[Tropical] Tropical Cyclone Discussion

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WTNT42 KNHC 260844
TCDAT2

Tropical Storm Philippe Discussion Number  12
NWS National Hurricane Center Miami FL       AL172023
500 AM AST Tue Sep 26 2023

West-southwesterly vertical wind shear, associated with an
upper-level low near 26N 50W, continues to affect Philippe.  The
low-level center of the tropical cyclone is located near the
western edge of an area of rather disorganized deep convection.
Some sporadic convection has been redeveloping nearer to the center
of the system, but overall Philippe's cloud pattern remains
disheveled in appearance and lacks banding features.  The current
intensity estimate is kept at 45 kt in deference to the earlier
scatterometer data.  However, subjective and objective Dvorak
intensity estimates are somewhat lower.

The global models indicate that the vertical shear over Philippe
is not likely to abate significantly during the forecast period,
with upper-tropospheric westerlies dominating the flow to the north
and northeast of the Greater Antilles through 120 hours.  Also, the
model guidance indicates that Philippe will be encountering a
somewhat drier low- to mid-level air mass during the next several
days.  These environmental factors should lead to gradual weakening,
and thus Philippe is forecast to become a depression and then a
remnant low in 3 and 5 days, respectively.  This is in good
agreement with the corrected consensus intensity model, HCCA,
guidance.

Over the past day or so, the storm has been moving westward to
west-northwestward and the current motion estimate is 285/11 kt.  A
weak mid-level ridge is expected to be maintained to the north
of Philippe for the next few days, which is likely to keep steering
the cyclone on a generally west-northwestward track.  Later in the
forecast period, Philippe should be a weaker, shallower system and
move on a mainly westward heading, following the low-level easterly
flow.  The official track forecast is similar to the previous NHC
track, only a little to the left and slightly faster in 3-5 days.
This lies between the model consensus and the latest ECMWF
prediction, which is even faster and a little farther south.


FORECAST POSITIONS AND MAX WINDS

INIT  26/0900Z 17.7N  49.0W   45 KT  50 MPH
 12H  26/1800Z 18.2N  50.4W   45 KT  50 MPH
 24H  27/0600Z 19.1N  52.1W   45 KT  50 MPH
 36H  27/1800Z 20.1N  53.9W   45 KT  50 MPH
 48H  28/0600Z 21.0N  55.4W   40 KT  45 MPH
 60H  28/1800Z 21.6N  56.9W   40 KT  45 MPH
 72H  29/0600Z 21.9N  58.2W   35 KT  40 MPH
 96H  30/0600Z 21.8N  60.9W   30 KT  35 MPH
120H  01/0600Z 21.8N  63.6W   25 KT  30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Pasch
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