Hurricane Leslie Forecast Discussion Number 31
Issued at 1100 PM AST Wed Oct 09 2024 000 WTNT43 KNHC 100244 TCDAT3 Hurricane Leslie Discussion Number 31 NWS National Hurricane Center Miami FL AL132024 1100 PM AST Wed Oct 09 2024 Since the previous advisory, a small eye feature has started appearing on geostationary infrared imagery with Leslie, surrounded by a ring of very cold (below -70 C) cloud top temperatures. This structure is also supported by an earlier SAR-RCM2 pass that showed a tight inner core with a radius of maximum wind that had contracted from yesterday. 00 UTC subjective Dvorak estimates from TAFB and SAB were T5.0/90-kt and T5.5/102-kt, respectively. Objective intensity estimates were somewhat lower, between 79-86 kt, and blending the data results in a 90 kt intensity this cycle. A Saildrone (SD-1036) appears to be near the path of Leslie, and is currently reporting sustained tropical-storm-force winds that are quickly increasing about 50 n mi northwest of the center. As noted previously, another saildrone (SD-1040) indicated that sea-surface temperatures near Leslie are warmer than expected, near 29 C. At the same time, the hurricane is in a very narrow region of low vertical wind shear that should persist for another 6-12 h. While the interpolated intensity guidance is a bit lower, the raw model output of all four of the hurricane-regional models (HAFS-A/B, HMON, HWRF) show Leslie briefly becoming a major hurricane in 12 h. Because the raw model output from these intensity aids has been outperforming the interpolated guidance over the past day, the NHC intensity forecast will now show a 100 kt peak tomorrow morning. However, this peak is likely to be short-lived, as strong upper-level northerly flow, via outflow from Milton and Invest 93L, will soon overtake the hurricane, likely leading to rapid weakening. Those same hurricane-regional models show Leslie weakening below hurricane intensity in 36 h, and that rapid weakening continues to be reflected in the latest intensity forecast. While sheared puffs of deep convection may continue for a subsequent day or two, eventually Leslie is likely to lose the necessary convective organization to be classified as a tropical cyclone. The NHC forecast continues to show Leslie becoming post-tropical by the end of the weekend, though this could occur sooner than forecast given the proximity of very dry environmental air and high shear affecting the system. Leslie continues to move northwestward, estimated at 315/7 kt this evening. The track forecast is more straightforward, with Leslie rounding the western edge of a subtropical ridge to its east, resulting in a gradual turn northward and then northeastward over the forecast period. With that said, there has been a notable westward and poleward shift in the guidance this cycle, and the NHC track forecast was moved in that direction, but not as far as the latest TVCN and HCCA consensus aids. FORECAST POSITIONS AND MAX WINDS INIT 10/0300Z 22.6N 49.3W 90 KT 105 MPH 12H 10/1200Z 23.3N 49.9W 100 KT 115 MPH 24H 11/0000Z 24.4N 50.4W 80 KT 90 MPH 36H 11/1200Z 26.0N 50.1W 55 KT 65 MPH 48H 12/0000Z 28.4N 48.4W 45 KT 50 MPH 60H 12/1200Z 30.7N 45.5W 45 KT 50 MPH 72H 13/0000Z 33.0N 41.6W 45 KT 50 MPH 96H 14/0000Z 36.0N 31.0W 40 KT 45 MPH...POST-TROPICAL 120H 15/0000Z 37.1N 21.9W 30 KT 35 MPH...POST-TROP/REMNT LOW $$ Forecaster Papin
Issued at 1100 PM AST Wed Oct 09 2024
000 WTNT43 KNHC 100244 TCDAT3 Hurricane Leslie Discussion Number 31 NWS National Hurricane Center Miami FL AL132024 1100 PM AST Wed Oct 09 2024 Since the previous advisory, a small eye feature has started appearing on geostationary infrared imagery with Leslie, surrounded by a ring of very cold (below -70 C) cloud top temperatures. This structure is also supported by an earlier SAR-RCM2 pass that showed a tight inner core with a radius of maximum wind that had contracted from yesterday. 00 UTC subjective Dvorak estimates from TAFB and SAB were T5.0/90-kt and T5.5/102-kt, respectively. Objective intensity estimates were somewhat lower, between 79-86 kt, and blending the data results in a 90 kt intensity this cycle. A Saildrone (SD-1036) appears to be near the path of Leslie, and is currently reporting sustained tropical-storm-force winds that are quickly increasing about 50 n mi northwest of the center. As noted previously, another saildrone (SD-1040) indicated that sea-surface temperatures near Leslie are warmer than expected, near 29 C. At the same time, the hurricane is in a very narrow region of low vertical wind shear that should persist for another 6-12 h. While the interpolated intensity guidance is a bit lower, the raw model output of all four of the hurricane-regional models (HAFS-A/B, HMON, HWRF) show Leslie briefly becoming a major hurricane in 12 h. Because the raw model output from these intensity aids has been outperforming the interpolated guidance over the past day, the NHC intensity forecast will now show a 100 kt peak tomorrow morning. However, this peak is likely to be short-lived, as strong upper-level northerly flow, via outflow from Milton and Invest 93L, will soon overtake the hurricane, likely leading to rapid weakening. Those same hurricane-regional models show Leslie weakening below hurricane intensity in 36 h, and that rapid weakening continues to be reflected in the latest intensity forecast. While sheared puffs of deep convection may continue for a subsequent day or two, eventually Leslie is likely to lose the necessary convective organization to be classified as a tropical cyclone. The NHC forecast continues to show Leslie becoming post-tropical by the end of the weekend, though this could occur sooner than forecast given the proximity of very dry environmental air and high shear affecting the system. Leslie continues to move northwestward, estimated at 315/7 kt this evening. The track forecast is more straightforward, with Leslie rounding the western edge of a subtropical ridge to its east, resulting in a gradual turn northward and then northeastward over the forecast period. With that said, there has been a notable westward and poleward shift in the guidance this cycle, and the NHC track forecast was moved in that direction, but not as far as the latest TVCN and HCCA consensus aids. FORECAST POSITIONS AND MAX WINDS INIT 10/0300Z 22.6N 49.3W 90 KT 105 MPH 12H 10/1200Z 23.3N 49.9W 100 KT 115 MPH 24H 11/0000Z 24.4N 50.4W 80 KT 90 MPH 36H 11/1200Z 26.0N 50.1W 55 KT 65 MPH 48H 12/0000Z 28.4N 48.4W 45 KT 50 MPH 60H 12/1200Z 30.7N 45.5W 45 KT 50 MPH 72H 13/0000Z 33.0N 41.6W 45 KT 50 MPH 96H 14/0000Z 36.0N 31.0W 40 KT 45 MPH...POST-TROPICAL 120H 15/0000Z 37.1N 21.9W 30 KT 35 MPH...POST-TROP/REMNT LOW $$ Forecaster Papin
