[Tropical] Tropical Cyclone Discussion

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WTNT43 KNHC 221455
TCDAT3
TROPICAL STORM LISA DISCUSSION NUMBER  13
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 AM EDT WED SEP 22 2004

VISIBLE IMAGERY THIS MORNING SHOWS A SMALL...MOSTLY EXPOSED
CIRCULATION TO THE NORTH OR NORTHEAST OF THE CORE CONVECTION.  THE
INITIAL INTENSITY IS LOWERED BASED ON THE MOST RECENT QUIKSCAT PASS
AND DVORAK CLASSIFICATIONS.  LISA IS BEING AFFECTED BY THE LARGER
AREA OF DISTURBED WEATHER TO ITS EAST-SOUTHEAST...AS THE INITIAL
MOTION IS NOW 250/5.  IT ALSO IS SUFFERING FROM EASTERLY SHEAR FROM
THE SOUTH SIDE OF AN UPPER-LEVEL RIDGE BETWEEN LISA AND KARL.  ALL
IN ALL...THIS IS NOT A SCENARIO THAT WOULD FAVOR INTENSIFICATION IN
THE SHORT TERM...AND IN FACT...LISA COULD GET ABSORBED BY THE
EASTERN DISTURBANCE OVER THE NEXT COUPLE OF DAYS.  THE OFFICIAL
FORECAST WILL CALL FOR LITTLE CHANGE IN STRENGTH FOR 72
HOURS...FOLLOWED BY SLOW STRENGTHENING AS INDICATED BY BOTH THE
SHIPS AND GFDL MODELS.  HOWEVER...IT SHOULD BE NOTED THAT BOTH THE
GFS AND UKMET DROP AN UPPER TROUGH DEEP INTO THE CENTRAL ATLANTIC
BY DAY FIVE...AND THIS WOULD TEND TO PROVIDE AN UNFAVORABLE
ENVIRONMENT FOR EITHER LISA OR THE DISTURBANCE BEHIND IT.

NUMERICAL MODELS CONTINUE TO SHOW A WIDE RANGE OF POSSIBLE TRACKS
FOR LISA.  HOWEVER...THE INTERACTION PREDICTED FOR THE PAST TWO
DAYS BY THE GFDL IS NOW BEGINNING...AND SO CONSIDERABLE WEIGHT HAS
BEEN PLACED ON THIS MODEL.  LISA IS EXPECTED TO SLOW AND TURN MORE
SOUTHWARD AROUND THE EASTERN DISTURBANCE.  IF LISA SURVIVES...IN
THIS SCENARIO IT WOULD THEN TURN NORTHWESTWARD AROUND THE BACK SIDE
OF THE DISTURBANCE.  SUCH A SCENARIO BECOMES MORE LIKELY IF LISA'S
CIRCULATION REMAINS MOSTLY EXPOSED...WHILE A STRONGER CYCLONE WOULD
BE MORE LIKELY TO CONTINUE A SIMPLER WESTWARD TRACK IN RESPONSE TO
THE UPPER-LEVEL EASTERLIES.

FORECASTER FRANKLIN

FORECAST POSITIONS AND MAX WINDS

INITIAL      22/1500Z 13.9N  41.3W    45 KT
 12HR VT     23/0000Z 13.8N  41.7W    45 KT
 24HR VT     23/1200Z 13.2N  42.3W    45 KT
 36HR VT     24/0000Z 13.0N  42.5W    45 KT
 48HR VT     24/1200Z 13.0N  43.0W    45 KT
 72HR VT     25/1200Z 14.0N  44.5W    50 KT
 96HR VT     26/1200Z 16.0N  45.5W    60 KT
120HR VT     27/1200Z 20.0N  48.0W    70 KT


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