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Tropical Storm LISA Forecast Discussion Number 14
2016-09-23 04:38:56| National Hurricane Center (Atlantic)
Issued at 1100 PM AST THU SEP 22 2016 000 WTNT43 KNHC 230238 TCDAT3 TROPICAL STORM LISA DISCUSSION NUMBER 14 NWS NATIONAL HURRICANE CENTER MIAMI FL AL132016 1100 PM AST THU SEP 22 2016 Lisa continues to struggle in the face of strong deep-layer shear. Although the cyclone continues to pulsate convection, several microwave passes between 1900 and 2100 UTC indicate that the center has become somewhat more removed from the deepest convection since this afternoon. The initial intensity has been lowered to 40 kt, in line with decreased Dvorak estimates from TAFB and SAB. A 2344 UTC ASCAT-B pass missed the center of Lisa, but showed that 35 kt winds are present 100-150 nm NE of the presumed center. Lisa is forecast to remain in a high shear and increasingly dry environment, so further weakening seems inevitable. The main question is how quickly will the deep convection cease to exist. The GFS and HWRF both show mid- to upper-level dry air cutting over the circulation in about 36 to 48 hours, suggesting a complete lack of deep convection in those models at that time. The official forecast now calls for Lisa to become post tropical within 48 hours, before being absorbed by an approaching front after 96 hours. There is little change to the track forecast reasoning overall. Lisa continues to move toward the northwest, or 320 degrees, at a rather uncertain 8 kt. A lack of microwave or scatterometer data over the center since 2100 UTC has made the center difficult to locate and introduces some uncertainty to the forecast. Regardless, Lisa should continue moving northwestward around a low- to mid-level ridge, located east of the Azores, before recurving ahead of an approaching front. The first 48 hours of the forecast are near a consensus of the GFS and ECMWF models. The 72 and 96 hour points incorporate guidance from the Ocean Prediction Center. FORECAST POSITIONS AND MAX WINDS INIT 23/0300Z 21.3N 35.2W 40 KT 45 MPH 12H 23/1200Z 22.4N 36.3W 35 KT 40 MPH 24H 24/0000Z 23.6N 37.8W 30 KT 35 MPH 36H 24/1200Z 24.7N 39.3W 30 KT 35 MPH 48H 25/0000Z 26.2N 40.7W 30 KT 35 MPH...POST-TROP/REMNT LOW 72H 26/0000Z 30.5N 41.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 96H 27/0000Z 35.5N 37.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 28/0000Z...ABSORBED $$ Forecaster Beven/Zelinsky
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