NHC125 WTNT43 KNHC 080240 TCDAT3 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
Originally Posted at:
NATIONAL HURRICANE CENTER and CENTRAL PACIFIC HURRICANE CENTER
At The NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
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