Tropical Storm HECTOR

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TROPICAL STORM HECTOR DISCUSSION NUMBER   3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP092006
200 AM PDT WED AUG 16 2006
 
THE CYCLONE HAS BEEN MAINTAINING DEEP CORE CONVECTION ALL EVENING
WITH INTERMITTENT BANDING...AND MICROWAVE PASSES SUGGEST THAT THE
CENTER IS JUST WITHIN THE CENTRAL CONVECTIVE MASS.  DVORAK
CLASSIFICATIONS AT 06Z WERE T2.5...35 KT...FROM ALL AGENCIES...WITH
DATA-T NUMBERS AS HIGH AS T3.5.  A QUIKSCAT PASS AT 01Z CAUGHT SOME
OF THE EASTERN SEMICIRCLE...AND THERE WERE A LOT OF 30 KT VECTORS
OUTSIDE THE HEAVY CONVECTION IN THE SOUTHEAST QUADRANT...WITH ONE
VECTOR NEAR 35 KT.  THE PASS MISSED THE DEEP CONVECTION AND LIKELY
THE STRONGEST WINDS...AND THE INITIAL INTENSITY IS THEREFORE SET TO
40 KT.  

IF THE CENTER IS WHERE I THINK IT IS...THE INITIAL MOTION IS A
LITTLE TO THE LEFT OF THE PREVIOUS TRACK...AT 270/13.  THERE HAS
BEEN ONLY A SLIGHT SOUTHWARD ADJUSTMENT OF THE PREVIOUS FORECAST
TRACK...AND THE BASIC SYNOPTIC REASONING IS UNCHANGED.  HECTOR IS
MOVING ALONG THE SOUTHWEST PERIPHERY OF THE SUBTROPICAL RIDGE THAT
EXTENDS WESTWARD FROM MEXICO.  GLOBAL MODELS ALL SHOW THE RIDGE
ERODED BY A MIDDLE- TO UPPER-LEVEL TROUGH NEAR 130W OVER THE NEXT
COUPLE OF DAYS...BUT DESPITE THIS EXHIBIT A FAIRLY LARGE SPREAD IN
THE FORECAST TRACKS OF HECTOR.  THE RIGHTMOST OUTLIERS ARE THE
NOGAPS AND GFNI...WHICH START OFF THE CYCLONE WITH AN IMMEDIATE
NORTHWESTWARD TRACK THAT SEEMS INCONSISTENT WITH THE CURRENT
MOTION.  ON THE LEFT IS THE UKMET...WHICH MARCHES HECTOR QUICKLY
OFF TO THE WEST AND SUBSEQUENTLY MISSES THE TROUGH.  THE INITIAL
WESTWARD MOTION IN THE UKMET ALSO SEEMS INCONSISTENT WITH PRESENT
TRENDS.  THIS LEAVES THE GFS AND GFDL IN THE MIDDLE...AND THE
OFFICIAL FORECAST IS CLOSE TO A BLEND OF THESE TWO MODELS THROUGH
96 HOURS.  NEAR THE END OF THE FORECAST PERIOD...AS HECTOR
PRESUMABLY WEAKENS...THE OFFICIAL FORECAST BENDS SLIGHTLY BACK TO
THE WEST IN ACCORD WITH THE SHALLOW BAM.

THERE STILL APPEARS TO BE SOME NORTHEASTERLY SHEAR OVER HECTOR...
ALTHOUGH THIS SHEAR IS FORECAST TO ABATE SOMEWHAT OVER THE NEXT DAY
OR SO.  HECTOR ALSO HAS ALMOST TWO DAYS OVER WARM WATERS.  THE GFDL
BRINGS HECTOR TO HURRICANE STRENGTH IN 48 HOURS...BUT THE SHIPS
GUIDANCE TOPS OUT AT 54 KT.  THE MAIN NEGATIVE PREDICTORS SEEM TO
BE ASSOCIATED WITH THE DISTRIBUTION OF COLD SATELLITE PIXEL
COUNTS...WHICH I CANNOT RECONCILE WITH WHAT LOOKS LIKE A DECENT
SATELLITE PRESENTATION.  GIVEN THE INTENSIFICATION OVERNIGHT...I AM
INCLINED TO FAVOR THE MORE AGGRESSIVE GFDL...AND NOTE THAT THE FSU
SUPERENSEMBLE ALSO BRINGS HECTOR TO HURRICANE STRENGTH IN 36 HOURS. 
BY 72 HOURS...HECTOR IS EXPECTED TO BE DECAYING OVER COOLER WATERS. 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      16/0900Z 13.1N 116.5W    40 KT
 12HR VT     16/1800Z 13.4N 118.3W    50 KT
 24HR VT     17/0600Z 14.0N 120.4W    60 KT
 36HR VT     17/1800Z 14.6N 122.4W    65 KT
 48HR VT     18/0600Z 15.5N 124.0W    70 KT
 72HR VT     19/0600Z 17.5N 127.5W    60 KT
 96HR VT     20/0600Z 19.5N 130.5W    45 KT
120HR VT     21/0600Z 21.0N 134.0W    30 KT
 
$$
FORECASTER FRANKLIN
 
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