239 
 WTPZ42 KNHC 060835
 TCDEP2
 TROPICAL STORM KRISTY DISCUSSION NUMBER  30
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP122006
 200 AM PDT WED SEP 06 2006
  
 CONVECTION ASSOCIATED WITH KRISTY HAS SHOWN A MARKED DECREASE THIS
 MORNING...WITH ONLY A FEW ISOLATED CLOUD TOPS COLDER THAN -60C IN A
 BAND WELL TO THE SOUTHWEST OF THE CENTER.  SATELLITE INTENSITY
 ESTIMATES ARE 35 AND 30 KT FROM TAFB AND SAB RESPECTIVELY...AND
 THERE WAS A 47 KT AMSU ESTIMATE AT 0153 UTC.  GIVEN THE DECREASING
 CONVECTION IT IS TEMPTING TO DOWNGRADE KRISTY TO A DEPRESSION...BUT
 THAT SHOULD PROBABLY WAIT A FEW MORE HOURS TO MAKE SURE THE
 CONVECTION DOES NOT COME BACK.  THUS...THE INITIAL INTENSITY
 REMAINS 35 KT.
 
 THE INITIAL MOTION IS 285/12...AND THE MOTION OVER THE PAST FEW
 HOURS MAY BE A BIT FASTER.  KRISTY IS ON THE SOUTH SIDE OF A
 LOW/MID-LEVEL RIDGE...WHICH LARGE-SCALE MODELS FORECAST WILL WEAKEN
 DURING THE FORECAST PERIOD AS A BROAD MID/UPPER-LEVEL TROUGH
 DEVELOPS OVER THE NORTHEASTERN PACIFIC.  THIS EVOLUTION SHOULD KEEP
 KRISTY MOVING GENERALLY WEST-NORTHWESTWARD TO WESTWARD WITH A
 GRADUAL DECREASE IN FORWARD SPEED.  ALL THE TRACK GUIDANCE AGREES
 WITH THIS SCENARIO...SAVE FOR THE BAMD AND LBAR WHICH TURN KRISTY
 NORTHWARD THROUGH THE WEAKENING RIDGE.  SINCE IT APPEARS UNLIKELY
 THAT KRISTY WILL BE STRONG ENOUGH TO MAKE SUCH A TURN...THE NEW
 FORECAST TRACK FOLLOWS THE BALANCE OF THE GUIDANCE WESTWARD.  THE
 NEW TRACK IS A LITTLE SOUTH OF AND SLOWER THAN THE MODEL CONSENSUS.
 
 THE SHIPS...GFDL...AND FSU SUPERENSEMBLE MODELS ALL CALL FOR KRISTY
 TO MAINTAIN TROPICAL STORM STRENGTH OR EVEN INTENSIFY SLIGHTLY
 DURING THE NEXT 72 HR.  GIVEN THE CURRENT CONVECTIVE TRENDS AND
 MARGINAL SEA SURFACE TEMPERATURES NEAR 26C...THIS MIGHT BE A LITTLE
 OPTIMISTIC.  THE NEW INTENSITY FORECAST ASSUMES THAT THE CONVECTION
 WILL RETURN AND CALLS FOR SLIGHT STRENGTHENING FOR 24 HR OR SO TO
 40 KT...LESS THAN THE GUIDANCE AND THE PREVIOUS FORECAST.  AFTER 72
 HR...INCREASING SOUTHWESTERLY VERTICAL SHEAR IS FORECAST BY THE
 LARGE-SCALE MODELS...WHICH SHOULD CAUSE KRISTY TO WEAKEN AND
 EVENTUALLY DISSIPATE.  IF THE CONVECTION DOES NOT COME BACK IN THE
 NEXT 6-12 HR...THEN KRISTY COULD WEAKEN TO A REMNANT LOW IN THE
 NEXT DAY OR SO INSTEAD OF STRENGTHENING.
 
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      06/0900Z 17.3N 125.2W    35 KT
  12HR VT     06/1800Z 17.7N 127.0W    35 KT
  24HR VT     07/0600Z 18.1N 129.2W    40 KT
  36HR VT     07/1800Z 18.2N 130.8W    40 KT
  48HR VT     08/0600Z 18.2N 132.3W    40 KT
  72HR VT     09/0600Z 18.5N 135.0W    35 KT
  96HR VT     10/0600Z 19.0N 138.0W    30 KT
 120HR VT     11/0600Z 19.0N 141.0W    25 KT...DISSIPATING
  
 $$
 FORECASTER BEVEN