Official Discussion issued by the National Hurricane Center

Laura (AL132020) DATA RELEASED: 8/21/2020 9:00:00 PM UTC

Copy of official data

Tropical Storm Laura Discussion Number   8
NWS National Hurricane Center Miami FL       AL132020
500 PM AST Fri Aug 21 2020

Corrected formatting and initial intensity

A poorly-defined convective band has become evident over the 
southeastern portion of the circulation.  However, there is little 
or no deep convection near the estimated center.  Overall, the 
system's cloud pattern still has a ragged appearance.  Dvorak 
intensity estimates range from 35 to 45 kt, and the current 
intensity is held at 40 knots based on continuity from Hurricane 
Hunter observations from earlier today.  There is a fairly 
well-defined upper-level outflow pattern at this time, but an 
upper-level trough to the west of Laura could be an impediment to 
future strengthening.  The official intensity forecast is a little 
below the intensity consensus mainly due to the influences of the 
land masses of the Greater Antilles.  At days 4-5, the intensity 
forecast is also a bit below the consensus due to uncertainties at 
these longer forecast ranges.

The center is not very easy to see, even on visible or radar 
images, but the best guess at an initial motion is 275/15 kt. The 
track forecast reasoning has not changed much from the previous 
advisory package.  Laura should move generally west-northwestward 
along the southern periphery of a subtropical ridge for about the 
next 72 hours.  Later in the forecast period, the cyclone is 
expected to turn northwestward as it begins to move around the 
western side of the ridge.  The track guidance has shifted westward 
at days 4-5 and so has the official forecast, which is mostly close 
to the model consensus, but not quite as far west as that guidance 
in the latter part of the forecast period.

Another NOAA Hurricane Hunter Aircraft is scheduled to investigate 
Laura shortly.

KEY MESSAGES:

1. Tropical storm conditions are expected across portions of the 
northern Leeward Islands, the Virgin Islands, and Puerto Rico today 
through Saturday, Tropical Storm conditions are also expected along 
the northern coasts of the Dominican Republic and Haiti from 
Saturday into Sunday.  Heavy rainfall is likely across these areas 
beginning today and could cause mudslides and flash and urban 
flooding through Sunday.

2. Tropical storm conditions are possible over portions of the 
southeastern Bahamas and the Turks and Caicos Islands on Sunday.

3. The details of the long-range track and intensity forecasts 
remain more uncertain than usual since Laura is forecast to move 
near or over Portions of the Greater Antilles through Monday.  
However, Laura could bring storm surge, rainfall, and wind impacts 
to portions of Cuba, the Bahamas, and Florida early next week and 
the northern U.S. Gulf Coast by the middle of next week.  Interests 
there should monitor the progress of Laura and updates to the 
forecast during the next few days.

FORECAST POSITIONS AND MAX WINDS

INIT  21/2100Z 17.1N  61.2W   40 KT  45 MPH
12H  22/0600Z 17.7N  63.9W   40 KT  45 MPH
24H  22/1800Z 18.6N  67.3W   45 KT  50 MPH
36H  23/0600Z 19.6N  70.7W   50 KT  60 MPH...INLAND
48H  23/1800Z 20.5N  74.3W   55 KT  65 MPH...OVER WATER
60H  24/0600Z 22.0N  77.9W   55 KT  65 MPH
72H  24/1800Z 23.5N  81.5W   55 KT  65 MPH
96H  25/1800Z 26.3N  86.5W   65 KT  75 MPH
120H  26/1800Z 29.0N  89.0W   65 KT  75 MPH

$$
FORECASTER PASCH