Tropical Storm Philippe Discussion Number  12
NWS National Hurricane Center Miami FL       AL172023
500 AM AST Tue Sep 26 2023

West-southwesterly vertical wind shear, associated with an 
upper-level low near 26N 50W, continues to affect Philippe.  The 
low-level center of the tropical cyclone is located near the 
western edge of an area of rather disorganized deep convection.  
Some sporadic convection has been redeveloping nearer to the center 
of the system, but overall Philippe's cloud pattern remains 
disheveled in appearance and lacks banding features.  The current 
intensity estimate is kept at 45 kt in deference to the earlier 
scatterometer data.  However, subjective and objective Dvorak 
intensity estimates are somewhat lower.

The global models indicate that the vertical shear over Philippe 
is not likely to abate significantly during the forecast period, 
with upper-tropospheric westerlies dominating the flow to the north 
and northeast of the Greater Antilles through 120 hours.  Also, the 
model guidance indicates that Philippe will be encountering a 
somewhat drier low- to mid-level air mass during the next several 
days.  These environmental factors should lead to gradual weakening, 
and thus Philippe is forecast to become a depression and then a 
remnant low in 3 and 5 days, respectively.  This is in good 
agreement with the corrected consensus intensity model, HCCA, 
guidance.

Over the past day or so, the storm has been moving westward to 
west-northwestward and the current motion estimate is 285/11 kt.  A 
weak mid-level ridge is expected to be maintained to the north 
of Philippe for the next few days, which is likely to keep steering 
the cyclone on a generally west-northwestward track.  Later in the 
forecast period, Philippe should be a weaker, shallower system and 
move on a mainly westward heading, following the low-level easterly 
flow.  The official track forecast is similar to the previous NHC 
track, only a little to the left and slightly faster in 3-5 days.  
This lies between the model consensus and the latest ECMWF 
prediction, which is even faster and a little farther south.


FORECAST POSITIONS AND MAX WINDS

INIT  26/0900Z 17.7N  49.0W   45 KT  50 MPH
12H  26/1800Z 18.2N  50.4W   45 KT  50 MPH
24H  27/0600Z 19.1N  52.1W   45 KT  50 MPH
36H  27/1800Z 20.1N  53.9W   45 KT  50 MPH
48H  28/0600Z 21.0N  55.4W   40 KT  45 MPH
60H  28/1800Z 21.6N  56.9W   40 KT  45 MPH
72H  29/0600Z 21.9N  58.2W   35 KT  40 MPH
96H  30/0600Z 21.8N  60.9W   30 KT  35 MPH
120H  01/0600Z 21.8N  63.6W   25 KT  30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Pasch