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Hurricane Franklin Discussion Number  32
NWS National Hurricane Center Miami FL       AL082023
1100 AM EDT Mon Aug 28 2023
 
Visible, infrared and microwave imagery depict a strengthening major 
hurricane with a well-defined eye, a thick eyewall, and very cold 
cloud tops. This was further supported by data from the Air Force 
Reserve Hurricane Hunters, who have been investigating the storm 
this morning. Minimum pressure has decreased from the previous 
advisory based on a dropsonde measuring a pressure of 937 mb around 
12 UTC. Flight-level, SFMR winds and dropsondes in the eyewall 
indicate maximum sustained winds have increased to 125 kt. 
Subjective and object satellite estimates also have drastically 
increased with this advisory. Given these data, the initial 
intensity is raised to 125 kt for this advisory, and Franklin has 
rapidly intensified into a Category 4 major hurricane.
 
The hurricane continues to make a gradual turn northward, with the 
latest motion estimate 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. After 48 
hours, a deep trough is expected to move off the U.S. northeast 
coast and Canada, and has Franklin becoming captured in the 
southwesterly flow, with an increase in forward motion to the 
northeast. There is better agreement in cross-track guidance 
compared to the previous few advisories. However, there is still a 
slight difference in the along track guidance with the GFS being 
faster, and the ECMWF a little slower. The latest NHC track forecast 
is similar to the previous forecast, with only a minor nudge to the 
north.
 
Some additional intensification is possible today, as Franklin 
remains in a low shear environment and is over warm sea-surface 
temperatures. The latest intensity forecast peaks Franklin as a 
strong Category 4 major hurricane. However, inner core changes, such 
as eyewall replacement cycles, could occur at any time, making the 
peak intensity and short-term forecast a little more challenging. 
Some gradual weakening is forecast in about a day or so when models 
forecast a slight 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. 
The latest forecast shows the storm becoming a extratropical cyclone 
in 120 h, though this could occur sooner.
 
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  28/1500Z 27.8N  71.0W  125 KT 145 MPH
 12H  29/0000Z 29.0N  71.2W  135 KT 155 MPH
 24H  29/1200Z 30.7N  70.8W  130 KT 150 MPH
 36H  30/0000Z 32.5N  69.6W  120 KT 140 MPH
 48H  30/1200Z 34.5N  67.4W  110 KT 125 MPH
 60H  31/0000Z 36.3N  64.1W  100 KT 115 MPH
 72H  31/1200Z 38.7N  59.9W   90 KT 105 MPH
 96H  01/1200Z 44.5N  49.7W   75 KT  85 MPH
120H  02/1200Z 51.8N  39.8W   65 KT  75 MPH...POST-TROP/EXTRATROP
 
$$
Forecaster Kelly/Brown
 
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