Official Discussion issued by the National Hurricane Center

Laura (AL132020) DATA RELEASED: 8/24/2020 3:00:00 AM UTC

Copy of official data

Tropical Storm Laura Discussion Number  17
NWS National Hurricane Center Miami FL       AL132020
1100 PM EDT Sun Aug 23 2020

Radar data from Cuba and satellite images indicate that Laura
continues to gradually become better organized.  Convection is
quite deep on the south side of the circulation, and rainfall is 
likely very heavy over portions of eastern Cuba and Jamaica.  A 
surface observation from Guantanamo Bay, Cuba, measured sustained 
winds of 52 kt with a wind gust to 63 kt a few hours ago.  Based on 
this observation and the system's improved structure, the initial 
intensity is nudged up to 55 kt.

Laura continues to move swiftly to the west-northwest on the south
side of a strong subtropical ridge, with the initial motion
estimated to be 285/18 kt. The subtropical high is expected to
expand westward during the next couple of days, and that should keep
Laura moving fairly quickly to the west-northwest near or over Cuba
through Monday and then across the south-central Gulf of Mexico on
Tuesday. The models suggest that a gradual turn to the northwest is
likely by early Wednesday as the storm nears the western side of 
the ridge, followed by a northward motion after that. The details 
of the northwest and north turn are quite important when trying to 
figure out where the core of Laura is going to make landfall.  
However, at this time there is still a notable spread in the models 
and their ensemble members, meaning that it is still unclear 
exactly where the worst weather conditions will occur.  The NHC 
track forecast is little changed from earlier and near the 
consensus aids.  This forecast shows landfall along the northern 
Gulf coast in about 3 days.

The tropical storm is expected to move very near or over the entire
island of Cuba through Monday, and the interaction with the island
should limit strengthening during that time.  However, significant
intensification is expected when the storm moves over the Gulf of
Mexico due to a combination of favorable conditions of low wind
shear, high moisture, and warm SSTs.  The NHC intensity forecast is
largely an update of the previous one and lies near the middle of
the guidance envelope.  Although not explicitly forecast, Laura
could threaten the northwestern Gulf coast near major hurricane
strength.

Users are again reminded to not to focus on the exact details of
the track or intensity forecast as the average NHC track error at
72 h is around 100 miles and the average intensity error is around
15 mph (13 kt).  In addition, winds, storm surge, and rainfall
hazards will extend far from the center.

Key Messages:

1. Tropical storm conditions are expected across much of Cuba 
through Monday. Heavy rainfall is likely across Cuba and Jamaica 
through Monday and these rains could cause mudslides and 
life-threatening flash and urban flooding.  Tropical storm 
conditions are expected in the Dry Tortugas on Monday.

2. Tropical storm conditions are possible over the Middle and Lower
Florida Keys on Monday.

3. While the details of the long-range track and intensity forecasts
remain uncertain, Laura is forecast to strengthen over the Gulf of
Mexico and there is an increasing risk of dangerous storm surge,
wind, and rainfall impacts along portions of the U.S. Gulf Coast by
the middle of the week. This could result in a prolonged period of
hazardous weather for areas that are likely to be affected by Marco.
Interests along the Gulf Coast should monitor the progress of Laura
and Marco and updates to the forecast during the next couple of 
days.


FORECAST POSITIONS AND MAX WINDS

INIT  24/0300Z 20.1N  76.6W   55 KT  65 MPH...NEAR CUBA
12H  24/1200Z 21.1N  79.4W   55 KT  65 MPH...NEAR CUBA
24H  25/0000Z 22.5N  82.6W   60 KT  70 MPH...NEAR CUBA
36H  25/1200Z 23.8N  85.7W   65 KT  75 MPH
48H  26/0000Z 25.3N  88.5W   70 KT  80 MPH
60H  26/1200Z 27.1N  90.9W   80 KT  90 MPH
72H  27/0000Z 29.2N  92.4W   90 KT 105 MPH...NEAR THE COAST
96H  28/0000Z 34.2N  90.9W   40 KT  45 MPH...INLAND
120H  29/0000Z 37.4N  83.7W   25 KT  30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Cangialosi