[Tropical] Tropical Cyclone Discussion

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WTNT42 KNHC 232040
TCDAT2

Tropical Storm Philippe Discussion Number   2
NWS National Hurricane Center Miami FL       AL172023
500 PM AST Sat Sep 23 2023

Overall, the structure of the cyclone hasn't changed significantly
since this morning. Its low-level center is still displaced west of
most of the associated deep convection. That said, satellite
intensity estimates are generally a little higher than they were
about 6 hours ago, ranging from about 30 to 35 kt. The intensity is
set at 35 kt, in best agreement with the latest subjective TAFB
Dvorak estimate and the objective UW-CIMSS DMINT and SATCON, making
the system Tropical Storm Philippe.

Philippe is expected to maintain its general structure for the next
couple of days, which should prevent it from substantially
strengthening. While the intensity guidance is generally slightly
higher than 6 h ago, the dynamical models remain in generally good
agreement on the intensity forecast for the next few days. Beyond 72
h, Philippe will approach a mid- to upper-level trough, which could
result in an increase of both upper-level difluence and deep-layer
shear. Slight additional intensification is possible at that point,
but no periods of significant strengthening are expected during the
next 5 days. The official intensity forecast remains near the IVCN
and HCCA intensity consensus aids.

The tropical storm continues to move westward, near 12 kt. This
should generally continue for the next couple of days until Philippe
approaches the aforementioned trough. At that point, as long as the
tropical storm has strengthened slightly as expected, it should
begin to turn northwestward, and then northward, influenced by the
deeper-layer steering flow imparted by the trough. The official
track forecast has been shifted slightly northeastward and slower
compared to the previous one, and is close to the latest HCCA
forecast.


FORECAST POSITIONS AND MAX WINDS

INIT  23/2100Z 15.6N  39.7W   35 KT  40 MPH
 12H  24/0600Z 15.7N  41.6W   40 KT  45 MPH
 24H  24/1800Z 15.9N  43.8W   40 KT  45 MPH
 36H  25/0600Z 16.3N  46.0W   40 KT  45 MPH
 48H  25/1800Z 16.7N  48.3W   45 KT  50 MPH
 60H  26/0600Z 17.2N  50.0W   45 KT  50 MPH
 72H  26/1800Z 18.0N  51.4W   50 KT  60 MPH
 96H  27/1800Z 21.0N  53.5W   55 KT  65 MPH
120H  28/1800Z 24.0N  54.0W   60 KT  70 MPH

$$
Forecaster D. Zelinsky
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