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#875441 (Received by flhurricane at: 4:52 PM 20.Sep.2016) TCDAT3 TROPICAL STORM LISA DISCUSSION NUMBER 5 NWS NATIONAL HURRICANE CENTER MIAMI FL AL132016 500 PM AST TUE SEP 20 2016 During the past six hours, a central dense overcast (CDO) feature has developed over and to the east of Lisa`s low-level center. The upper-level outflow has also improved, albeit elongated northeast- to-southwest. The initial intensity has been increased to 40 kt, which is a blend of a Dvorak satellite intensity estimate of T2.5/35 kt from TAFB, a UW-CIMSS ADT values of T2.9/43 kt, and a 1611Z AMSU estimate of 44 kt. The initial motion estimate is 315/10 kt. Lisa has made a jog to the right of the previous forecast track and model guidance, which is most likely due to the center reforming closer to the strongest convection. Other than shifting the forecast track to the right of the previous advisory track to account for the more eastward initial position, the forecast rationale remains unchanged. The latest NHC model guidance continues to indicate a steady northwestward motion for the next four days toward a break in the subtropical ridge between 30W-40W longitude. On day 5, Lisa is expected to move northward as the ridge erodes eastward. The new NHC forecast track lies down the middle of the tightly packed guidance envelope through day 4, and then follows a blend of the ECMWF and HWRF models on day 5 since those models maintain the cyclone longer. Lisa has another 36 hours or so to strengthen some more before the large-scale environment becomes very unfavorable, which will be characterized by southwesterly vertical wind shear of 25-30 kt, drier and more stable air, and SSTs less than 27 deg C. It is possible that Lisa could end up being a little stronger between the 24- and 36-hour forecast periods. By 48 hours, however, steady weakening is expected to ensue, with Lisa becoming a remnant low pressure system by 120 hours. The intensity forecast closely follows the intensity consensus model IVCN. FORECAST POSITIONS AND MAX WINDS INIT 20/2100Z 16.4N 31.0W 40 KT 45 MPH 12H 21/0600Z 17.2N 32.1W 45 KT 50 MPH 24H 21/1800Z 18.1N 33.6W 50 KT 60 MPH 36H 22/0600Z 19.0N 35.0W 50 KT 60 MPH 48H 22/1800Z 20.0N 36.5W 45 KT 50 MPH 72H 23/1800Z 22.7N 39.2W 35 KT 40 MPH 96H 24/1800Z 25.2N 42.0W 30 KT 35 MPH 120H 25/1800Z 29.2N 44.0W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Stewart |