ZCZC MIATCDAT3 ALL
TTAA00 KNHC DDHHMM
 
Tropical Storm Franklin Discussion Number  22
NWS National Hurricane Center Miami FL       AL082023
1100 PM AST Fri Aug 25 2023
 
Westerly shear continues to affect Franklin tonight, as evidenced by 
the sharp edge to its cold cloud tops on infrared satellite images. 
However, the low-level center that was exposed earlier today appears 
to have moved under the western edge of the convective canopy. An 
Air Force Reserve Hurricane Hunter aircraft flew the storm at 700 mb 
this evening and reported peak flight-level winds of 56 kt, with 
believable SFMR winds in the 45-55 kt range. These data warrant a 
slight increase to the initial intensity (50 kt), especially given a 
recent dropsonde that suggests the surface pressure has fallen to 
996 mb tonight. A recent ASCAT-B pass over Franklin further supports 
this, with peak wind vectors slightly above 45 kt. Note that the 
initial intensity of Franklin is more uncertain than normal, with 
there being a large spread between some of the aircraft data and the 
various objective and subjective satellite estimates.
 
The intense convection closer to the center of Franklin appears to 
have drawn the surface center more northeastward, and the initial 
motion is an uncertain 60/7 kt. A high pressure ridge building to 
the east of Franklin is expected to steer the cyclone more northward 
and north-northwestward this weekend and into early next week. Then, 
a deep-layer trough is forecast to move across the northeastern U.S. 
and eastern Canada by midweek. This should cause Franklin to 
accelerate northeastward deeper into the mid latitudes through the 
end of the forecast period. The updated NHC track forecast lies to 
the east of the previous one during the first 60-72 h of the period, 
mainly a result of the eastward adjustment to the initial position 
of Franklin. There are some notable forward speed differences beyond 
72 h, with the GFS significantly faster than the rest of the global 
and regional models. With the NHC forecast remaining near the 
multi-model consensus aids, no notable changes were made to this 
portion of the track forecast.
 
The westerly shear that has plagued Franklin for the past couple of
days is expected to decrease during the next 24-36 h. So while only
modest strengthening is forecast in the near term, more significant
strengthening seems likely thereafter as the cyclone moves over
very warm SSTs (29-30 deg C) and within a more favorable dynamic
environment. The updated forecast shows Franklin becoming a
hurricane by 48 h and peaking near major hurricane intensity in
72-96 h, in good agreement with the latest HCCA and IVCN aids. As
Franklin accelerates to higher latitudes, cooler waters and
increased deep-layer shear will induce weakening and eventually
extratropical transition beyond the end of the forecast period.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  26/0300Z 22.4N  66.2W   50 KT  60 MPH
 12H  26/1200Z 23.0N  66.0W   55 KT  65 MPH
 24H  27/0000Z 23.9N  66.3W   55 KT  65 MPH
 36H  27/1200Z 25.3N  67.0W   60 KT  70 MPH
 48H  28/0000Z 27.0N  67.9W   70 KT  80 MPH
 60H  28/1200Z 28.8N  68.4W   80 KT  90 MPH
 72H  29/0000Z 30.5N  68.4W   95 KT 110 MPH
 96H  30/0000Z 34.7N  66.5W   95 KT 110 MPH
120H  31/0000Z 40.0N  60.0W   75 KT  85 MPH
 
$$
Forecaster Reinhart
 
NNNN