[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT43 KNHC 290830
TCDAT3
TROPICAL STORM LISA DISCUSSION NUMBER  40
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT WED SEP 29 2004

A REPORT AT 6Z OF 34 KT FROM SHIP FQFL...ABOUT 175 NM NORTH-
NORTHEAST OF THE CENTER OF LISA...GIVES ADDITIONAL SUPPORT TO SOME
OF THE STRONGER WINDS IN THE EARLIER QUIKSCAT PASS AT 21Z...AND
SUGGESTS THAT LISA HAD WINDS OF ABOUT 60 KT AT THAT TIME.  THE
INITIAL INTENSITY IS INCREASED TO 60 KT ON THIS BASIS.  ALTHOUGH THE
SYSTEM REMAINS SHEARED WITH A SHARPLY ELONGATED LOW-LEVEL
CIRCULATION...DEEP CONVECTION IS NOW INCREASING NORTH...RATHER THAN
NORTHEAST OF THE CENTER AND THE UPPER-LEVEL CIRRUS IS BEGINNING TO
PUSH OUTWARD IN THE NORTHWEST QUADRANT.  THIS IS CONSISTENT WITH
THE FORECAST CUTOFF OF AN UPPER-LEVEL LOW TO THE SOUTHWEST OF
LISA...WHICH SHOULD ACT TO REDUCE THE SHEAR AND ALLOW LISA TO
BECOME A HURRICANE OVER THE NEXT 24 HOURS BEFORE THE SYSTEM MOVES
OVER COOLER WATERS.

THE INITIAL MOTION ESTIMATE IS 010/11.  A TURN TO THE
NORTH-NORTHWEST AROUND THE UPPER CUTOFF LOW IS EXPECTED DURING THE
NEXT 24 HOURS...BEFORE LISA IS RELEASED FROM THE LOW AND ENCOUNTERS
SOUTHWESTERLIES AHEAD OF THE REMNANTS OF HURRICANE JEANNE.  SOME
GUIDANCE SUGGESTS THAT AS LISA WEAKENS OVER COOLER WATERS IT COULD
MERGE WITH THE EXTRATROPICAL REMNANTS OF JEANNE...BUT I WILL CARRY
POSITIONS OUT TO 120 HOURS IN CASE THE MERGER DOES NOT OCCUR.  NONE
OF THE TRACK GUIDANCE HAS SHOWN THE EAST OF NORTH MOTION OBSERVED
OVER THE PAST FEW HOURS...AND SO MY TRACK IS A LITTLE TO THE RIGHT
OF THE GUIDANCE ENVELOPE FOR THE FIRST 24 HOURS OR SO.  AFTER
THAT...THE OFFICIAL FORECAST IS JUST SLIGHTLY EAST OF THE PREVIOUS
TRACK AND IS CLOSE TO THE DYNAMICAL MODEL CONSENSUS.  IT IS PERHAPS
WORTH NOTING THAT THE GFDL HAS A TRACK A COUPLE HUNDRED MILES TO
THE WEST OF MINE AND KEEPS LISA STRONGER LONGER.

FORECASTER FRANKLIN

FORECAST POSITIONS AND MAX WINDS

INITIAL      29/0900Z 28.0N  46.1W    60 KT
 12HR VT     29/1800Z 29.5N  46.2W    60 KT
 24HR VT     30/0600Z 31.3N  47.0W    65 KT
 36HR VT     30/1800Z 33.0N  48.0W    65 KT
 48HR VT     01/0600Z 35.0N  48.5W    60 KT
 72HR VT     02/0600Z 38.0N  46.5W    55 KT
 96HR VT     03/0600Z 42.0N  40.0W    50 KT...EXTRATROPICAL
120HR VT     04/0600Z 43.5N  30.0W    45 KT...EXTRATROPICAL


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