Official Discussion issued by the National Hurricane Center

Franklin (AL082023) DATA RELEASED: 8/28/2023 3:00:00 AM UTC

Copy of official data

Hurricane Franklin Discussion Number  30
NWS National Hurricane Center Miami FL       AL082023
1100 PM EDT Sun Aug 27 2023

Franklin is becoming better organized tonight. A ragged eye has 
emerged in conventional satellite imagery during the past few hours, 
and the Air Force Hurricane Hunters reported a closed eyewall during 
recent passes through the center. Aircraft data indicated the 
minimum pressure has continued to fall, with a 00 UTC dropsonde 
reporting a pressure of 964 mb. Since the plane departed, the 
satellite structure of Franklin has markedly improved, with very 
cold cloud tops wrapping around the eastern portion of the 
circulation. The initial intensity of 90 kt is supported by recent 
objective estimates from UW-CIMSS and a T5.0 subjective Dvorak 
classification from TAFB at 00 UTC.

Recent satellite images suggest the hurricane is finally turning 
more northward as expected, and the initial motion is 
north-northwestward (330/7 kt). A gradual turn to the north and 
north-northeast is forecast during the next couple of days as 
Franklin moves around the western periphery of a high pressure 
ridge. The track guidance is in good agreement on this portion of 
the forecast, and only minor westward adjustments were made 
following the latest HCCA and TVCA aids. Thereafter, track 
uncertainty increases regarding Franklin's interaction with a 
deep-layer trough moving off the U.S. east coast by midweek. The GFS 
and ECMWF lie on opposite sides of the guidance envelope, with an 
850 n-mi spread at 96 h. Given the greater than normal uncertainty, 
the NHC track forecast remains close to the multi-model consensus 
aids at days 3-5, showing a gradually faster east-northeastward to 
northeastward motion during this period.

Based on recent satellite trends, it appears that the shear has 
weakened and the inner core of Franklin has become more solidified. 
Thus, the hurricane could be primed to strengthen in the near term 
within a low shear environment over very warm SSTs. The NHC forecast 
brings Franklin to major hurricane intensity in 12 h with more 
strengthening thereafter, in best agreement with some of the 
regional hurricane models and slightly above the HCCA/IVCN aids. As 
the hurricane recurves, increased deep-layer shear and cooler waters 
should induce some weakening, although the wind field will expand 
while the hurricane moves further into the mid-latitudes. This 
forecast shows Franklin becoming extratropical at day 5, although 
the timing could be refined based on future track forecasts.  

Although the core of Franklin is forecast to pass west and north of 
Bermuda during the next few days, its expanding wind field will 
likely require a tropical storm watch for the island on Monday.


INIT  28/0300Z 26.4N  70.5W   90 KT 105 MPH
12H  28/1200Z 27.3N  71.0W  100 KT 115 MPH
24H  29/0000Z 28.9N  71.2W  110 KT 125 MPH
36H  29/1200Z 30.4N  70.7W  115 KT 130 MPH
48H  30/0000Z 32.2N  69.5W  110 KT 125 MPH
60H  30/1200Z 33.8N  67.3W  100 KT 115 MPH
72H  31/0000Z 35.2N  64.2W   95 KT 110 MPH
96H  01/0000Z 37.5N  57.0W   80 KT  90 MPH
120H  02/0000Z 42.0N  49.5W   65 KT  75 MPH...POST-TROP/EXTRATROP

Forecaster Reinhart