Official Discussion issued by the National Hurricane Center

Paulette (AL172020) DATA RELEASED: 9/10/2020 9:00:00 AM UTC

Copy of official data

Tropical Storm Paulette Discussion Number  14
NWS National Hurricane Center Miami FL       AL172020
500 AM AST Thu Sep 10 2020

Although Paulette's center of circulation has separated farther 
south from the cloud mass during the past several hours, the 
cyclone is still producing an area of deep convection consisting of 
-79C cold cloud tops.  Earlier scatterometer data indicated surface 
winds of 45-50 kt in this region of coldest cloud tops, so it's 
reasonable to think that those winds are still present.  Therefore, 
the initial intensity is held at 50 kt for this advisory. 

Both the ECMWF and FV3 SHIPS intensity models show the shear 
magnitude increasing to 35-40 kt today.  As a result, Paulette is 
expected to begin weakening by this evening.  Over the weekend, 
however, the shear is forecast to decrease gradually and shift from 
the southeast and become a bit more diffluent, which should allow 
for reintensification.  Several of the skilled intensity guidance, 
including the aforementioned SHIPS, and the consensus models, HCCA 
and IVCN, now show Paulette as a hurricane in 4 days, or sooner 
(COAMPS-TC).  The official intensity forecast is once again 
adjusted upward, and lies between the HCCA (a little higher) and 
the Decay SHIPS intensity guidance.

The initial motion is estimated to be west-northwestward, or
290/9 kt and Paulette should continue in this general motion 
through Friday as a mid-tropospheric ridge temporarily builds over 
the central Atlantic in response to a mid- to upper-level trough, 
extending southwestward from the Azores Islands, weakening and 
lifting northeastward.  By Saturday morning, a break in the 
aforementioned ridge develops due to a combination of mid- to 
upper-level low situated to the northwest of the cyclone and a 
mid-latitude shortwave trough moving off of the northeast U.S.  
This change in the synoptic steering pattern should cause the 
tropical cyclone to turn toward the northwest with an increase in 
forward speed.  The NHC track forecast is close to the previous 
advisory, but a little faster beyond 48 hours, and is shifted to 
the left, closer to the HCCA and TVCN consensus models at days 4 
and 5.


INIT  10/0900Z 20.9N  49.0W   50 KT  60 MPH
12H  10/1800Z 21.3N  50.4W   50 KT  60 MPH
24H  11/0600Z 21.8N  52.4W   45 KT  50 MPH
36H  11/1800Z 22.8N  54.2W   40 KT  45 MPH
48H  12/0600Z 24.1N  55.9W   40 KT  45 MPH
60H  12/1800Z 25.7N  57.5W   45 KT  50 MPH
72H  13/0600Z 27.1N  59.4W   50 KT  60 MPH
96H  14/0600Z 29.7N  63.7W   65 KT  75 MPH
120H  15/0600Z 32.0N  64.9W   75 KT  85 MPH

Forecaster Roberts