045 
 WTPZ42 KNHC 040231
 TCDEP2
 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