WTNT43 KNHC 220238 RRA

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=