Official Discussion issued by the National Hurricane Center

Philippe (AL172023) DATA RELEASED: 9/29/2023 9:00:00 PM UTC

Copy of official data

Tropical Storm Philippe Discussion Number  26
NWS National Hurricane Center Miami FL       AL172023
500 PM AST Fri Sep 29 2023

Satellite imagery shows the center of Philippe has become exposed 
again due to 15-20 kt of mid-level westerly shear. Deep convection 
is generally confined to the southeast portion, with a growing band 
to the south of the center. The Air Force Hurricane Hunters 
investigated Philippe this afternoon and found the minimum pressure 
to be 1002 mb and winds to support an intensity of 45 kt. Based on 
the aircraft and ASCAT data, tropical-storm-force winds extend well 
east and southeast of the center.

Philippe is moving a little faster this afternoon, but still 
relatively slowly as it continues in a general southwest direction. 
The current track is due to its interaction with Tropical Storm Rina 
several hundred miles to its east.  Since these tropical cyclones 
are expected to continue to interact through the weekend, Philippe 
is forecast to crawl southwestward through Sunday.  After that time, 
Rina is expected to separate from Philippe as a mid-level ridge 
builds over the subtropical central Atlantic. In response, Philippe 
should turn sharply northward early next week. Recent guidance has 
shown an overall shift to the west, with the 12Z ECMWF model about 
60 n mi west of its previous run. The NHC track forecast has also 
been nudged to the west toward the various consensus models.

Although Philippe is still being affected by shear, the environment 
over the next couple of days appears to become less hostile. 
Moderate wind shear, upper-level diffluence, increasing mid-level 
humidities around the storm, and very warm SSTs should allow 
Philippe to gradually strengthen through the weekend. Beyond that 
time, the intensity forecast becomes more dependent on the future 
track. If Philippe tracks along the western side of the guidance, it 
will likely weaken due to stronger wind shear. Whereas, if the 
system tracks east of the NHC track, it could strengthen more than 
predicted due to more favorable environmental factors. The NHC 
intensity forecast is a little higher than the previous cycle in the 
short term, but is still on the low end of the guidance.


INIT  29/2100Z 18.0N  55.9W   45 KT  50 MPH
12H  30/0600Z 17.6N  56.2W   45 KT  50 MPH
24H  30/1800Z 17.3N  56.5W   50 KT  60 MPH
36H  01/0600Z 17.2N  57.0W   55 KT  65 MPH
48H  01/1800Z 17.6N  57.4W   60 KT  70 MPH
60H  02/0600Z 18.3N  58.0W   60 KT  70 MPH
72H  02/1800Z 19.5N  58.3W   60 KT  70 MPH
96H  03/1800Z 22.9N  58.7W   60 KT  70 MPH
120H  04/1800Z 26.9N  57.7W   60 KT  70 MPH

Forecaster Cangialosi