Official Discussion issued by the National Hurricane Center

Paulette (AL172020) DATA RELEASED: 9/12/2020 9:00:00 AM UTC

Copy of official data

Tropical Storm Paulette Discussion Number  22
NWS National Hurricane Center Miami FL       AL172020
500 AM AST Sat Sep 12 2020

Conventional satellite imagery shows that the cyclone's cloud
pattern has improved during the past several hours and that Paulette
maybe on the cusp of becoming a hurricane very soon.  An Advanced 
Technology Microwave Sounder (ATMS) overpass suggested that the 
cyclone has a much less vertical tilt and deep convective banding 
is developing in the south and east portions of Paulette.  The 
subjective and objective satellite intensity T-numbers haven't 
changed from 6 hours ago, and the initial intensity is held at 60 

The UW-CIMSS shear analysis reveals some decrease in the shear
magnitude and the upper wind pattern has become much more
diffluent.  The ECMWF/FV3 SHIPS and the large-scale models indicate
that the shear will relax soon, and Paulette should become a 
hurricane today and further strengthen to a major hurricane early 
Tuesday.  The SHIPS statistical-dynamical model indicates this 
scenario occuring earlier, Monday evening.  The official intensity 
forecast is nudged slightly higher than the previous one and is 
close to the the HFIP Corrected Consensus Approach intensity 
model.  It is also important to note that the average NHC intensity 
errors are around 10-15 kt at 48-72 h, the range at which Paulette 
will likely be nearest to Bermuda.

The initial motion is estimated to be northwestward, or 310/15 kt.  
A mid-tropospheric ridge/Bermuda high north of the cyclone should
continue to build across the western Atlantic and steer Paulette
west-northwestward for the next 36 hours.  Afterward, a turn toward 
the northwest to north-northwest with a significant increase in 
forward speed is expected early Monday and Monday evening in 
response to an approaching mid-latitude major shortwave trough.  
The track guidance suite remains tightly clustered with just some 
minor forward speed differences beyond day 3, so it's quite certain 
that Paulette will move near Bermuda early Monday, though it's a 
little too early to specify the exact closest approach.  The NHC 
track forecast is close to the previous advisory and once again is 
based on the various multi-model guidance.

Key Messages:

1. Paulette is expected to approach Bermuda as a hurricane on
Sunday and Monday.  A prolonged period of strong winds, storm surge,
and heavy rainfall on Bermuda beginning Sunday night is becoming
increasingly likely. A tropical storm warning and a hurricane
watch have been issued for the island.

2. Swells produced by Paulette are affecting portions of the
Leeward Islands and will continue to spread westward to the Greater
Antilles, the Bahamas, Bermuda, and the southeastern United States
through the weekend. These swells could cause life-threatening surf
and rip current conditions.


INIT  12/0900Z 26.8N  56.1W   60 KT  70 MPH
12H  12/1800Z 28.0N  58.0W   70 KT  80 MPH
24H  13/0600Z 29.2N  60.5W   75 KT  85 MPH
36H  13/1800Z 30.3N  62.9W   80 KT  90 MPH
48H  14/0600Z 31.8N  64.8W   85 KT 100 MPH
60H  14/1800Z 33.5N  65.2W   90 KT 105 MPH
72H  15/0600Z 35.2N  63.2W   95 KT 110 MPH
96H  16/0600Z 38.2N  56.9W   95 KT 110 MPH
120H  17/0600Z 41.5N  49.7W   80 KT  90 MPH

Forecaster Roberts