####018003198####
WTNT42 KNHC 290838

TCDAT2

 

Tropical Storm Philippe Discussion Number  24

NWS National Hurricane Center Miami FL       AL172023

500 AM AST Fri Sep 29 2023

 

A 0546 UTC GMI microwave pass showed that Philippe continues to 

have a broad circulation, with the low-level center located 

somewhere near the northwestern edge of a large area of deep 

convection.  There is a large range in the subjective Dvorak 

estimates (30-55 kt), but the various objective numbers from 

UW-CIMSS are in closer agreement (35-45 kt).  Using a blend of 

these values, as well as ASCAT data from last evening, Philippe's 

intensity is held at 40 kt.



While there is a bit of uncertainty in the exact location of the 

center, the storm does appear to be drifting toward the southwest 

(235 degrees) at about 2 kt.  Philippe's movement during the next 

3-4 days is likely to be dictated by binary interaction with 

Tropical Storm Rina to the east.  The bulk of the track guidance 

indicates that Philippe will dip farther toward the southwest during 

the next 48 hours due to Rina's influence, but then turn toward the 

northwest and north on days 3 through 5 as a mid-tropospheric high 

builds over the central Atlantic.  The new NHC track forecast is 

not much different from the previous prediction and is close to the 

TVCA and HCCA consensus aids.  The HAFS regional hurricane models 

show little to no interaction between Philippe and Rina during the 

next few days.  However, with the two storms located only 500 n mi 

apart from each other, some degree of interaction is likely, and 

therefore the western solutions shown by those models (near or over 

the northern Leeward Islands) appear to be outliers at this time.  

That said, there continues to be larger-than-normal uncertainty in 

Philippe's future track.



A combination of shear, dry air, and Philippe's proximity to Rina 

are likely to cause little change in intensity for the next day or 

so.  However, the global models have trended toward Philippe not 

only surviving the next few days, but also deepening in an 

environment of increasing upper-level divergence (and still over 

very warm waters of 29-30 degrees Celsius).  The NHC intensity 

forecast has been nudged upward from 36 hours onward, although it 

still sits well below most of the intensity models, including the 

consensus aids, during the latter part of the forecast period.  

Until it becomes more clear how Philippe will evolve over the next 

couple of days, the official intensity forecast will remain on the 

conservative side, but future adjustments to the forecast are 

becoming more likely.

 

 

FORECAST POSITIONS AND MAX WINDS

 

INIT  29/0900Z 18.5N  55.2W   40 KT  45 MPH

 12H  29/1800Z 18.3N  55.4W   40 KT  45 MPH

 24H  30/0600Z 17.9N  55.7W   40 KT  45 MPH

 36H  30/1800Z 17.4N  56.0W   45 KT  50 MPH

 48H  01/0600Z 17.1N  56.4W   50 KT  60 MPH

 60H  01/1800Z 17.1N  56.8W   50 KT  60 MPH

 72H  02/0600Z 17.6N  57.2W   55 KT  65 MPH

 96H  03/0600Z 20.0N  57.9W   55 KT  65 MPH

120H  04/0600Z 23.1N  58.1W   55 KT  65 MPH

 

$$

Forecaster Berg