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Tropical Storm Elsa Discussion Number   3
NWS National Hurricane Center Miami FL       AL052021
500 AM AST Thu Jul 01 2021
 
The tropical cyclone's cloud pattern became a little better
organized overnight, with convective banding features becoming more
evident over the western and southwestern portions of the
circulation.  Upper-level outflow is well-defined to the west of
the system, and restricted over the eastern semicircle.  The
current intensity is set at 35 kt in agreement with Dvorak
estimates from SAB and TAFB, and just slightly above the maximum
winds from an earlier scatterometer pass, making the cyclone a
tropical storm.  Elsa is the earliest-known fifth named storm on
record for the Atlantic basin in the satellite era (1966-present),
breaking the record formerly held by Edouard on July 6, 2020.
 
The storm has been accelerating westward overnight, and the initial
motion is around 275/22 kt.  A strong subtropical ridge is situated
to the north of the storm, and this feature should steer the system
quickly to the west-northwest for the next 3 days or so. There is
significant uncertainty in the track forecast from days 3-5.  The
ECMWF model turns the cyclone northward after interacting with
Hispaniola while the other models such as the GFS, HWRF, and U.K.
Met take Elsa across western Cuba and into the southeastern Gulf of
Mexico.  The official forecast is similar to the previous one, and
within the latter suite of guidance.  However the discrepancy in
the models makes confidence in this track lower than usual.
 
Some intensification is likely for the next day or two, since Elsa
is expected to be in an environment of warm sea-surface
temperatures, fairly low vertical wind shear, and high
mid-level relative humidity.  However, the fast forward motion could
result in some decoupling of the low- and higher-level circulation
which would limit strengthening.  Also, the potential interaction
of the storm with the mountainous land masses of the Greater
Antilles later in the forecast period could disrupt the circulation
somewhat.  Therefore the official intensity forecast, like the
previous one, is quite conservative and on the lower end of the
guidance suite.
 
 
Key Messages:
 
1. Tropical storm conditions are expected beginning early Friday in
portions of the Windward and southern Leeward Islands.
 
2. Heavy rainfall from the system will move quickly across the
Windward and southern Leeward Islands, including Barbados, on
Friday.  Isolated flash flooding and mudslides are possible.
 
3. There is a risk of wind and rainfall impacts in portions of the
Virgin Islands, Puerto Rico, Hispaniola, Cuba, the Turks and Caicos
and the southeastern Bahamas through early next week.  Interests in
these areas should monitor the system's progress and updates to the
forecast.
 
4. Interests in Florida should monitor updates to the forecast for
this system, but it is too soon to determine what if any impacts
could occur there next week given the uncertainty in the long-range
forecast.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  01/0900Z  9.4N  48.8W   35 KT  40 MPH
 12H  01/1800Z 10.3N  52.0W   40 KT  45 MPH
 24H  02/0600Z 11.7N  56.7W   50 KT  60 MPH
 36H  02/1800Z 13.2N  61.8W   50 KT  60 MPH
 48H  03/0600Z 14.9N  66.9W   55 KT  65 MPH
 60H  03/1800Z 16.7N  71.2W   55 KT  65 MPH
 72H  04/0600Z 18.0N  74.5W   50 KT  60 MPH
 96H  05/0600Z 21.0N  79.5W   50 KT  60 MPH
120H  06/0600Z 24.5N  82.0W   55 KT  65 MPH
 
$$
Forecaster Pasch
 
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