Tropical Storm Leslie Discussion Number  10
NWS National Hurricane Center Miami FL       AL132024
500 PM AST Fri Oct 04 2024

The convective structure of Leslie has become better organized this 
afternoon with a more symmetrical convective shield. There have not 
been any helpful microwave or scatterometer passes the last several 
hours to help evaluate the structure further. The latest subjective 
Dvorak satellite intensity estimates were T/3.5 and T/4.0, from TAFB 
and SAB respectively. Using a blend of these estimates, the initial 
intensity is set to 60 kt for this advisory.

Leslie is moving slowly west-northwestward at 290/6 kt, and this 
motion is expected to continue as the storm rounds the subtropical 
ridge anchored over the east Atlantic. Leslie should continue 
west-northwestward then turn more northwestward by the end of the 
weekend with a slight increase in forward speed through the end of 
the forecast period. The track guidance is fairly well clustered and 
the NHC track lies near the consensus aids.

The intensity forecast has become a little more uncertain with 
varying model solutions the last few model cycles, especially with 
the peak intensity and potential weakening towards the middle to end 
of the period. Northeasterly shear from Kirk has started to weaken 
over the system this afternoon, and that has likely aided the 
improved convective pattern. Leslie will be within a favorable 
atmospheric and oceanic environment for steady strengthening over 
the next 2 days or so. Beyond that time models begin to plateau the 
strengthening or start a weakening trend, as Leslie encounters some 
westerly shear and a drier air mass.  There is a notable difference 
between the GFS and ECMWF in how hostile the environment will be by 
five days, with the ECMWF showing more shear, a much drier air 
mass, and a much weaker Leslie.  One other issue is that the 
forecast track is expected to take Leslie over the cold wake left 
behind from Hurricane Kirk. Given the lowering intensity guidance 
and varying model solutions, the NHC intensity forecast has been 
adjusted downward, but still lies at the higher end of the guidance 
envelope. Additional adjustments to the intensity forecast may be 
needed on later advisories.


FORECAST POSITIONS AND MAX WINDS

INIT  04/2100Z 10.3N  33.6W   60 KT  70 MPH
12H  05/0600Z 10.7N  34.6W   70 KT  80 MPH
24H  05/1800Z 11.2N  35.9W   75 KT  85 MPH
36H  06/0600Z 12.2N  37.1W   80 KT  90 MPH
48H  06/1800Z 13.5N  38.3W   80 KT  90 MPH
60H  07/0600Z 14.9N  39.8W   80 KT  90 MPH
72H  07/1800Z 16.3N  41.6W   75 KT  85 MPH
96H  08/1800Z 19.0N  45.0W   75 KT  85 MPH
120H  09/1800Z 21.5N  48.2W   70 KT  80 MPH

$$
Forecaster Kelly