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| #875594 (Received by flhurricane at: 10:52 AM 22.Sep.2016) TCDAT3 TROPICAL STORM LISA DISCUSSION NUMBER 12 NWS NATIONAL HURRICANE CENTER MIAMI FL AL132016 1100 AM AST THU SEP 22 2016 An ASCAT-A pass from 1138Z showed that the center of Lisa is located near the southwestern edge of an area of bursting deep convection. The ASCAT data showed a cluster of 40-45 kt winds north of the center, so the initial intensity is set to 45 kt for this advisory, which is also in agreement with the latest Dvorak current intensity estimates of T3.0/45 kt from TAFB and SAB. The restrengthening appears to have occurred despite the shear increasing to 30-35 kt based on the SHIPS model analyses and satellite analyses from UW-CIMSS, and the upper-level outflow has improved somewhat during the past few hours. However, the separation between the convection and the low-level center appears to be increasing, and Lisa will be moving into a region of even stronger southwesterly shear in the next 24 hours, which should result in weakening. The shear is forecast to relax late in the period, but it is unlikely that Lisa will be able to recover and the cyclone is forecast to become a remnant low in 3 to 4 days. This is in agreement with the global models, which show the system decaying by that time. The new NHC intensity forecast is a little higher than the previous one given the higher initial intensity, and is closest to the statistical- dynamical SHIPS and LGEM models. Based on the ASCAT data and earlier microwave fixes, my best estimate of the initial motion is 310/06, as the cyclone appears to have slowed down some during the past few hours. The track forecast reasoning remains the same, however, with Lisa expected to move northwestward into a break in the subtropical ridge for the next 48 hours. After that time, Lisa or its remnants should recurve ahead of a large mid-latitude trough. The new NHC track forecast is an update of the previous one through 72 hours and has been shifted a bit to the right at days 4 and 5 following the latest model guidance trends. There is a fair bit of along-track spread in the guidance late in the period, with the ECMWF much faster than the GFS and UKMET. The NHC forecast favors the slower solution, in agreement with the latest guidance from the Ocean Prediction Center. The initial and forecast 34-kt wind radii were adjusted based on the above-mentioned ASCAT data. FORECAST POSITIONS AND MAX WINDS INIT 22/1500Z 20.0N 34.0W 45 KT 50 MPH 12H 23/0000Z 21.1N 35.1W 45 KT 50 MPH 24H 23/1200Z 22.5N 36.4W 40 KT 45 MPH 36H 24/0000Z 23.8N 37.6W 35 KT 40 MPH 48H 24/1200Z 25.0N 39.0W 30 KT 35 MPH 72H 25/1200Z 28.0N 41.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 96H 26/1200Z 32.0N 39.5W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 27/1200Z 35.5N 37.0W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Brennan |
