[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT43 KNHC 282035
TCDAT3

Hurricane Franklin Discussion Number  33
NWS National Hurricane Center Miami FL       AL082023
500 PM EDT Mon Aug 28 2023

Visible and infrared satellite imagery depicts Franklin remains a
powerful major hurricane this afternoon. The eye has cleared out and
warmed, with a thick symmetric eyewall tightly wrapped around the
center. Subjective and objective satellite estimates have remained
fairly steady throughout the day, around T6.5. Given that the
satellite appearance remains similar to earlier today when we had
aircraft reconnaissance data, the intensity remains at 125 kt for
this advisory. Air Force Reserve Hurricane Hunters will be
investigating the system later this evening.

Franklin is moving northward at 350/8 kt. A northward then
northeastward motion is forecast during the next 48 hours as
Franklin rounds the western edge of the subtropical ridge. In a
couple of days, a deep trough is expected to move off the northeast
coast of the U.S. and eastern Canada, with Franklin becoming
captured in the southwesterly flow, causing an increase in forward
motion to the northeast. The model guidance for this cycle remained
in fairly good agreement except for the ECMWF, which shifted back to
the right. There is still a difference in the a long track guidance,
with the GFS being on the faster side of the model envelope. The NHC
track forecast is fairly similar to the previous, and lies near the
corrected consensus aids.

Some additional intensification is possible as Franklin remains
over warm sea-surface temperatures and low vertical wind shear. The
latest peak intensity is unchanged from the previous forecast,
bringing Franklin to a strong Category 4 hurricane. The short
term forecast is subject to fluctuations in inner core changes, or
eyewall replacement cycles, which could occur at any time, making
the peak intensity forecast a little more challenging. Some gradual
weakening is forecast in about 24 hours as models indicate a
increase in northwesterly shear. Toward the end of the forecast
period, further weakening is expected as Franklin encounters
increased vertical wind shear and moves over cooler SSTs. Models
are in fairly good agreement with the system becoming an
extratropical cyclone around 96 h, and the forecast now
explicitly shows this transition occuring in 96 h.

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  28/2100Z 28.5N  71.0W  125 KT 145 MPH
 12H  29/0600Z 29.7N  71.1W  135 KT 155 MPH
 24H  29/1800Z 31.3N  70.3W  130 KT 150 MPH
 36H  30/0600Z 33.0N  68.8W  120 KT 140 MPH
 48H  30/1800Z 34.9N  66.3W  110 KT 125 MPH
 60H  31/0600Z 37.2N  62.0W  100 KT 115 MPH
 72H  31/1800Z 39.6N  57.3W   90 KT 105 MPH
 96H  01/1800Z 45.6N  48.3W   75 KT  85 MPH...POST-TROP/EXTRATROP
120H  02/1800Z 50.4N  37.6W   60 KT  70 MPH...POST-TROP/EXTRATROP

$$
Forecaster Kelly/Brown
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