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Potential Tropical Cyclone SIX

Potential Tropical Cyclone Six Discussion Number   2
NWS National Hurricane Center Miami FL       AL062021
1100 PM AST Mon Aug 09 2021
The disturbance is now very near the Leeward Islands and it is 
expected to produce gusty winds and heavy rains across portions of 
those islands during the next several hours.  Satellite and radar 
data indicate that deep convection continues to gradually organize 
in curved bands across the northern half of the circulation, but 
the system still seems to lack a well-defined center.  Therefore, 
the disturbance remains a potential tropical cyclone for now.  The 
initial intensity is held at 30 kt based on Dvorak estimates from 
The system is moving west-northwestward at about 14 kt.  The
main steering feature for the system will continue to be the
subtropical ridge that is situated to its north across the central
and western Atlantic.  The flow on the south side of the ridge
should keep the depression moving relatively briskly to the
west-northwest during the next couple of days, taking it across the
Leeward Islands overnight, near or over the U.S. Virgin Islands and
Puerto Rico Tuesday and Tuesday night, and then near or over
Hispaniola on Wednesday.  Beyond that time, the storm is forecast to
gradually slow down, when it nears the southwestern portion of the
ridge, as it moves near Cuba and the Bahamas late this week.  By the
weekend, most of the models show the depression reaching a weakness
in the ridge, which will likely cause a gradual turn to the right
near the Florida Keys or southern Florida. The models are in quite
good agreement, especially during the next 3 or 4 days, and the NHC
track forecast lies near the various consensus models.  Users are
reminded that the average track errors at days 4 and 5 are 175 miles
and 200 miles, respectively.
The disturbance is currently in conducive conditions for 
intensification with the cyclone currently over fairly warm 28 C 
waters and in low wind shear conditions.  The only negative factor 
for the storm is some dry air in its vicinity.  Overall, these 
environmental factors, and the model guidance, support strengthening 
during the next 24 hours or so, but the potential land interaction 
with Puerto Rico could limit the amount of intensification.  By 
Wednesday, the potential land interaction with the mountainous 
island of Hispaniola and an increase in westerly shear should cause 
some weakening. However, the environmental conditions could become 
more favorable for strengthening again by the end of the week, which 
is the reason why the forecast shows slightly higher wind speeds at 
those time periods.  The NHC intensity forecast generally follows 
the IVCN and HCCA models, which are typically the most skillful 
aids.  It should be noted that the intensity forecast is of low 
confidence since the cyclone's future strength will be quite 
dependent on the exact track and the degree of land interaction.
1. The system is forecast to become a tropical storm as it moves
through the Leeward Islands tonight, and tropical storm conditions
are possible there.  Tropical storm conditions are expected in
portions of the U.S. Virgin Islands and Puerto Rico beginning
Tuesday afternoon, and in the Dominican Republic by Wednesday.  
Tropical storm conditions are possible in northern Haiti by late 
2. Heavy rainfall could lead to flash, urban, and small stream
flooding and potential mudslides across the U.S. Virgin Islands and
Puerto Rico. The greatest threat for flooding impacts will be across
the eastern and southeastern portions of Puerto Rico.
3. There is a risk of wind and rainfall impacts elsewhere in 
portions of Hispaniola, the Turks and Caicos, the southeastern 
Bahamas, and Cuba later this week, although the forecast is more 
uncertain than usual since the system is still in its formative 
stage. Interests in these areas should monitor the system's progress 
and updates to the forecast.
4. Interests in the remainder of the Bahamas and Florida should
monitor updates to the forecast for this system, but it is too soon
to determine what if any impacts could occur there by late this week
or this weekend given the uncertainty in the long-range forecast.
INIT  10/0300Z 15.1N  60.8W   30 KT  35 MPH...POTENTIAL TROP CYCLONE
 12H  10/1200Z 16.2N  63.1W   35 KT  40 MPH...TROPICAL CYCLONE
 24H  11/0000Z 17.5N  66.0W   45 KT  50 MPH
 36H  11/1200Z 18.7N  68.8W   40 KT  45 MPH...INLAND
 48H  12/0000Z 19.9N  71.5W   35 KT  40 MPH...INLAND
 60H  12/1200Z 20.9N  74.0W   35 KT  40 MPH...OVER WATER
 72H  13/0000Z 21.7N  76.1W   35 KT  40 MPH
 96H  14/0000Z 23.4N  79.9W   40 KT  45 MPH
120H  15/0000Z 26.1N  82.4W   45 KT  50 MPH
Forecaster Cangialosi