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Hurricane Franklin Discussion Number  34
NWS National Hurricane Center Miami FL       AL082023
1100 PM EDT Mon Aug 28 2023
 
Franklin remains a powerful category 4 hurricane.  Satellite images 
show a clear and circular eye with a solid and symmetric ring of 
deep convection surrounding that feature.  The Air Force Hurricane 
Hunters have investigated Franklin during the past few hours and 
found 700-mb flight-level winds as high as 140 kt and maximum 
surface SFMR winds of 128 kt.  In addition, the minimum pressure 
based on dropsonde data is estimated to be 926 mb.  Based on these 
data, the initial intensity is set at 130 kt, which is close to the 
upper bound of category 4 status.
 
The major hurricane is now moving due northward at 9 kt.  A turn to 
the northeast is expected on Tuesday, with a steady increase in 
forward speed forecast during the next few days as the hurricane 
moves in progressively faster flow between a mid-level ridge 
over the central Atlantic and a mid- to upper-level trough over the 
northeastern U.S. and eastern Canada.  The models are in relatively 
good agreement during the next 72 hours, however, they diverge 
significantly after that.  The GFS shows a continued acceleration 
to the northeast with the trough eventually capturing Franklin. 
Conversely, the ECMWF shows the trough pulling away, leaving 
Franklin behind in weaker steering currents.  The NHC track forecast 
is roughly between those very different solutions, sticking close 
to the various consensus aids.

Franklin should maintain its strength overnight, but a steady 
weakening trend should begin on Tuesday as the hurricane moves over 
progressively cooler waters and into an environment of higher shear. 
Regardless, Franklin is expected to be a significant hurricane 
during the next few days.  Franklin should complete extratropical 
transition in 3 to 4 days when it crosses the northern wall of the 
Gulf Stream Current and moves into an environment of very strong 
shear.  The NHC intensity forecast is a little lower than the 
previous one and close to the HCCA and IVCN models.
 
 
KEY MESSAGES:
 
1. Tropical storm conditions are possible on Bermuda beginning
Wednesday morning, when Franklin is forecast to make its closest
approach to the island.
 
2. Life-threatening surf and rip currents are occurring along the
coast of the southeast United States. These conditions are
expected to spread northward along the remainder of the U.S.
east coast, Atlantic Canada, and Bermuda during the next couple of
days.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  29/0300Z 29.4N  71.0W  130 KT 150 MPH
 12H  29/1200Z 30.5N  70.8W  130 KT 150 MPH
 24H  30/0000Z 32.1N  69.7W  120 KT 140 MPH
 36H  30/1200Z 33.9N  67.7W  110 KT 125 MPH
 48H  31/0000Z 35.8N  64.5W  100 KT 115 MPH
 60H  31/1200Z 38.0N  60.3W   95 KT 110 MPH
 72H  01/0000Z 40.9N  55.3W   85 KT 100 MPH
 96H  02/0000Z 45.8N  45.9W   70 KT  80 MPH...POST-TROP/EXTRATROP
120H  03/0000Z 52.0N  38.5W   55 KT  65 MPH...POST-TROP/EXTRATROP
 
$$
Forecaster Cangialosi
 
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