Official Discussion issued by the National Hurricane Center

Franklin (AL082023) DATA RELEASED: 8/24/2023 3:00:00 PM UTC

Copy of official data

Tropical Storm Franklin Discussion Number  16
NWS National Hurricane Center Miami FL       AL082023
1100 AM AST Thu Aug 24 2023

Franklin appears a little better organized this morning, with a 
recent convective burst near the center with cloud tops as cold as 
-80C. The morning Air Force Reserve Reconnaissance mission into 
Franklin indicates the storm has intensified a bit, with peak flight 
level winds of 62 kt at 850-mb, SFMR winds in the 50-55 kt range, 
and a recent dropsonde just to the northeast of the center reported 
a surface wind of 48 kt. The initial intensity based on this 
data is set at 50 kt for this advisory. 

Fixes from the aircraft indicate that Franklin has begun to move to 
the northeast, with the motion estimated at 040/6 kt. This motion, 
or even a bit more of a turn to the east-northeast, should continue 
in the short-term as a weakness persists to the north of Franklin 
and its motion is more driven by a weak mid-level ridge over the 
eastern Caribbean Sea. By 48 hours, however, the mid-level ridging 
is expected to become more pronounced east of the storm, leading to 
a sharp turn to the north. The biggest change in the guidance this 
cycle is a slower motion, especially in the first 48-60 hours. The 
latest NHC track forecast is also slower, but not quite as slow as 
the TVCN and HCCA consensus aids in this time period. Later on, the 
track guidance continues to exhibit a fair amount of across track 
spread in a west-to-east fashion. The ECMWF remains on the left side 
of this guidance envelope, while the hurricane-regional models and 
GFS remain on the right side. For now, the NHC track will favor the 
right side of the guidance envelope, which happens to be near the 
prior track forecast and HCCA consensus aid. On the forecast track, 
Franklin should be passing by several hundred miles west of Bermuda 
between days 4-5. 

Franklin is continuing to gradually intensify this morning based on 
the in-situ aircraft data. However, from the satellite structure, 
the storm remains quite asymmetric due to about 20 kt of westerly 
vertical wind shear. This shear is expected to persist for at least 
another 36 hours, and only slow intensification is forecast over 
this time span. After that, a much more favorable upper-level 
pattern takes shape as an upper-level low cuts off to the southwest 
of the tropical cyclone, and most of the guidance responds to this 
change by showing more significant intensification. The NHC 
intensity forecast follows this solution, bringing Franklin to near 
major hurricane intensity in 96h, which remains near the higher end 
of the intensity guidance this cycle.


INIT  24/1500Z 22.2N  69.9W   50 KT  60 MPH
12H  25/0000Z 22.6N  68.9W   55 KT  65 MPH
24H  25/1200Z 23.0N  67.7W   55 KT  65 MPH
36H  26/0000Z 23.4N  66.9W   60 KT  70 MPH
48H  26/1200Z 23.9N  66.4W   65 KT  75 MPH
60H  27/0000Z 25.0N  66.6W   70 KT  80 MPH
72H  27/1200Z 26.6N  67.3W   80 KT  90 MPH
96H  28/1200Z 30.0N  68.5W   95 KT 110 MPH
120H  29/1200Z 34.5N  67.5W   90 KT 105 MPH

Forecaster Papin