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Tropical Storm Philippe Discussion Number  37
NWS National Hurricane Center Miami FL       AL172023
1100 AM AST Mon Oct 02 2023
 
The center of Philippe has become exposed this morning with
convection and heavy rainfall displaced to the south and southeast
of the center as high northwesterly vertical wind shear persists.
The initial intensity is held steady at 45 kt for this advisory,
consistent with SFMR data from the Air Force Reserve reconnaissance
aircraft mission showing a large area of 40-45 surface winds.
 
Center fixes and 1-min visible imagery during the morning indicate
that Philippe is moving erratically to the west-northwest (300
degrees) at 6 kt.  The short-term part of track forecast is adjusted
westward to match recent satellite trends, which necessitates the
Tropical Storm Warning for Barbuda.  After passing close to that
island, Philippe is forecast to move northwest to north-northwest
around the southwestern portion of a mid-level ridge over the
subtropical Atlantic during the next couple of days. Around
mid-week, Philippe should turn northward between the aforementioned
ridge and a mid- to upper-level trough over the southwestern
Atlantic.  Beyond 96 hours, track uncertainty increases as to
whether the ridge or trough will dominate, which is also partially
connected to how strong Philippe becomes.  Stronger solutions take
the system on a more east-northeastward track at longer range while
weaker solutions take the system more northward. Overall, the track
forecast for this advisory was adjusted farther west than the
previous advisory, after considering the latest ECMWF and ensemble
aids.
 
Strong northwesterly vertical wind shear is expected to prevent
significant strengthening in the short term. In a couple of days,
Philippe is expected to encounter a more favorable upper-level wind
pattern as it moves northward over the Atlantic. This could allow
for steady strengthening, and much of the guidance predicts that
Philippe will become a hurricane in 3 to 4 days.  The intensity
forecast is consistent with the consensus aids, although the 
uncertainty is pretty high at long range given how Philippe has so 
far refused to intensify for days now.
 
 
KEY MESSAGES:
 
1. Tropical storm conditions are expected across Barbuda and
possible across Antigua beginning this evening while Philippe passes
near or just northeast of the area.  Interests elsewhere in the
northern Leeward Islands should continue to monitor this system.
 
2. Heavy rainfall from Philippe could produce isolated to scattered
flash flooding over the northern Leeward Islands, particularly
across Barbuda and Antigua, through Tuesday.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  02/1500Z 17.1N  60.7W   45 KT  50 MPH
 12H  03/0000Z 17.8N  61.5W   45 KT  50 MPH
 24H  03/1200Z 18.9N  62.0W   50 KT  60 MPH
 36H  04/0000Z 20.2N  62.4W   50 KT  60 MPH
 48H  04/1200Z 21.8N  62.7W   50 KT  60 MPH
 60H  05/0000Z 23.5N  62.8W   55 KT  65 MPH
 72H  05/1200Z 25.3N  62.9W   60 KT  70 MPH
 96H  06/1200Z 29.2N  61.5W   70 KT  80 MPH
120H  07/1200Z 32.5N  59.5W   75 KT  85 MPH
 
$$
Forecaster Blake/Stevenson
 
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