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Tropical Storm Fred Discussion Number   8
NWS National Hurricane Center Miami FL       AL062021
1100 AM AST Wed Aug 11 2021
 
Morning satellite imagery and reports from a NOAA Hurricane Hunter
aircraft indicate that the circulation of Fred has become better
defined south of the eastern Dominican Republic.  The NOAA plane
reported maximum flight-level winds of 40-45 kt, and SFMR winds of
up to 50 kt, although these were measured near the coast and the
reliability is unknown. The central pressure is near 1006 mb.
Based on these data and a dropsonde northeast of the center, the
initial intensity is increased to 40 kt.  The low-level center is 
partly exposed near the western edge of the convection, which has 
decreased in coverage since yesterday.
 
The center has been moving more westward for the past few hours.  
However, the longer term motion is 290/14.  There is no change in 
the track forecast philosophy since the previous advisory.  Fred 
should continue moving generally west-northwestward for the next 
72 h or so, followed by a turn toward the northwest as the cyclone 
nears the western periphery of the ridge. The new forecast track is 
little changed from the previous advisory and lies near the various 
consensus models.  However, some adjustments to the track may be 
necessary as the center interacts with the mountains of Hispaniola 
during the next 12-24 hours.

Fred is now in an environment of 15-20 kt of westerly vertical 
shear produced in part by an upper-level trough near the Florida 
Peninsula, and the global models suggests that moderate shear 
should persist for at least the next 48-60 h.  This, combined with 
land interaction, should cause Fred to weaken as it crosses 
Hispaniola, and then at best slowly re-intensify after it emerges 
over the water. After that time, the global models suggest the 
trough should weaken as a large upper-level anticyclone forms near 
or just southeast of Fred.  This evolution could let the shear 
decrease a little and allow a little more strengthening, 
particularly when Fred is over the Gulf of Mexico.  The new 
intensity forecast is similar to the previous forecast and follows 
the overall trend of the intensity guidance.
 
KEY MESSAGES:
 
1. Tropical storm conditions are spreading across portions of the 
Dominican Republic.  Tropical storm conditions are possible in 
northern Haiti and the southeastern Bahamas by late today, and in 
portions of Cuba by tonight.
 
2. Heavy rainfall could lead to flash, urban, and small stream 
flooding, along with possible rapid river rises and the potential 
for mudslides in the Dominican Republic. Heavy rainfall could lead 
to flash, urban, and small stream flooding, along with possible 
rapid river rises across southern Florida. 
 
3. There is a risk of wind and rainfall impacts elsewhere in 
portions of Hispaniola, the Bahamas, and Cuba during the next few 
days, although the forecast is more uncertain than usual since Fred 
is forecast to interact with Hispaniola today and tonight.  
Interests in these areas should monitor Fred's progress and updates 
to the forecast.

4. There is an increasing risk of wind and rainfall impacts in 
Florida beginning Friday night or early Saturday in the Keys and 
spreading northward through portions of the Peninsula and the 
Panhandle Saturday through Monday. Interests throughout Florida 
should monitor Fred's progress and check updates to the forecast.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  11/1500Z 18.2N  69.7W   40 KT  45 MPH
 12H  12/0000Z 19.2N  71.4W   30 KT  35 MPH...INLAND
 24H  12/1200Z 20.3N  73.7W   30 KT  35 MPH...OVER WATER
 36H  13/0000Z 21.4N  76.0W   35 KT  40 MPH
 48H  13/1200Z 22.3N  78.1W   35 KT  40 MPH
 60H  14/0000Z 23.3N  79.9W   40 KT  45 MPH
 72H  14/1200Z 24.6N  81.4W   40 KT  45 MPH
 96H  15/1200Z 27.5N  83.5W   50 KT  60 MPH
120H  16/1200Z 30.5N  85.5W   55 KT  65 MPH...INLAND
 
$$
Forecaster Beven
 
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