Official Discussion issued by the National Hurricane Center

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

Copy of official data

Tropical Storm Paulette Discussion Number   9
NWS National Hurricane Center Miami FL       AL172020
1100 PM AST Tue Sep 08 2020

Microwave and satellite data suggest that vertical shear is 
weakening Paulette.  The center is near the southern side of a large 
thunderstorm cluster, with the bulk of deep convection in the 
northeastern quadrant of the cyclone.  A recent ASCAT-B pass showed 
maximum winds of 45-50 kt, a little lower than the other satellite 
estimates, and 50 kt is chosen as the initial wind speed.

With Paulette already on a weakening trend, it seems that the window 
for significant strengthening has closed.  More likely, a gradual 
decay of the storm is anticipated due to moderate or strong shear 
during the next few days.  This shear could abate by the end of the 
forecast period due to Paulette moving around the northeastern side 
of a large mid-to-upper level low, which is a common position for 
the re-intensification of a tropical cyclone after encountering the 
mid-oceanic trough.  The new forecast is lowered from the previous 
one for the first few days and then raised slightly at the longer
ranges. This is consistent with a blend of the intensity model 
consensus, leaning toward the NOAA corrected-consensus guidance at 
the end.

The storm is moving northwestward at about 8 kt.  There has been 
some convergence of the model guidance during the next few days as 
Paulette should move west-northwestward tomorrow and westward on 
Thursday around a mid-level ridge.  Thus, little change has been 
made from the previous forecast during the first 48-72h. Afterwards, 
the forecast is shifted to the north by 45-60 n mi under the 
assumption that Paulette stays coherent as a tropical cyclone and 
takes a turn to the northwest this weekend on the eastern flank of 
the aforementioned mid-to-upper level low.  The new track forecast 
is northeast of the model consensus and places less emphasis on 
models, like the 12Z ECMWF, which show Paulette staying weaker and 
missing the full influence of the low.


INIT  09/0300Z 19.2N  45.0W   50 KT  60 MPH
12H  09/1200Z 19.8N  46.2W   50 KT  60 MPH
24H  10/0000Z 20.2N  48.1W   50 KT  60 MPH
36H  10/1200Z 20.6N  50.0W   45 KT  50 MPH
48H  11/0000Z 20.8N  51.7W   45 KT  50 MPH
60H  11/1200Z 21.1N  52.9W   40 KT  45 MPH
72H  12/0000Z 21.9N  53.8W   40 KT  45 MPH
96H  13/0000Z 24.4N  55.7W   45 KT  50 MPH
120H  14/0000Z 27.5N  59.0W   55 KT  65 MPH

Forecaster Blake