[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT42 KNHC 010851
TCDAT2

Tropical Storm Philippe Discussion Number  32
NWS National Hurricane Center Miami FL       AL172023
500 AM AST Sun Oct 01 2023

The center of Philippe has become exposed to the northwest of the
large convective mass seen infrared satellite imagery.  A very
timely AMSR2 microwave overpass helped to pinpoint the center
location around 0600 UTC, and since that time the center has become
more apparent in the geostationary satellite imagery.  Philippe is
still producing a large area of convection with clouds tops colder
than -80 deg C to the southeast of its center.  The latest Dvorak
satellite estimates range from 45 kt from SAB to 55 kt from TAFB.
The initial intensity is held at 45 kt in agreement with the
earlier scatterometer data.  An Air Force Reserve Hurricane Hunter
aircraft is scheduled to investigate Philippe again this morning.

Philippe is moving a little faster toward the west overnight.  A
weak mid-level ridge to the northeast of the cyclone should begin
to steer Philippe west-northwestward to northwestward by later
today, and that motion is expected to continue into Monday.  The
track guidance has once more shifted westward during the first
couple of days, which has again necessitated a westward shift in
the NHC track forecast during that time.  The new track forecast is
a little closer to the northern Leeward Islands.  It should be
noted that the model guidance continues to show very little outward
extent of tropical-storm-force winds over the western semicircle of
Philippe through 48 hours, however given the typical track forecast
uncertainty tropical storm watches or warnings could be required
for a portion of the northern Leeward Islands later today.  After
48 hours, Philippe is expected to turn northward as it moves around
the western side of the ridge.  Later in the forecast  period, a
mid-tropospheric trough over the western Atlantic should cause
Philippe to turn north-northeastward.

The global models and the SHIPS intensity guidance indicate that
the west-northwesterly vertical shear over Philippe will remain
strong during the next couple of days.  Therefore, little change in
strength is expected during that time.  Later in the forecast
period, the vertical shear could lessen somewhat allowing Philippe
to strengthen.  The intensity models are generally lower this
cycle, and the NHC forecast has been adjusted downward but it
remains at the upper end of guidance.

KEY MESSAGES:

1. Philippe is forecast to pass near or just northeast of the
northern Leeward Islands Monday and Monday night.  Interests
there should continue to monitor the progress of this system as
tropical storm watches or warnings could be required for a portion
of that area later today.


FORECAST POSITIONS AND MAX WINDS

INIT  01/0900Z 16.4N  58.2W   45 KT  50 MPH
 12H  01/1800Z 16.9N  58.9W   45 KT  50 MPH
 24H  02/0600Z 17.6N  59.8W   45 KT  50 MPH
 36H  02/1800Z 18.4N  60.8W   45 KT  50 MPH
 48H  03/0600Z 19.2N  61.3W   50 KT  60 MPH
 60H  03/1800Z 20.4N  61.8W   50 KT  60 MPH
 72H  04/0600Z 21.9N  62.0W   55 KT  65 MPH
 96H  05/0600Z 25.5N  61.6W   65 KT  75 MPH
120H  06/0600Z 28.9N  59.8W   70 KT  80 MPH

$$
Forecaster Brown
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