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Hurricane Franklin Discussion Number  36
NWS National Hurricane Center Miami FL       AL082023
1100 AM EDT Tue Aug 29 2023

Visible, infrared, and microwave satellite imagery indicates that 
Franklin is undergoing an eyewall replacement cycle with an outer 
concentric band becoming more dominant. The inner eyewall has become 
a little more ragged, and has started to collapse on the northern 
side. A 1137z 91GHz/37GHz SSMIS microwave pass confirmed the outer 
eyewall is becoming more dominant as well. The subjective and 
objective Dvorak estimates were in fairly good agreement this cycle, 
with a data-T of 5.5 and Final-T of 6.0 from both TAFB and UW-CIMSS 
ADT. Given the ongoing inner structural changes and the slightly 
weaker appearance on satellite, the initial intensity for this 
advisory lowered to 115 kt for this advisory. 
 
Franklin is moving north-northeastward at around 10 kt. A more 
northeastward motion is expected later today as the hurricane rounds 
the edge of the subtropical ridge and gets caught in the 
southwesterly flow ahead of a mid-latitude trough moving off the 
northeast U.S. coast and Atlantic Canada. There still remains a good 
amount of spread in the track guidance envelope with the GFS faster 
and further north, and the ECMWF slower and further south. The NHC 
track lies in the middle of the guidance, near the consensus aids 
TVCA and HCCA. Even though the center of Franklin is forecast to 
pass to the northwest of Bermuda on Wednesday, tropical-storm-force 
winds associated with the hurricane are expected to extend well to 
the southeast of the center.
 
The intensity forecast remains similar to the previous forecast. 
Franklin is expected to continue weakening, as it begins to move 
northward over cooler waters. ECMWF and GFS SHIPS guidance also 
forecast the vertical wind shear to increase over the hurricane in 
about 36 h. The current NHC forecast has Franklin becoming 
extratropical in 4 days. There is some guidance, including the GFS, 
that have this transition occurring a little faster, while the 
ECMWF is a little slower with this transition.


KEY MESSAGES:
 
1. Tropical storm conditions are expected 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
east coast of the United States. These conditions are expected to 
continue during the next several days.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  29/1500Z 30.8N  70.4W  115 KT 130 MPH
 12H  30/0000Z 32.0N  69.6W  110 KT 125 MPH
 24H  30/1200Z 33.7N  67.7W  100 KT 115 MPH
 36H  31/0000Z 35.3N  64.8W   95 KT 110 MPH
 48H  31/1200Z 36.9N  60.8W   90 KT 105 MPH
 60H  01/0000Z 39.0N  55.7W   80 KT  90 MPH
 72H  01/1200Z 41.3N  50.6W   75 KT  85 MPH
 96H  02/1200Z 46.9N  42.9W   65 KT  75 MPH...POST-TROP/EXTRATROP
120H  03/1200Z 53.6N  34.4W   50 KT  60 MPH...POST-TROP/EXTRATROP
 
$$
Forecaster Kelly/Brown
 
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