Official Discussion issued by the National Hurricane Center

Philippe (AL172023) DATA RELEASED: 9/28/2023 3:00:00 PM UTC

Copy of official data

Tropical Storm Philippe Discussion Number  21
NWS National Hurricane Center Miami FL       AL172023
1100 AM AST Thu Sep 28 2023

Philippe remains a very disorganized and elongated storm.
Geostationary and microwave satellite images show a low-level
circulation center well to the west of the mid-level center, where
most of the deep convection is currently concentrated.  The
estimated center position shown in this advisory is roughly midway
between those features, however confidence is very low on the
storm's position. In fact, it is possible that Philippe no longer
has a well-defined center. The initial intensity is held at 45 kt,
which is near the high end of the satellite intensity estimates.

The initial motion is highly uncertain since the storm is elongated 
and confidence in the initial position is very low.  The track 
forecast is challenging, in part due to Philippe's close proximity 
to newly formed Tropical Storm Rina.  In the short term, a slow 
southwestward motion seems likely as Philippe moves in weak steering 
currents between a mid- to upper-level trough to its northeast and 
Rina to its east-southeast.  By late in the weekend, a mid-level 
ridge is anticipated to build over the subtropical central Atlantic, 
and that feature should cause Philippe to turn sharply northward 
east of the northern Leeward Islands.  The NHC track forecast has 
been adjusted to the south for the first couple of days, but lies to 
the east of the previous forecast at days 4 and 5.  This prediction 
is closest to the ECMWF model.

The environmental conditions for Philippe no longer seem unfavorable
given its expected to track to the east of the islands and not
within a region of strong shear.  Therefore, the NHC intensity
forecast has been adjusted upward and generally shows little change
in strength during the next several days.  This prediction still
lies near the low end of the model guidance, however, so future
advisories might show a higher intensity forecast if the guidance


INIT  28/1500Z 18.6N  54.6W   45 KT  50 MPH
12H  29/0000Z 18.7N  55.1W   45 KT  50 MPH
24H  29/1200Z 18.6N  55.6W   45 KT  50 MPH
36H  30/0000Z 18.4N  56.1W   45 KT  50 MPH
48H  30/1200Z 18.0N  56.7W   45 KT  50 MPH
60H  01/0000Z 17.6N  57.2W   45 KT  50 MPH
72H  01/1200Z 17.3N  57.5W   45 KT  50 MPH
96H  02/1200Z 17.7N  58.2W   45 KT  50 MPH
120H  03/1200Z 20.0N  58.9W   40 KT  45 MPH

Forecaster Cangialosi/A Reinhart