####018003393####
WTNT42 KNHC 010245

TCDAT2

 

Tropical Storm Philippe Discussion Number  31

NWS National Hurricane Center Miami FL       AL172023

1100 PM AST Sat Sep 30 2023

 

Philippe's convective cloud pattern remains rather ragged-looking,

but there are very cold cloud tops of -80 deg C or colder over the

southeastern part of the circulation.  The center of circulation is

estimated to be near the northwestern edge of the main area of deep

convection.  There is little evidence of banding features at this

time.  The current intensity estimate is kept at 45 kt in agreement 

with the latest Dvorak classification from TAFB although objective 

satellite estimates are somewhat lower.  A recent scatterometer 

pass showed slightly higher winds over the southeastern quadrant 

but these are believed to be rain-inflated.  Another Hurricane 

Hunter aircraft is scheduled to investigate Philippe tomorrow 

morning to check on the intensity of the storm.

 

The motion is somewhat uncertain since the center is not easy to

locate in nighttime satellite imagery.  However it appears that

Philippe is moving more to the right and the initial motion

estimate is now 230/4 kt.  Steering currents are expected to remain 

ill-defined for the next day or two, but a weak mid-level high to 

the northeast of the system should cause Philippe to turn 

northwestward on Sunday.  In about 3 days, a turn to the north is 

expected as the cyclone moves along the western side of the high.  

Late in the forecast period, the system should turn toward the 

north-northeast on the southeast side of a mid-tropospheric trough 

over the western Atlantic.  The latest track guidance for the next 

48 hours or so, in particular the new GFS, has shifted westward 

from the previous cycle.  This has resulted in a westward shift of 

the model consensus and necessitated a westward shift in the NHC 

track as well, which is now 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, and this forecast 

still does not necessitate the issuance of tropical storm watches 

for those islands.  However, interests there should continue to 

monitor the progress of Philippe.

 

Based on the global model forecasts, the system is likely to

continue experiencing significant vertical wind shear for the next

day or two.  Therefore only a slow increase in intensity is

forecast during the next couple of days.  Later in the forecast 

period, vertical shear is expected to lessen somewhat which should 

allow the system to strengthen into a hurricane, as suggested by 

the regional hurricane model, HAFS-A.  However, the official 

intensity forecast is now above most of the model guidance.

 

 

FORECAST POSITIONS AND MAX WINDS

 

INIT  01/0300Z 16.1N  57.0W   45 KT  50 MPH

 12H  01/1200Z 16.5N  57.7W   45 KT  50 MPH

 24H  02/0000Z 17.1N  58.6W   50 KT  60 MPH

 36H  02/1200Z 17.8N  59.4W   55 KT  65 MPH

 48H  03/0000Z 18.6N  60.3W   60 KT  70 MPH

 60H  03/1200Z 19.6N  61.0W   60 KT  70 MPH

 72H  04/0000Z 21.1N  61.2W   65 KT  75 MPH

 96H  05/0000Z 24.8N  61.1W   75 KT  85 MPH

120H  06/0000Z 28.5N  59.2W   80 KT  90 MPH

 

$$

Forecaster Pasch