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| #875420 (Received by flhurricane at: 11:07 AM 20.Sep.2016) TCDAT3 TROPICAL STORM LISA DISCUSSION NUMBER 4 NWS NATIONAL HURRICANE CENTER MIAMI FL AL132016 1100 AM AST TUE SEP 20 2016 The cloud pattern of the cyclone has steadily improved, with long curved bands having developed in the northern semicircle since the previous advisory. Although Dvorak satellite classifications from TAFB and SAB were 30 kt at 1200Z, recent UW-CIMSS ADT values have increased to 35 kt and AMSU intensity estimates range from 35-45 kt. Therefore the initial intensity has been increased to 35 kt, which is a compromise of these estimates, making the cyclone the eleventh named storm of the 2016 hurricane season. Visible satellite imagery indicates that Tropical Storm Lisa is now moving northwestward or 305/10 kt. Water vapor imagery and satellite-derived winds indicate that a large mid-latitude trough extends from near the Canary Islands southwestward into the tropics, which has created a break in the subtropical ridge along 30W-40W longitude. Lisa is forecast to move generally northwestward toward the break in the ridge for the next 4 days, followed by a northward turn as the cyclone moves around the western periphery of the ridge axis. The latest model guidance remains in good agreement on this track scenario, and the new NHC forecast track is just a little to the right of the previous advisory track, mainly to account for the more northward initial position, and lies close to the consensus model TVCN. Lisa has about 48 hours remaining to strengthen while the vertical wind shear and upper-level outflow pattern remain favorable, and sea-surface temperatures are above 27 deg C. However, a marginally moist mid-level environment and the large size of the cyclone are expected to prevent any rapid strengthening from occuring. After that time, the atmosphere is expected to become quite hostile, characterized by southwesterly shear of 25-30 kt and much drier mid-level air, resulting in steady weakening from 72-120 hours. Although the dynamical guidance continues to forecast some relaxation of the shear toward the end of the period, the cyclone will likely be too degraded to recover. The official intensity forecast is close to the SHIPS model through 48 hours, and then lies closer to the LGEM guidance after that. FORECAST POSITIONS AND MAX WINDS INIT 20/1500Z 15.3N 30.4W 35 KT 40 MPH 12H 21/0000Z 16.2N 31.5W 35 KT 40 MPH 24H 21/1200Z 17.3N 33.2W 40 KT 45 MPH 36H 22/0000Z 18.2N 35.0W 45 KT 50 MPH 48H 22/1200Z 19.1N 36.4W 50 KT 60 MPH 72H 23/1200Z 21.7N 39.0W 40 KT 45 MPH 96H 24/1200Z 24.5N 41.4W 30 KT 35 MPH 120H 25/1200Z 28.3N 43.6W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Stewart |
