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| #904567 (Received by flhurricane at: 4:41 PM 25.Sep.2017) TCDAT4 Hurricane Lee Discussion Number 31 NWS National Hurricane Center Miami FL AL142017 500 PM AST Mon Sep 25 2017 Little Lee has weakened a little since the previous advisory. Over the past few hours, the previously clear 10-15 nmi diameter eye has become cloud filled, briefly becoming completely obscured. An average of the available intensity estimates from TAFB, SAB, UW-CIMSS ADT, UW-CIMSS SATCON, and NHC AODT is 75 kt, and that is initial intensity used for this advisory. Lee has completed a tight cyclonic loop and is now moving toward the west-southwest or 255/07 kt. A narrow mid-level ridge is expected to continue building to the north of Lee, forcing the small hurricane on a westward track for the next day or so. As an upper-level trough approaches from the west, the hurricane should turn toward the northwest on Wednesday and Thursday as the western portion of the subtropical ridge erodes. By Friday and beyond, Lee is forecast to get caught up in the brisk southwesterly flow ahead of the aforementioned trough and accelerate toward the northeast at forward speeds in excess of 20 kt. The official track forecast has been shifted westward closer to the consensus models through 96 h, and then lies close to the previous advisory track at 120 h. The modest southeasterly vertical wind shear that has been affecting Lee today is forecast by the GFS and ECMWF global models to abate shortly, and remain at less than 10 kt for the next 48 hours or so. As a result, some slight strengthening will be possible when the cyclone moves over warmer 28 deg C SSTs in 36-48 hours. Afterwards, increasing southwesterly vertical shear should induce slow but steady weakening, with Lee making the transition into an extratropical low by 120 h when the cyclone will be located over 18C-20C water temperatures and in a 30-40 kt sheared environment. Lee is forecast to remain a compact hurricane throughout the forecast period, with only a small increase in the 50- and 34-kt wind radii expected. FORECAST POSITIONS AND MAX WINDS INIT 25/2100Z 30.5N 50.6W 75 KT 85 MPH 12H 26/0600Z 30.4N 51.6W 75 KT 85 MPH 24H 26/1800Z 30.5N 53.4W 75 KT 85 MPH 36H 27/0600Z 31.0N 55.0W 80 KT 90 MPH 48H 27/1800Z 31.8N 55.6W 80 KT 90 MPH 72H 28/1800Z 34.5N 54.3W 75 KT 85 MPH 96H 29/1800Z 40.2N 47.5W 60 KT 70 MPH 120H 30/1800Z 46.9N 35.0W 50 KT 60 MPH...POST-TROP/EXTRATROP $$ Forecaster Stewart |
