Tropical Storm Philippe Forecast Discussion Number 41

By | October 3, 2023

WTNT42 KNHC 031449

Tropical Storm Philippe Discussion Number  41
NWS National Hurricane Center Miami FL       AL172023
1100 AM AST Tue Oct 03 2023

Philippe's center has become exposed to the northwest of the deep
convection, and visible satellite images from this morning suggest 
that it has lost definition.  This is confirmed by the crew from an 
ongoing Air Force Reserve Hurricane Hunter aircraft, which 
indicated a center uncertainty of 10 n mi.  The plane has only 
measured a peak 850-mb flight-level wind of 41 kt and SFMR winds of 
35-40 kt mainly within the southeastern quadrant over the waters 
between the northern Leeward Islands.  Dropsonde data also indicate 
the pressure has risen to 1004 mb.  Based on these data, Philippe's 
initial intensity is set at 40 kt.  

Philippe has sped up a bit, although it has not yet begun to turn
to right.  The current motion is barely northwestward (305 degrees)
at 9 kt, with the center now passing just to the northeast of 
Anegada Island in the British Virgin Islands.  The track guidance 
insists that Philippe will turn toward the north-northwest later 
today as it moves around the western periphery of a mid-level high 
over the central Atlantic.  However, the shallow, sheared structure 
of the cyclone may cause it to remain on the western side of the 
guidance envelope in the short term, potentially delaying any 
northward turn.  The guidance is in good agreement that the 
northward turn will eventually occur, but then there are significant 
speed differences as the storm moves across the western Atlantic.  
Primarily due to the storm's resistance to begin turning, the new 
NHC track forecast has been shifted about 45-50 n mi to the west of 
the previous prediction, but it lies very close to the latest TVCA 
and HCCA consensus aids.  Except for HWRF and HMON (which turn 
Philippe to the east), the rest of the guidance is in more agreement 
that the storm may approach Atlantic Canada in about 5 days.

Moderate to strong shear is expected to persist over Philippe for 
awhile.  Therefore, little change in strength is expected during 
the next day or two.  The upper-level environment may become a 
little more conducive for strengthening when Philippe moves 
northward over the western Atlantic, but confidence in that 
occurring is still quite low.  The NHC intensity forecast continues 
to show some modest strengthening and is close to the HCCA 
consensus aid.  Global models fields, as well as phase-space 
diagrams, indicate that Philippe could acquire frontal features as 
it is approaching Atlantic Canada, and the NHC forecast therefore 
shows it becoming post-tropical by day 5.


1. Tropical storm conditions are expected to continue on Anguilla 
and are possible on the British Virgin Islands through today. 
Strong gusty winds are also likely elsewhere in the Leeward Islands 

2. Heavy rainfall from Philippe is expected to produce scattered 
flash flooding across portions of the northern Leeward Islands and 
the British Virgin Islands into early Wednesday.


INIT  03/1500Z 18.9N  63.9W   40 KT  45 MPH
 12H  04/0000Z 19.8N  64.4W   40 KT  45 MPH
 24H  04/1200Z 21.2N  65.0W   40 KT  45 MPH
 36H  05/0000Z 22.9N  65.4W   40 KT  45 MPH
 48H  05/1200Z 24.8N  65.6W   45 KT  50 MPH
 60H  06/0000Z 27.3N  65.2W   45 KT  50 MPH
 72H  06/1200Z 30.1N  64.4W   50 KT  60 MPH
 96H  07/1200Z 35.5N  63.3W   55 KT  65 MPH
120H  08/1200Z 41.7N  63.0W   55 KT  65 MPH...POST-TROP/EXTRATROP

Forecaster Berg

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