Hurricane JIMENA

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HURRICANE JIMENA DISCUSSION NUMBER  12
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP132009
800 AM PDT MON AUG 31 2009

THE EYE HAS BEEN COMING AND GOING ON INFRARED IMAGERY AND...BASED ON
MICROWAVE IMAGERY...APPEARS TO BE A LITTLE LARGER THAN IT WAS
YESTERDAY.  THE MICROWAVE IMAGES EARLIER THIS MORNING ALSO
SUGGESTED THAT JIMENA MAY HAVE UNDERGONE AN EYEWALL REPLACEMENT. 
DVORAK SUBJECTIVE AND OBJECTIVE DATA T-NUMBERS HAVE DECREASED A
LITTLE OVER THE PAST 12 HOURS...SO JIMENA MAY HAVE WEAKENED
SLIGHTLY.  HOWEVER...I WILL HOLD THE CURRENT INTENSITY AT 125 KT
UNTIL AIR FORCE RECONNAISSANCE INVESTIGATES THE HURRICANE A LITTLE
LATER TODAY AND GIVES US SOME IN SITU MEASUREMENTS.  THE WATERS ARE
WARM ALONG THE PROJECTED TRACK...BUT NOT QUITE AS WARM AFTER ABOUT
24 HOURS AND WITH REDUCED OCEANIC HEAT CONTENT.  ALSO...THE GLOBAL
MODELS INDICATE SOME INCREASE IN SOUTHWESTERLY SHEAR IN 24-48
HOURS.  HOWEVER NONE OF THESE FACTOR ARE LIKELY TO PREVENT JIMENA
FROM REMAINING A MAJOR HURRICANE UP TO LANDFALL.  THE OFFICIAL
INTENSITY FORECAST IS A BLEND OF THE SHIPS AND LGEM MODELS...WHICH
HISTORICALLY HAVE BEEN OUR BEST INTENSITY GUIDANCE.

INITIAL MOTION IS ESTIMATED TO BE 315/7.  THE STEERING SCENARIO
REMAINS MORE OR LESS THE SAME.  JIMENA IS LIKELY TO MOVE BETWEEN A
MID-LEVEL RIDGE OVER NORTHWESTERN MEXICO AND A MID- TO UPPER-LEVEL
CYCLONE JUST TO THE WEST OF THE BAJA PENINSULA.  THE DYNAMICAL
TRACK PREDICTION MODELS ARE IN REASONABLY GOOD AGREEMENT OVER THE
NEXT 48 HOURS...WITH THE EXCEPTION OF THE U.K. MET. OFFICE GLOBAL
AND THE LOW-RESOLUTION GFS ENSEMBLE MEAN WHICH ARE CONSIDERED
WESTERN OUTLIERS AT THIS TIME.  IN FACT...THE MEAN OF THE
HIGHER-RESOLUTION PARALLEL RUN OF THE GFS IS FAIRLY CLOSE TO THE
MIDDLE OF THE GUIDANCE ENVELOPE.  THE OFFICIAL FORECAST IS FAIRLY
SIMILAR TO THE PREVIOUS ONE AND NOT FAR FROM THE MODEL CONSENSUS.

BASED ON THE FORECAST...THE GOVERNMENT OF MEXICO HAS ISSUED A
HURRICANE WARNING FOR A PORTION OF THE SOUTHERN BAJA CALIFORNIA
PENINSULA AND A HURRICANE WATCH FARTHER NORTH ALONG THE BAJA
PENINSULA.

INTERESTS IN THE WARNING AREA ARE REMINDED...DO NOT FORECAST ON THE
EXACT FORECAST TRACK.  A HURRICANE IS NOT A POINT AND DANGEROUS
IMPACTS EXTEND SOME DISTANCE FROM THE CENTER.  MOREOVER...TRACK
FORECAST ERRORS CAN EASILY BE 50 TO 75 MILES IN THE 24 TO 36 HOURS
TIME FRAME.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      31/1500Z 18.0N 108.3W   125 KT
 12HR VT     01/0000Z 19.1N 109.2W   125 KT
 24HR VT     01/1200Z 21.0N 110.3W   125 KT
 36HR VT     02/0000Z 23.0N 111.2W   115 KT
 48HR VT     02/1200Z 25.0N 111.9W    95 KT...INLAND
 72HR VT     03/1200Z 27.6N 112.9W    50 KT...INLAND
 96HR VT     04/1200Z 29.0N 113.5W    30 KT...INLAND
120HR VT     05/1200Z 30.0N 114.0W    25 KT...OVER WATER
 
$$
FORECASTER PASCH
 
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