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Tropical Storm LISA Forecast Discussion Number 10
2016-09-22 04:38:20| National Hurricane Center (Atlantic)
Issued at 1100 PM AST WED SEP 21 2016 000 WTNT43 KNHC 220238 TCDAT3 TROPICAL STORM LISA DISCUSSION NUMBER 10 NWS NATIONAL HURRICANE CENTER MIAMI FL AL132016 1100 PM AST WED SEP 21 2016 Lisa remains a sheared tropical cyclone. Deep convection has expanded in coverage this evening, but recent microwave imagery and ASCAT data indicate that the low-level center is located near the far western edge of the sharp gradient of cold cloud tops. The ASCAT pass did not cover much of the northeastern portion of the circulation, but it did detected a large area of 35 kt winds to the north and north-northeast of the center. Based on these data and satellite estimates of 35 and 45 kt, from SAB and TAFB respectively, the initial intensity remains 40 kt. Lisa is already located within an area of strong upper-level southwesterly winds to the southeast of a large upper-level low. During the next day or two the tropical storm is forecast to approach the cut-off low, which according to the SHIPS model will produce 30-40 kt of shear over Lisa. As a result, the tropical cyclone is expected to weaken and become a remnant low in about 3 days, and it could dissipate before the end of the foreast period. The new NHC intensity forecast essentially an update of the previous forecast and is in best agreement with the SHIPS and LGEM guidance. The microwave and ASCAT fixes suggest that Lisa is moving north-northwestward at about 6 kt, which is a little right of the previous forecasts. The cyclone is expected to move northwestward toward a weakness in the subtropical ridge currently between 30 and 40W. Later in the period, an amplifying mid- to upper-level trough over the western Atlantic should cause Lisa or its remnants to turn northward and recurve into the mid-latitude westerlies by day 5. The track guidance is in fairly good agreement, and only a small eastward adjustment was required during the first 72 hours. The updated track prediction is very close to the latest multi-model consensus. FORECAST POSITIONS AND MAX WINDS INIT 22/0300Z 19.2N 32.8W 40 KT 45 MPH 12H 22/1200Z 20.2N 33.8W 40 KT 45 MPH 24H 23/0000Z 21.6N 35.2W 35 KT 40 MPH 36H 23/1200Z 23.0N 36.5W 30 KT 35 MPH 48H 24/0000Z 24.3N 37.8W 30 KT 35 MPH 72H 25/0000Z 26.7N 40.5W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 26/0000Z 31.0N 41.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 27/0000Z 36.5N 37.5W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Brown
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