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#875505 (Received by flhurricane at: 10:40 AM 21.Sep.2016) TCDAT3 TROPICAL STORM LISA DISCUSSION NUMBER 8 NWS NATIONAL HURRICANE CENTER MIAMI FL AL132016 1100 AM AST WED SEP 21 2016 The cloud pattern of Lisa has not changed much since the previous advisory. A 0911 UTC SSMIS image suggested that the low-level center was located on the western edge of the central convection. The 12Z Dvorak Data-T numbers from SAB and TAFB decreased and a partial ASCAT-B pass from 1115 UTC only showed 30-35 kt winds in the northeastern quadrant. However, the initial intensity is held at 45 kt given the lack of clear evidence of weakening and in agreement with the the latest Dvorak CI numbers of T3.0/45 kt. There is only a small opportunity for the cyclone to strengthen before the shear increases even further in 24 to 36 hours. Weakening is expected after that time, and later in the period, as the mid-level environment becomes quite dry, the cyclone should weaken to a remnant low. The new NHC intensity forecast is similar to the previous one and is near the middle of the guidance in the first 36 hours and then is near or below the weaker LGEM solution after that time. The initial motion estimate is a somewhat uncertain 320/07, given the lack of confidence in the location of the center. Lisa will move northwestward during the next 72 hours into a weakness in the subtropical ridge over the eastern Atlantic, and then recurve into the mid-latitude westerlies on days 4 and 5. The global models are in generally good agreement on this scenario, with the ECMWF lying on the left side of the guidance cluster and the GFS shifting to the right this cycle. The new NHC track forecast is an update of the previous one but has been adjusted for the initial position and motion. This forecast is near a blend of the latest GFS and ECMWF tracks and is well to the left of the GFDL and HWRF models, which lie nearly 200 n mi east of the rest of the guidance at days 3 and 4. FORECAST POSITIONS AND MAX WINDS INIT 21/1500Z 18.0N 32.5W 45 KT 50 MPH 12H 22/0000Z 18.6N 33.4W 50 KT 60 MPH 24H 22/1200Z 19.7N 34.9W 45 KT 50 MPH 36H 23/0000Z 20.9N 36.5W 45 KT 50 MPH 48H 23/1200Z 22.3N 38.0W 40 KT 45 MPH 72H 24/1200Z 25.0N 41.0W 30 KT 35 MPH 96H 25/1200Z 28.5N 43.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 26/1200Z 34.0N 41.0W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Brennan |