Official Discussion issued by the National Hurricane Center

Leslie (AL132024) DATA RELEASED: 10/8/2024 3:00:00 AM UTC

Copy of official data

Hurricane Leslie Discussion Number  23
NWS National Hurricane Center Miami FL       AL132024
1100 PM AST Mon Oct 07 2024

Deep convection has continued to pulse this evening in Leslie, 
with the larger cirrus shield taking on an amorphous shape. Under 
the cirrus canopy, the last few SSMIS microwave passes suggest that 
the hurricane's structure continues to degrade, with the tighter 
inner-core seen yesterday at this time no longer observed. The 
subjective Dvorak estimates this evening were T4.0/65 kt from SAB 
and T4.5 from TAFB. However, the objective intensity estimates have 
decreased further, with the most recent DMINT down to 61 kt. Thus, 
the initial intensity was lowered slightly to 65 kt this advisory. 
The wind radii were adjusted a bit outward thanks to a helpful 
ASCAT-B pass earlier this evening. 

Leslie has maintained its northwestward motion, currently estimated 
at 310/12 kt. There is not a lot of new information to provide for 
the track reasoning this cycle, with Leslie rounding the western 
side of a subtropical ridge to its northeast. The hurricane should 
maintain its northwestward motion over the next day or two, followed 
by a turn northward towards the end of this week once it reaches the 
western edge of this synoptic steering feature. The track guidance 
this cycle is just a notch left of the prior forecast, and the NHC 
track has been nudged in that direction, but is still quite close to 
the prior track forecast.

Leslie is currently battling a fairly marginal environment with 
mid-level southerly shear of 20-25 kt continuing to undercut the 
seemingly more favorable 200 mb upper-level flow. A ribbon of very 
dry environmental air that can be seen on GOES-16 water vapor 
imagery, which is likely being imported near Leslie's center, 
contributing to its degraded inner-core structure seen on microwave 
imagery. This shear is expected to persist, before quickly shifting 
out of the north and increasing above 40 kt after 48 h. Intensity 
guidance remains insistent that Leslie will weaken slowly at first, 
and then more dramatically after this shear increases. The GFS, 
ECMWF, and HAFS-A/B runs show Leslie quickly becoming devoid of 
convection after 72 h due to this shear, and the NHC forecast 
continues to show Leslie becoming a post-tropical cyclone in 96 h.


FORECAST POSITIONS AND MAX WINDS

INIT  08/0300Z 18.4N  43.5W   65 KT  75 MPH
12H  08/1200Z 19.6N  44.9W   60 KT  70 MPH
24H  09/0000Z 21.0N  46.5W   55 KT  65 MPH
36H  09/1200Z 22.2N  47.7W   55 KT  65 MPH
48H  10/0000Z 23.0N  48.6W   55 KT  65 MPH
60H  10/1200Z 23.8N  49.5W   50 KT  60 MPH
72H  11/0000Z 25.0N  50.0W   40 KT  45 MPH
96H  12/0000Z 28.0N  48.5W   35 KT  40 MPH...POST-TROPICAL
120H  13/0000Z 32.0N  43.0W   30 KT  35 MPH...POST-TROP/REMNT LOW

$$
Forecaster Papin