000
WTNT44 KNHC 241438
TCDAT4
TROPICAL STORM LISA DISCUSSION NUMBER  15
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL142010
1100 AM AST FRI SEP 24 2010
 
SATELLITE IMAGERY DURING THE PAST 6 HOURS INDICATES THAT DEEP
CONVECTION HAS CONTINUED TO DEVELOP AND NOW WRAPS ABOUT
THREE-FOURTHS OF THE WAY AROUND THE CENTER. CLOUD TOPS HAVE COOLED
TO NEAR -80C JUST NORTH OF THE CENTER...AND VISIBLE AND MICROWAVE
IMAGERY HAVE BEEN HINTING OF A BANDING-EYE FEATURE TRYING TO FORM.
THE INITIAL INTENSITY OF 40 KT IS BASED ON A BLEND OF SATELLITE
INTENSITY ESTIMATES OF T2.5/35 KT FROM TAFB...TAFB AODT ESTIMATES
OF T3.4/53 KT...AND UW-CIMSS 3-HR AVERAGE ADT ESTIMATES OF T3.4/53
KT. A 24/1146Z ASCAT OVERPASS SHOWED 33-KT WINDS EAST OF THE
CENTER...BUT THERE IS PROBABLY SOME UNDER SAMPLING OCCURRING DUE TO
THE VERY SMALL SIZE OF THE INNER-CORE CIRCULATION. THEREFORE...IT
IS POSSIBLE THAT LISA COULD BE A LITTLE STRONGER THAN ANALYZED.
 
SATELLITE MICROWAVE AND CONVENTIONAL FIXES INDICATE LISA IS NOW
MOVING AT ABOUT 360/06. THE GENERAL MOTION SHOULD BE NORTHWARD FOR
THE NEXT 24-36 HOURS AS LISA MOVES AROUND THE WESTERN PERIPHERY OF
THE SAHARAN SUBTROPICAL RIDGE. AS LISA MOVES OVER COLDER WATER AND
ENCOUNTERS MODERATE TO STRONG WESTERLY SHEAR AHEAD OF A SHORTWAVE
TROUGH...THE LOW-LEVEL AND UPPER-LEVEL CIRCULATIONS ARE EXPECTED TO
DECOUPLE. AS A RESULT... THE LOW-LEVEL CIRCULATION IS FORECAST TO
MOVE NORTH-NORTHWESTWARD OR NORTHWESTWARD AS A REMNANT LOW PRESSURE
SYSTEM IN 48-72 HOURS. THE NHC FORECAST TRACK IS ADJUSTED RIGHTWARD
TOWARD THE MODEL CONSENSUS...BUT IS STILL ALONG THE LEFT SIDE OF
THE GUIDANCE ENVELOPE.
 
WHILE IT IS POSSIBLE THAT LISA COULD INTENSIFY MORE THAN FORECAST
BASED ON RECENT SATELLITE TRENDS...THIS CYCLONE HAS HAD A LONG
HISTORY OF APPEARING TO GET STRONGER...ONLY TO HAVE THE CYCLONE
INGEST DRY AIR NEARBY THAT HAS CAUSED THE INNER-CORE CONVECTION TO
WEAKEN AND SOMETIMES EVEN DISSIPATE. BY 24 HOURS...LISA IS FORECAST
TO MOVE OVER COOLER SSTS BELOW 26C AND ENCOUNTER VERTICAL WIND
SHEAR OF 20-40 KT. THESE NEGATIVE FACTORS SHOULD INDUCE STEADY
WEAKENING AND POSSIBLE DISSIPATION IN 96-120 HOURS. THE OFFICIAL
INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY AND IS A
LITTLE LOWER THAN ALL OF THE OBJECTIVE INTENSITY FORECAST GUIDANCE.
 

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      24/1500Z 18.9N  27.8W    40 KT
 12HR VT     25/0000Z 19.8N  27.9W    40 KT
 24HR VT     25/1200Z 21.2N  28.2W    35 KT
 36HR VT     26/0000Z 22.9N  28.6W    35 KT
 48HR VT     26/1200Z 24.3N  29.0W    30 KT
 72HR VT     27/1200Z 26.5N  29.8W    25 KT...POST-TROP/REMNT LOW
 96HR VT     28/1200Z 28.0N  30.5W    20 KT...POST-TROP/REMNT LOW
120HR VT     29/1200Z...DISSIPATED
 
$$
FORECASTER STEWART