[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT42 KNHC 282047
TCDAT2

Tropical Storm Philippe Discussion Number  22
NWS National Hurricane Center Miami FL       AL172023
500 PM AST Thu Sep 28 2023

Philippe remains poorly organized.  Visible satellite images
indicate that the circulation is elongated from east to west and
appears to have multiple centers along a trough axis.  The center
position listed in the advisory seems to be the main center and
there is some deep convection on its east and southeast sides.
Philippe barely meets the criteria needed for a tropical cyclone as
it has lost some organization today.  The initial intensity is
lowered to 40 kt, which is near the high end of the latest satellite
intensity estimates.

The initial motion is highly uncertain since the storm is elongated
and confidence in the initial position remains low.  The track
forecast is challenging, in part due to Philippe's close proximity
to Tropical Storm Rina.  During the next few days, Philippe will
likely move slowly southwestward as it rotates around Rina
currently to its east.  By late in the weekend, however, a sharp
northward turn is expected when a mid-level ridge becomes
established over the central subtropical Atlantic.  There remains a
very large east-west spread in the models, and disagreements on
where Philippe makes its northward turn.  The GFS is the right-most
model while the ECMWF remains the model farthest west.  The NHC
track forecast is little changed from the previous one and remains
closest to the ECMWF model, which has been performing best so far
for this storm.

The observed weakening of the system today appears to be related to
its interaction with Rina and some environmental dry air.  Since
these factors are expected to persist, some additional weakening is
forecast during the next day or so, and it is possible that Philippe
dissipates sometime during the next couple of days.  However, if the
storm does survive, environmental conditions are expected to become
a little more favorable when Philippe and Rina become more
separated later in the forecast period.  There is a huge spread in
the intensity models with HWRF, HMON, and the GFS showing Philippe
becoming a significant hurricane while the HAFS-A and HAFS-B models
show gradual weakening.  The NHC intensity forecast is a little
lower than the previous one in the short term, but is otherwise
unchanged and closer to the low end of the model guidance.


FORECAST POSITIONS AND MAX WINDS

INIT  28/2100Z 18.9N  55.1W   40 KT  45 MPH
 12H  29/0600Z 18.9N  55.5W   35 KT  40 MPH
 24H  29/1800Z 18.7N  55.9W   35 KT  40 MPH
 36H  30/0600Z 18.3N  56.2W   40 KT  45 MPH
 48H  30/1800Z 17.9N  56.4W   45 KT  50 MPH
 60H  01/0600Z 17.5N  57.0W   45 KT  50 MPH
 72H  01/1800Z 17.0N  57.6W   45 KT  50 MPH
 96H  02/1800Z 18.6N  58.6W   45 KT  50 MPH
120H  03/1800Z 20.6N  59.1W   40 KT  45 MPH

$$
Forecaster Cangialosi
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