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Hurricane JIMENA (Text)

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HURRICANE JIMENA DISCUSSION NUMBER   4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP132009
800 AM PDT SAT AUG 29 2009
 
JIMENA HAS BEEN UNDERGOING RAPID INTENSIFICATION OVERNIGHT AND
RECENTLY A SMALL EYE SURROUNDED BY VERY STRONG THUNDERSTORMS HAS
BECOME APPARENT ON VISIBLE SATELLITE IMAGERY. A SPECIAL DVORAK
CLASSIFICATION AT 1345 UTC FROM TAFB INDICATED THAT THE SYSTEM WAS
NEAR 65 KT...AND THE LATEST OBJECTIVE T-NUMBERS ARE SUGGESTING 70
TO 75 KT. THE INITIAL INTENSITY IS RAISED TO 70 KT FOR THIS
ADVISORY. THE LARGE-SCALE ENVIRONMENT APPEARS EXTREMELY FAVORABLE
FOR CONTINUED RAPID STRENGTHENING...WITH VERY WARM SSTS OVER
30C...VERY HIGH MID-LEVEL HUMIDITY AND LOW SHEAR. THE SHIPS RAPID
INTENSIFICATION INDEX IS FORECASTING A 95 PERCENT CHANCE OF A 35 KT
INCREASE DURING THE NEXT 24 HOURS...THE HIGHEST VALUE I HAVE EVER
SEEN. IN ADDITION...ALL GUIDANCE SHOWS THIS SYSTEM BECOMING EITHER
A CATEGORY THREE OR FOUR HURRICANE. THUS...THE OFFICIAL FORECAST
WILL SHOW CONTINUED RAPID STRENGTHENING...SHOWING A 35-KT INCREASE
FROM THE 1200 UTC SYNOPTIC INTENSITY OF 60 KT. SSTS DECREASE IN THE
LONG-RANGE...AND WEAKENING IS SHOWN AFTER DAY 3. 

THE INITIAL MOTION IS 285/08. WEAK MID-LEVEL RIDGING OVER MEXICO
SHOULD PROVIDE THE STEERING CURRENTS OVER THE NEXT SEVERAL DAYS FOR
JIMENA...WITH THE HURRICANE LIKELY MAKING A NORTHWESTWARD TURN IN A
DAY OR TWO AS IT ROUNDS THE SOUTHWESTERN PERIPHERY OF THE RIDGE.
HOWEVER...THERE ARE SOME BIG DISCREPANCIES IN HOW MUCH THAT RIDGE
WEAKENS DUE TO A MID- TO UPPER-LEVEL TROUGH OVER BAJA CALIFORNIA.
THE GFDL/HWRF SHOW ENOUGH OF A WEAKNESS IN THE RIDGE TO TURN JIMENA
NORTHWEST AND NORTH-NORTHWEST BY TOMORROW...POISING A SIGNIFICANT
THREAT TO BAJA CALIFORNIA OR WESTERN MEXICO. ALL OF THE OTHER
GUIDANCE MAINTAIN ENOUGH OF A RIDGE BETWEEN THAT TROUGH AND JIMENA
TO CONTINUE A WEST-NORTHWEST TO NORTHWESTWARD MOTION OF THE
HURRICANE FOR SEVERAL DAYS. IN PREVIOUS YEARS...THE HWRF/GFDL HAVE
HAD AN EASTWARD BIAS FOR THESE TYPES OF SYSTEMS...AND THEIR CURRENT
FORECASTS HAVE BEEN GRADUALLY SHIFTING WESTWARD WITH TIME. THE NHC
FORECAST IS SHIFTED WESTWARD...BUT IS NOT AS FAR WEST AS THE MODEL
CONSENSUS. IT WOULD NOT BE SURPRISING TO SEE FURTHER WESTWARD
ADJUSTMENTS LATER ON...ESPECIALLY IF THE REGIONAL HURRICANE MODELS
COME INTO BETTER AGREEMENT WITH THE GLOBAL MODELS.

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      29/1500Z 14.3N 103.2W    70 KT
 12HR VT     30/0000Z 14.6N 104.4W    85 KT
 24HR VT     30/1200Z 15.0N 105.7W    95 KT
 36HR VT     31/0000Z 15.6N 106.9W   105 KT
 48HR VT     31/1200Z 16.7N 108.2W   115 KT
 72HR VT     01/1200Z 19.5N 111.0W   115 KT
 96HR VT     02/1200Z 22.5N 114.0W    90 KT
120HR VT     03/1200Z 25.0N 117.0W    55 KT
 
$$
FORECASTER BLAKE
 
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