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Hurricane Franklin Discussion Number  47
NWS National Hurricane Center Miami FL       AL082023
500 AM AST Fri Sep 01 2023
 
Franklin has a much more asymmetric appearance this morning,
indicative of the increasingly disruptive upper-wind pattern
associated with an approaching mid-latitude baroclinic zone.  In 
fact, the remaining deep convective mass is about 100 mi southeast 
of the surface center.  The initial intensity is lowered to 70 kt 
and is based on a compromise of the available subjective and 
objective intensity estimate techniques. 
 
Franklin is showing signs of losing its tropical characteristics
while drier, more stable mid-level air and increasing northwesterly
shear impedes over the northwest portion of the cyclone. 
Consequently, the completion of an extratropical transition is
expected later tonight or early Saturday.  However, little change in
strength is forecast, and Franklin should maintain its 
hurricane-force sustained winds through the weekend.  By early next 
week, gradual weakening is expected, which agrees with a blend of
the intensity consensus guidance and the statistical-dynamic SHIPS
models.
 
Franklin's initial motion is estimated to be east-northeastward or 
060/16 kt.  An increase in forward speed toward the northeast is 
forecast.  At the same time, Franklin moves within the mid-latitude 
steering flow between high pressure to the east, over the central 
Atlantic, and an extensive baroclinic system moving out of the 
Canadian Maritimes.  Global model spread continues to increase 
beyond day 3.  Two scenarios are possible.  The European models 
take a southeastward track while interacting with a larger 
cut-off low meandering west of the Iberian peninsula.  The other 
solution involves the GFS and the regional guidance which gradually 
turns the cyclone northeastward to northward over the northeast 
Atlantic. The official forecast track indicates a blend of the two 
model clusters, lying between both, and is close to the multi-model 
consensus aid. 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  01/0900Z 37.8N  57.0W   70 KT  80 MPH
 12H  01/1800Z 39.1N  54.3W   70 KT  80 MPH
 24H  02/0600Z 41.2N  49.8W   70 KT  80 MPH...POST-TROP/EXTRATROP
 36H  02/1800Z 43.5N  45.5W   65 KT  75 MPH...POST-TROP/EXTRATROP
 48H  03/0600Z 45.7N  41.1W   60 KT  70 MPH...POST-TROP/EXTRATROP
 60H  03/1800Z 47.2N  36.6W   50 KT  60 MPH...POST-TROP/EXTRATROP
 72H  04/0600Z 48.4N  32.8W   40 KT  45 MPH...POST-TROP/EXTRATROP
 96H  05/0600Z 50.3N  27.9W   35 KT  40 MPH...POST-TROP/EXTRATROP
120H  06/0600Z 51.6N  25.0W   30 KT  35 MPH...POST-TROP/EXTRATROP
 
$$
Forecaster Roberts
 
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