[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT43 KNHC 260828
TCDAT3
TROPICAL STORM LISA DISCUSSION NUMBER  28
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT SUN SEP 26 2004

THE LOCATION OF LISA IS SOMETHING OF A MYSTERY THIS MORNING...AS
DVORAK POSITION ESTIMATES AT 06Z FROM TAFB AND SAB WERE ABOUT 70
MILES APART...AND THE MOST RECENT MICROWAVE PASSES OVER THE CYCLONE
WERE NOT ESPECIALLY HELPFUL IN RESOLVING THE CENTER.  WHAT DATA DO
EXIST SUGGEST THAT THE CENTER MAY BE A LITTLE EAST OF THE PREVIOUS
TRACK...BUT GIVEN THE UNCERTAINTY I HAVE TRIED TO MAINTAIN
CONTINUITY WITH PREVIOUS ESTIMATES.  THE INITIAL MOTION IS
ESTIMATED TO BE 350/7.  POSITION UNCERTAINTY LEADS TO POOR
CONFIDENCE IN THE DVORAK INTENSITY ESTIMATES...AND THE INITIAL
INTENSITY IS HELD AT 45 KT IN ACCORD WITH THE QUIKSCAT PASS ABOUT 9
HOURS AGO. LISA IS SOMEWHERE NEAR THE NORTHWEST SIDE OF THE DEEP
CONVECTION.  WATER VAPOR WINDS AND IMAGERY SHOW A BAND OF
WESTERLIES OVER AND NORTHWEST OF THE STORM...AND THE GFS AND UKMET
SHOW THIS SHEAR SHOULD INCREASE OVER THE NEXT DAY OR TWO.  THE
INTENSITY FORECAST SHOWS LITTLE CHANGE OVER THIS PERIOD...AND IS A
LITTLE BELOW THE SHIPS AND GFDL GUIDANCE.  AFTER THAT...UPPER-LEVEL
RIDGING NEAR THE CYCLONE COULD ALLOW FOR SOME INTENSIFICATION.

LISA IS SOUTHEAST OF A DEEP TROUGH IN THE CENTRAL ATLANTIC...BUT THE
NOGAPS...UKMET...AND GFS ALL AGREE THAT THIS TROUGH SHOULD LIFT OUT
AND LEAVE LISA BEHIND.  THROUGH 72 HOURS THE TRACK MODEL GUIDANCE
IS PRETTY TIGHTLY CLUSTERED ON A TURN BACK TO THE NORTH-NORTHWEST
AS THE TROUGH LIFTS OUT.  NEAR THE END OF THE FORECAST PERIOD THERE
IS SOME DIVERGENCE IN THE GUIDANCE...WITH THE GFS AND NOGAPS
TURNING LISA NORTHEASTWARD AHEAD OF THE REMNANTS OF JEANNE...AND
THE UKMET AND GFDL STILL SHOWING A WESTWARD COMPONENT OF MOTION.
THE FSU SUPERENSEMBLE IS ALSO ON THE LEFT SIDE OF THE GUIDANCE
ENVELOPE.  THE OFFICIAL FORECAST IS TO THE RIGHT OF THE PREVIOUS
ADVISORY INITIALLY TO REFLECT THE RECENT FIXES AND APPARENT
MOTION...BUT IS ADJUSTED TO THE LEFT LATE IN FORECAST PERIOD TO BE
IN BETTER AGREEMENT WITH THE GFDL...SUPERENSEMBLE...AND GLOBAL
MODEL CONSENSUS.

FORECASTER FRANKLIN

FORECAST POSITIONS AND MAX WINDS

INITIAL      26/0900Z 18.4N  46.0W    45 KT
 12HR VT     26/1800Z 19.7N  46.3W    50 KT
 24HR VT     27/0600Z 21.4N  47.0W    50 KT
 36HR VT     27/1800Z 23.0N  47.7W    50 KT
 48HR VT     28/0600Z 24.5N  48.5W    55 KT
 72HR VT     29/0600Z 26.5N  50.0W    65 KT
 96HR VT     30/0600Z 29.0N  51.5W    65 KT
120HR VT     01/0600Z 32.0N  52.0W    65 KT


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