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Tropical Storm Philippe Discussion Number  33
NWS National Hurricane Center Miami FL       AL172023
1100 AM AST Sun Oct 01 2023

Philippe is not a well organized tropical cyclone at this time, 
with any of the associated deep convection about a degree southeast 
of the center due to persistent northwesterly shear.  Satellite 
intensity estimates are about the same as before, so the initial 
wind speed is held 45 kt on this advisory.  A scatterometer pass 
just received also supports that value.  
 
The storm appears to be moving westward this morning, judging from 
fixes on the visible imagery.  Weak mid-level ridging is forecast to 
build east of the tropical cyclone soon, which probably will steer 
Philippe toward the west-northwest or northwest later today, and 
eventually northward as it moves into the subtropics.  The 
short-term forecast steering is extremely challenging due to the 
changing depth of associated deep convection, the cyclone vortex 
strength, and the related steering flow.  Regardless, it is clear 
that the risk to the northern Leeward Islands has increased, and the 
new forecast is adjusted west of the previous one, which 
necessitated the tropical storm watches.  Further westward shifts 
and other watches/warnings are possible later today since Philippe 
has not been a well-behaved system in such a complex steering flow.

Strong shear should continue near Philippe for the next day or so, 
leading to little overall change in strength during that time.  A 
gradual lessening of the shear is anticipated by Tuesday, but model 
guidance is in poor agreement on whether the shear will be low 
enough for significant strengthening, like many of the regional 
hurricane models suggest, or if Philippe stays sheared like the 
ECMWF solution.  For now, the forecast takes the middle of the road 
in the guidance, leading to little change from the last NHC 
prediction.

 
KEY MESSAGES:
 
1. Tropical storm conditions are possible across portions of the 
northern Leeward Islands Monday and Monday night while Philippe 
passes near or just northeast of the area, and a Tropical Storm 
Watch has been issued for Antigua and Barbuda.  Interests elsewhere 
in the northern Leeward Islands should continue to monitor this 
system as additional watches or warnings could be required later 
today or tonight.

2. Heavy rainfall from Philippe could produce isolated to scattered 
flash flooding, particularly across Barbuda and Antigua, through 
Tuesday.

 
FORECAST POSITIONS AND MAX WINDS
 
INIT  01/1500Z 16.1N  58.7W   45 KT  50 MPH
 12H  02/0000Z 16.5N  59.5W   45 KT  50 MPH
 24H  02/1200Z 17.1N  60.5W   45 KT  50 MPH
 36H  03/0000Z 17.9N  61.3W   50 KT  60 MPH
 48H  03/1200Z 19.0N  62.1W   50 KT  60 MPH
 60H  04/0000Z 20.3N  62.3W   50 KT  60 MPH
 72H  04/1200Z 22.0N  62.3W   55 KT  65 MPH
 96H  05/1200Z 25.8N  61.8W   65 KT  75 MPH
120H  06/1200Z 29.5N  59.0W   75 KT  85 MPH
 
$$
Forecaster Blake
 
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