island of Hispaniola is kept under a Tropical Storm Watch given the
possibility that the system could restrengthen tonight or tomorrow
morning before moving over land. Most of the reliable guidance
shows little change in strength over the next 2-3 days.  This seems
reasonable since the circulation will be interacting with the
mountainous land mass of Hispaniola and Cuba for the next 72 hours.
The official intensity forecast is near or a little above the DSHIPS
and LGEM guidance during that time.  Some restrengthening is
possible later in the forecast period when the system is expected to
move over the Gulf of Mexico. However, the global models are not
very bullish on intensification in 4-5 days, perhaps due to drier
air.

The system has moved mainly westward today, but the track models
are generally in agreement on a west-northwestward motion over the
forecast period.  This is consistent with a well-defined mid-level
ridge staying in place over the southwestern Atlantic and across
Florida during this week.  The official track forecast has been
shifted a little south of the previous one, following the
multi-model consensus.

Key Messages:

1. Heavy rainfall could lead to flash and urban flooding over the
Virgin Islands.  Across Puerto Rico, the Dominican Republic and
Haiti, heavy rainfall may lead to flash, urban and small stream
flooding, along with the potential for mudslides.

2. Tropical storm conditions are possible over portions of
Hispaniola Monday and Monday night.

3. There is a risk of some wind and rainfall impacts across the
Turks and Caicos Islands, the Bahamas, Cuba, and Florida, but
forecast uncertainty is much higher than usual. Interests in those
areas should monitor the progress of Grace and updates to the
forecast.

FORECAST POSITIONS AND MAX WINDS

INIT  15/2100Z 17.0N  67.3W   30 KT  35 MPH
 12H  16/0600Z 17.6N  68.8W   30 KT  35 MPH
 24H  16/1800Z 18.2N  71.0W   30 KT  35 MPH...INLAND
 36H  17/0600Z 19.2N  73.2W   30 KT  35 MPH...OVER WATER
 48H  17/1800Z 20.2N  75.8W   30 KT  35 MPH...INLAND
 60H  18/0600Z 21.0N  78.7W   30 KT  35 MPH...OVER WATER
 72H  18/1800Z 22.1N  81.8W   30 KT  35 MPH
 96H  19/1800Z 24.0N  87.0W   35 KT  40 MPH
120H  20/1800Z 25.0N  91.0W   45 KT  50 MPH

$$
Forecaster Pasch