Official Discussion issued by the National Hurricane Center

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

Copy of official data

Tropical Storm Paulette Discussion Number  10
NWS National Hurricane Center Miami FL       AL172020
500 AM AST Wed Sep 09 2020

The 20-30 kt of southwesterly shear continues to have a significant 
impact on Paulette's inner core.  A 0615 UTC Global Precipitation 
Measurement (GPM) Microwave Imager overpass showed a severely 
sheared tropical cyclone with the exposed surface circulation 
displaced to the south of the cloud canopy.  Although the 
objective ADT and an earlier SATCON analysis yield 45 kt, The 
initial intensity is held at a generous 50 kt for this advisory in 
deference to last night's scatterometer pass showing a few 50 kt 
winds.

In addition to the moderate, persistent shear, the RAMMB/CIRA
Average Vertical Instability parameter time series analysis 
revealed a higher than normal (1995-2010) statically stable 
environment, another potential inhibiting factor.  This was further 
supported by the statistical-dynamical intensity models showing 
a rather parched mid-troposphere (less than 58%).  Therefore, 
slow weakening of Paulette is forecast during the next few days.  
Toward the end of the period, the ECMWF and FV3 SHIPS intensity 
models continue to indicate a more southerly, diffluent pattern 
which should aid in some restrengthening, and this is indicated in 
the NHC forecast.

The initial motion is estimated to be westward, or 280/7 kt. 
Paulette should turn west-northwestward later today and westward on
Thursday around the southwestern periphery of a subtropical ridge 
to the northeast of the cyclone.  A turn northwestward is predicted 
on Saturday as Paulette moves further into a growing weakness in 
the ridge over the western Atlantic.  The official forecast is an 
update of the previous one through 72 hrs, then is shifted to the 
left through day 5 to lies between the HCCA consensus and the  
the HFIP/NUOPC Project's 5EMN 133 member multi-model ensemble mean.


FORECAST POSITIONS AND MAX WINDS

INIT  09/0900Z 19.2N  45.6W   50 KT  60 MPH
12H  09/1800Z 19.7N  46.9W   50 KT  60 MPH
24H  10/0600Z 20.3N  49.0W   45 KT  50 MPH
36H  10/1800Z 20.5N  50.7W   45 KT  50 MPH
48H  11/0600Z 20.8N  52.2W   40 KT  45 MPH
60H  11/1800Z 21.4N  53.6W   40 KT  45 MPH
72H  12/0600Z 22.7N  54.9W   40 KT  45 MPH
96H  13/0600Z 25.9N  58.2W   45 KT  50 MPH
120H  14/0600Z 28.7N  61.4W   50 KT  60 MPH

$$
Forecaster Roberts