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Tropical Storm Franklin Forecast Discussion

WTNT43 KNHC 252037

Tropical Storm Franklin Discussion Number  21
NWS National Hurricane Center Miami FL       AL082023
500 PM AST Fri Aug 25 2023

Franklin's low-level center remains exposed this afternoon on 
visible satellite imagery. Strong vertical wind shear continues to 
affect the asymmetric system, with the deep convection displaced on 
the eastern side of the storm. The Air Force and NOAA Hurricane 
Hunters have been in the system much of the day and show that the 
flight-level winds and pressure have remained steady. Subjective 
Dvorak estimates from TAFB and SAB also remain unchanged from the 
previous advisory. Given the data from the Hurricane Hunters and 
these satellite estimates, the initial intensity for this advisory 
remains at 45 kt.

The storm is moving slowly to the east-northeast at about 5 kt, 
around the base of a broad mid- to upper-level trough. This 
east-northeast to northeast motion is expected to continue through 
tonight as ridging builds to the east of Franklin over the central 
Atlantic and the trough drops southwestward.   Franklin will then 
turn more northward late this weekend into early next week, with the 
core of the system probably moving to the west of Bermuda on Monday 
and Tuesday.  By the middle of next week, Franklin is forecast to 
turn to the northeast and accelerate between the ridge and a 
mid-latitude trough over eastern Canada and the northeast U.S.  The 
NHC track forecast has shifted slightly eastward in the short term 
given the recent motion. At long range, the guidance envelope and 
consensus aids this cycle were to the right of the previous forecast 
track. The official NHC forecast was adjusted slightly to the east, 
but lies west of the consensus aids for this cycle.

Strong westerly vertical wind shear should remain over Franklin for 
the next 24 hours or so, which will probably limit much 
strengthening.  In a day or two, strengthening is forecast as the 
wind shear decreases and Franklin remains over very warm sea surface 
temperatures.  Franklin is expected to become a hurricane early next 
week and should reach a peak intensity near major hurricane strength 
by day 4. By the end of the forecast period, a gradual weakening 
trend is forecast as Franklin moves over cooler waters and into a 
stronger vertical wind shear environment. The intensity guidance was 
slightly weaker in the short term, and the official intensity 
forecast followed these trends. In the long term, the peak intensity 
forecast remains unchanged and near the consensus aids.


INIT  25/2100Z 21.9N  67.2W   45 KT  50 MPH
 12H  26/0600Z 22.0N  66.5W   45 KT  50 MPH
 24H  26/1800Z 22.8N  66.6W   50 KT  60 MPH
 36H  27/0600Z 23.8N  66.9W   55 KT  65 MPH
 48H  27/1800Z 25.4N  67.7W   60 KT  70 MPH
 60H  28/0600Z 27.3N  68.5W   70 KT  80 MPH
 72H  28/1800Z 29.2N  68.9W   85 KT 100 MPH
 96H  29/1800Z 33.0N  67.7W   95 KT 110 MPH
120H  30/1800Z 37.8N  62.7W   80 KT  90 MPH

Forecaster Kelly/Blake

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