000 WTNT44 KNHC 250234 TCDAT4 HURRICANE LISA DISCUSSION NUMBER 18 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL142010 1100 PM AST FRI SEP 24 2010 RECENT SATELLITE IMAGES SHOW THAT THE EYE OF LISA HAS BECOME OBSCURED BY CIRRUS CLOUDS. HOWEVER...THE LATEST MICROWAVE PASS FROM AROUND 2300 UTC STILL SHOWED THAT AN EYE WAS PRESENT. SATELLITE ESTIMATES FROM TAFB AND SAB REMAIN 65 KT...THOUGH THE DATA-T VALUES WERE HIGHER...AND THE ADT FROM UW-CIMSS WAS 72 KT. THE INITIAL WINDS ARE SLIGHTLY INCREASED TO 70 KT AS A BLEND OF THESE DATA. LISA BASICALLY HAS THE OVERNIGHT HOURS LEFT FOR ANY STRENGTHENING UNTIL SOUTHWESTERLY SHEAR IS FORECAST BY ALL MODELS TO INCREASE. AS THE CYCLONE MOVES FARTHER NORTH...IT SHOULD ALSO INGEST DRIER AIR AND BE AFFECTED BY COOLER WATER TEMPERATURES. THUS STEADY WEAKENING IS FORECAST TO BEGIN TOMORROW...AND THE NHC FORECAST IS CLOSE TO THE SHIPS MODEL. SINCE LISA IS MUCH STRONGER THAN ANTICIPATED... REMNANT LOW STATUS IS NOT FORECAST UNTIL DAY 4...THOUGH IT WOULD NOT BE SURPRISING FOR IT TO HAPPEN SOONER DUE TO LISA REMAINING OVER SUB-26C WATERS. THE INITIAL MOTION CONTINUES TO BE 360/7. THERE HAS BEEN A SUBTLE SHIFT IN THE SYNOPTIC PATTERN FORECAST BY MOST OF THE MODELS DURING THE PAST SEVERAL CYCLES. A MID- TO UPPER-LEVEL TROUGH ALONG 35W IS ADVANCING CLOSER TO THE TROPICAL CYCLONE THAN PREVIOUSLY EXPECTED. CONSEQUENTLY...LESS RIDGING IS FORECAST TO BUILD TO THE NORTHEAST OF THE CYCLONE...WHICH WOULD ALLOW A MORE NORTHWARD TRACK RATHER THAN NORTHWESTWARD. AS LONG AS LISA REMAINS A VERTICALLY STACKED SYSTEM...A GENERAL MOTION TOWARD THE NORTH IS LIKELY...SIMILAR TO THE GFS AND ITS DEPENDENT MODEL SUITE. A NORTHWESTWARD TURN IS POSSIBLE BY THE END OF THE FORECAST PERIOD...BUT THE SYSTEM WILL EITHER BE A REMNANT LOW OR DISSIPATED BY THEN. THE NHC FORECAST IS SHIFTED TO THE RIGHT...AGAIN...BUT REMAINS TO THE WEST OF THE DYNAMICAL MODEL CONSENSUS. FORECAST POSITIONS AND MAX WINDS INITIAL 25/0300Z 20.7N 27.9W 70 KT 12HR VT 25/1200Z 21.9N 28.1W 75 KT 24HR VT 26/0000Z 23.7N 28.3W 65 KT 36HR VT 26/1200Z 25.0N 28.5W 55 KT 48HR VT 27/0000Z 26.4N 28.8W 45 KT 72HR VT 28/0000Z 28.5N 29.2W 30 KT 96HR VT 29/0000Z 30.5N 29.5W 25 KT...POST-TROP/REMNT LOW 120HR VT 30/0000Z...DISSIPATED $$ FORECASTER BLAKE