Tropical Storm HENRIETTE

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TROPICAL STORM HENRIETTE DISCUSSION NUMBER  13
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP112007
200 PM PDT SUN SEP 02 2007
 
VISIBLE SATELLITE IMAGERY INDICATES THAT HENRIETTE IS TRYING TO FORM
A BANDING EYE.  HOWEVER...DVORAK INTENSITY ESTIMATES REMAIN AT 55 KT
AND THE INITIAL INTENSITY IS HELD AT 60 KT FOR THIS ADVISORY.
 
HENRIETTE IS LOCATED IN A SEEMINGLY IDEAL ENVIRONMENT FOR
STRENGTHENING...AND GLOBAL MODELS ALL AGREE THAT THE CYCLONE WILL
REMAIN BENEATH A WELL-DEFINED UPPER-LEVEL ANTICYCLONE AND WITHIN A
LOW SHEAR ENVIRONMENT. SSTS ARE EXPECTED TO BE SUFFICIENTLY WARM
FOR THE NEXT DAY OR SO. DESPITE THIS ENVIRONMENT...THE INTENSITY
FORECAST IS MUDDIED BY THE FACT THAT HENRIETTE IS A VERY SMALL
CYCLONE CAPABLE OF RAPID INTENSITY FLUCTUATIONS...BOTH UP AND DOWN.
MOREOVER...THE NEW OFFICIAL FORECAST TRACK IS A LITTLE CLOSER TO
THE MAINLAND COAST OF MEXICO. SUCH A SMALL CYCLONE COULD UNDERGO
RAPID INTENSIFICATION IF THE CENTER STAYS FAR ENOUGH OFFSHORE.
LIKEWISE...IT COULD BE EASILY DISRUPTED BY INTERACTION WITH THE
COAST OF MAINLAND MEXICO SHOULD IT MOVE A LITTLE RIGHT OF THE
OFFICIAL FORECAST TRACK. THE OFFICIAL FORECAST ASSUMES HENRIETTE
WILL REMAIN FAR ENOUGH OFFSHORE DURING THE FIRST 36 HOURS FOR
INTENSIFICATION TO OCCUR. BEYOND 72 HOURS...HENRIETTE IS EXPECTED
TO MOVE ACROSS THE BAJA PENINSULA INTO NORTHWESTERN MAINLAND MEXICO
WHERE IT SHOULD DISSIPATE. MOISTURE FROM THIS SYSTEM COULD MAKE IT
INTO PORTIONS OF THE SOUTHWESTERN UNITED STATES IN 4 OR 5 DAYS.
 
VISIBLE IMAGERY INDICATES THAT HENRIETTE HAS BEEN MOVING SLOWER THAN
PREVIOUSLY THOUGHT...WITH AN INITIAL MOTION ESTIMATED AT 295/4.
THE OVERALL FORECAST PHILOSOPHY IS UNCHANGED.  GLOBAL MODELS SHOW A
MID-LEVEL RIDGE CURRENTLY OVER THE SOUTHWESTERN UNITED STATES
SHIFTING EASTWARD OVER THE NEXT COUPLE OF DAYS AHEAD OF A LARGE
MIDDLE- TO UPPER-LEVEL TROUGH APPROACHING THE WEST COAST OF THE
UNITED STATES.  THIS PATTERN SHOULD ALLOW HENRIETTE TO GRADUALLY
TURN NORTHWESTWARD THEN NORTHWARD.  IN GENERAL...MOST OF THE
GUIDANCE HAS TRENDED EASTWARD WITH THE MOST SIGNIFICANT EASTWARD
SHIFT BEING IN THE UKMET.  THE GFDL REMAINS THE EASTERNMOST
OUTLIER...BUT THIS SOLUTION CANNOT BE IGNORED GIVEN ITS PERFORMANCE
LAST YEAR DURING JOHN AND LANE...TWO HURRICANES THAT SIMILARLY
PARALLELED THE COAST OF MAINLAND MEXICO.   THE OFFICIAL FORECAST IS
AGAIN ADJUSTED A LITTLE TO THE RIGHT OF THE PREVIOUS ONE GIVEN THE
RECENT MODEL TRENDS AND THE GFDL TRACK.
 
HENRIETTE'S CURRENT SLOW MOTION DELAYS THE NEED FOR WATCHES OVER
PORTIONS OF THE SOUTHERN BAJA PENINSULA...BUT THEY MAY BE REQUIRED
LATER TODAY.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      02/2100Z 18.6N 106.6W    60 KT
 12HR VT     03/0600Z 19.1N 107.4W    70 KT
 24HR VT     03/1800Z 20.1N 108.6W    75 KT
 36HR VT     04/0600Z 21.3N 109.7W    85 KT
 48HR VT     04/1800Z 22.6N 110.6W    75 KT
 72HR VT     05/1800Z 25.5N 111.5W    65 KT...INLAND OVER BAJA
 96HR VT     06/1800Z 30.5N 111.5W    40 KT...INLAND 
120HR VT     07/1800Z...DISSIPATED
 
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FORECASTER RHOME
 
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