Tropical Storm KRISTY

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TROPICAL STORM KRISTY DISCUSSION NUMBER  21
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP122006
800 PM PDT SUN SEP 03 2006

RECENT INFRARED IMAGERY OF KRISTY SHOWS THE CONVECTIVE FLARE UP
INDICATED IN THE EARLIER ADVISORY PACKAGE IS NOW DIMINISHING AS
CLOUD TOP TEMPERATURES ARE -50 DEGREES CELSIUS OR LESS IN THE
WESTERN QUADRANT.  PREVIOUS QUIKSCAT WIND VECTORS AND RECENT
NESDIS-CIRA AMSU INTENSITY ESTIMATES HOLD KRISTY AT MINIMAL
TROPICAL STORM STRENGTH.  HOWEVER...DVORAK CLASSIFICATION NUMBERS
FROM TAFB...SAB AND AFWA ARE SLIGHTLY LOWER FOR INTENSITY
ESTIMATES.  FOR THIS ADVISORY...KRISTY WILL REMAIN AT MINIMAL
TROPICAL STORM STRENGTH BASED ON THE AMSU INTENSITY ESTIMATES...BUT
KRISTY WILL LIKELY DROP BACK TO A DEPRESSION WITHIN THE NEXT 12
HOURS.

MOST INTENSITY GUIDANCE AGREES THAT KRISTY WILL REMAIN NEAR TROPICAL
STORM STRENGTH OVER THE NEXT 36 HOURS.  HOWEVER...EASTERLY
SHEAR OF 20 KTS WILL CONTINUE TO IMPACT THE SYSTEM DURING THE EARLY
PART OF THE FORECAST WHICH SHOULD INHIBIT ANY POSSIBLE
STRENGTHENING...AND COULD BRING ABOUT WEAKENING.  LATER ON IN THE
FORECAST PERIOD...THE SYSTEM MOVES INTO PROGRESSIVELY COOLER WATERS
AND IT IS LIKELY TO WEAKEN TO NON-TROPICAL CYCLONE STATUS.  THE
OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS ONE...AND
ALSO FAIRLY CONSISTENT WITH THE LATEST RUN OF THE GFDL MODEL. 

THE PRESENT MOTION OF KRISTY IS ESTIMATED AT 260/2 WHICH SUGGESTS
THAT THE SYSTEM HAS FINALLY BEGAN TO SLIDE BACK TOWARD THE WEST. 
ALL MODELS INDICATE A BUILDING RIDGE TO THE NORTH WITH KRISTY
REMAINING ALONG THE SOUTHERN EXTENT OF THE RIDGE.  THIS SCENARIO
MOVES KRISTY BACK TOWARD THE WEST AT A SLOW PACE AND INCREASING
EASTERLIES DURING THE MIDDLE TIME PERIOD WILL ACCELERATE THE
CYCLONE IN A CONTINUED WESTWARD DIRECTION.  MOST MODEL GUIDANCE IS
IN GOOD AGREEMENT WITH THIS PROJECTED TRACK...AND THE OFFICIAL
FORECAST TRACK FOLLOWS THE MODEL CONSENSUS FAIRLY CLOSELY.  THIS IS
ALSO QUITE SIMILAR TO THE PREVIOUS NHC TRACK FORECAST.  

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      04/0300Z 17.8N 118.4W    35 KT
 12HR VT     04/1200Z 17.8N 118.7W    35 KT
 24HR VT     05/0000Z 17.8N 119.4W    30 KT
 36HR VT     05/1200Z 18.0N 120.7W    30 KT
 48HR VT     06/0000Z 18.4N 122.8W    25 KT...DISSIPATING
 72HR VT     07/0000Z 19.0N 127.0W    20 KT...REMNANT LOW
 96HR VT     08/0000Z...DISSIPATED
 
$$
FORECASTER SISKO/PASCH
 
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