Official Discussion issued by the National Hurricane Center

Paulette (AL172020) DATA RELEASED: 9/10/2020 3:00:00 PM UTC

Copy of official data

Tropical Storm Paulette Discussion Number  15
NWS National Hurricane Center Miami FL       AL172020
1100 AM AST Thu Sep 10 2020

The highest winds in a recent scatterometer pass have decreased a 
little since last evening, and they remain embedded within deep 
convection which is displaced to the north of the center of 
circulation.  Paulette's intensity is estimated to have decreased 
to 45 kt based on this ASCAT pass and Dvorak CI numbers of 3.0/45 
kt from both TAFB and SAB.  

The sheared convection has been tugging Paulette's center northward 
at times, causing wobbles in the estimated longer-term 
west-northwestward motion of 295/9 kt.  For the next 4 days or so, 
fluctuations in the strength of the subtropical ridge to the north 
of Paulette will cause the cyclone's trajectory to vary between 
west-northwest and northwest, with a peak in forward speed around 
day 3.  At the end of the forecast period, a mid-latitude trough is 
expected to move across the northeastern United States, with a 
mid-tropospheric high becoming established over the central 
Atlantic.  This should allow Paulette to begin to recurve over the 
western Atlantic, turning northward by day 5.  The only notable 
change in the track guidance on this cycle was a slight westward 
shift among some of the models on days 4 and 5, and the NHC track 
forecast follows suit, lying close to the HFIP Corrected Consensus 
(HCCA) aid.

Southwesterly shear has increased over the cyclone as expected, with 
the latest UW-CIMSS analysis now between 35 and 40 kt.  SHIPS 
diagnoses suggest that the shear over Paulette should peak in about 
12 hours, thus a little more weakening is anticipated over the next 
day or so.  The shear is then forecast to gradually abate, and both 
the GFS and ECMWF versions of the SHIPS guidance show the shear 
magnitudes decreasing to 10 kt or less in 3-4 days.  This more 
favorable environment, combined with a more unstable air mass and 
sea surface temperatures exceeding 29 degrees Celsius, are expected 
to allow Paulette to restrengthen and become a hurricane as it 
moves in the vicinity of Bermuda.  The new NHC intensity forecast 
has been raised a bit between days 2 and 4 compared to the previous 
prediction, although it still lies below the intensity consensus, 
IVCN, and the HCCA solutions.  Therefore, additional upward 
adjustments to the forecast intensity may be required later today.


INIT  10/1500Z 21.5N  49.1W   45 KT  50 MPH
12H  11/0000Z 21.8N  50.7W   45 KT  50 MPH
24H  11/1200Z 22.6N  52.6W   40 KT  45 MPH
36H  12/0000Z 23.8N  54.4W   40 KT  45 MPH
48H  12/1200Z 25.4N  56.3W   45 KT  50 MPH
60H  13/0000Z 26.9N  58.4W   50 KT  60 MPH
72H  13/1200Z 28.0N  61.0W   60 KT  70 MPH
96H  14/1200Z 30.0N  65.0W   70 KT  80 MPH
120H  15/1200Z 32.5N  65.0W   75 KT  85 MPH

Forecaster Berg