[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT43 KNHC 292045
TCDAT3

Hurricane Franklin Discussion Number  37
NWS National Hurricane Center Miami FL       AL082023
500 PM AST Tue Aug 29 2023

Franklin has completed an eyewall replacement cycle this afternoon.
This was confirmed by an AMSR microwave pass at 1748Z, showing that
the outer eyewall has now become the dominant feature and the inner
eyewall has completely collapsed. In the last few hours, infrared
imagery has depicted cold cloud tops in the deep convection within
the new eyewall. The subjective and objective satellite estimates
have decreased slightly throughout the day, but still remain around
a T5.5 from TAFB and CIMSS ADT. Given these satellite estimates and
the structure depicted from microwave imagery, the initial intensity
for this advisory will remain 110 kt.

Franklin is moving northeastward at around 10 kt. This northeastward
motion is expected to continue for the next few days with an
increase in forward speed as Franklin 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 with both along- and cross-track differences beyond
48 h. The NHC track is near the previous advisory and lies in the
middle of the guidance envelope, close to the consensus aids. 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.

Franklin could fluctuate in intensity now that it has completed the
eyewall replacement cycle. But, it should gradually weaken in the
near term, as it begins to move northward over cooler waters, with
some increase in northwesterly wind shear. Vertical wind shear is
forecast to increase further in about 36 h, with further weakening
anticipated. The guidance this cycle has come into better agreement
with the timing of extratropical transition in about 72 h, and this
is now reflected in the latest NHC forecast.


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  29/2100Z 31.4N  69.9W  110 KT 125 MPH
 12H  30/0600Z 32.7N  68.7W  105 KT 120 MPH
 24H  30/1800Z 34.3N  66.5W  100 KT 115 MPH
 36H  31/0600Z 35.4N  63.5W   95 KT 110 MPH
 48H  31/1800Z 36.6N  59.8W   85 KT 100 MPH
 60H  01/0600Z 37.9N  55.2W   75 KT  85 MPH
 72H  01/1800Z 40.6N  50.2W   70 KT  80 MPH...POST-TROP/EXTRATROP
 96H  02/1800Z 46.0N  40.2W   65 KT  75 MPH...POST-TROP/EXTRATROP
120H  03/1800Z...DISSIPATED

$$
Forecaster Kelly/Reinhart
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