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Hurricane JIMENA (Text)

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HURRICANE JIMENA DISCUSSION NUMBER  13
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP132009
200 PM PDT MON AUG 31 2009
 
THE AIR FORCE RESERVE HURRICANE HUNTERS HAVE JUST COMPLETED THEIR
MISSION IN JIMENA...AND FOUND THAT THE HURRICANE WAS STRONGER THAN
PREVIOUSLY ESTIMATED. PEAK 700 MB FLIGHT-LEVEL WINDS WERE 149 KT
AND THE MAXIMUM SFMR-MEASURED SURFACE WINDS WERE 132 KT OVER THE
NORTHEAST QUADRANT. THE SFMR ALSO MEASURED 128 KT IN THE NORTHWEST
EYEWALL AND 125 KT IN THE SOUTHWEST PART OF THE EYEWALL. A MINIMUM
CENTRAL PRESSURE OF 931 MB WAS MEASURED BY DROPSONDE. THE CURRENT
INTENSITY IS ADJUSTED UPWARD TO 135 KT...AT THE VERY HIGH END OF
CATEGORY 4 STATUS. FLUCTUATIONS IN STRENGTH ARE LIKELY DURING THE
NEXT DAY OR SO DUE TO INNER CORE EVENTS...PRIMARILY EYEWALL
REPLACEMENTS. HOWEVER THE SHIPS MODEL INDICATES A GRADUAL DECREASE
IN OCEANIC HEAT CONTENT AND SOME INCREASE IN WEST-SOUTHWESTERLY
SHEAR DURING THE NEXT 36 HOURS. HOWEVER THESE ENVIRONMENTAL
INFLUENCES SHOULD NOT PREVENT JIMENA FROM MAINTAINING MAJOR
HURRICANE STRENGTH PRIOR TO LANDFALL. THE OFFICIAL INTENSITY
FORECAST IS A BLEND OF THE SHIPS AND LGEM GUIDANCE.
 
AFTER WOBBLING WEST-NORTHWESTWARD A FEW HOURS AGO...THE MOTION IS
BACK TO NORTHWEST OR 315/9.  THERE HAS BEEN LITTLE CHANGE TO THE
TRACK FORECAST PHILOSOPHY.  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 U.K. MET.
OFFICE GLOBAL MODEL...LIKE THE ECMWF GLOBAL MODEL...PREVIOUSLY
WESTERN OUTLIERS...HAVE SHIFTED EASTWARD AND ARE NOW IN GENERAL
AGREEMENT WITH THE OTHER DYNAMICAL MODELS.  HOWEVER THE U.K. AND
ECMWF ARE STILL SOMEWHAT SLOWER THAN MOST OF THE GUIDANCE.  THE
OFFICIAL FORECAST IS SIMILAR TO THE PREVIOUS ONE AND ABOUT IN THE
MIDDLE OF THE DYNAMICAL TRACK MODEL SUITE.

NO CHANGES TO THE WATCHES AND WARNINGS ARE NECESSARY AT THIS TIME.
INTERESTS IN THE WARNING AREA SHOULD BE ADVISED THAT STRONG WINDS
WILL PRECEDE THE ARRIVAL OF THE CENTER BY SEVERAL HOURS...SO
PREPARATIONS NEED TO BE COMPLETED AS EARLY AS POSSIBLE. 
ALSO...INTERESTS IN THE WARNING AREA ARE REMINDED...NOT TO FOCUS
ON THE EXACT FORECAST TRACK.  A HURRICANE IS NOT A POINT...AND
DANGEROUS IMPACTS EXTEND SOME DISTANCE FROM THE CENTER.  IN
FACT...THE AIR FORCE RECONNAISSANCE OBSERVATIONS SHOW THAT JIMENA
IS LARGER THAN PREVIOUS ESTIMATED.  MOREOVER...TRACK FORECAST
ERRORS CAN EASILY BE 50 TO 75 MILES IN THE 24 TO 36 HOUR TIME
FRAME.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      31/2100Z 18.5N 109.2W   135 KT
 12HR VT     01/0600Z 19.6N 110.1W   130 KT
 24HR VT     01/1800Z 21.6N 111.1W   125 KT
 36HR VT     02/0600Z 23.6N 111.8W   115 KT
 48HR VT     02/1800Z 25.5N 112.2W    85 KT
 72HR VT     03/1800Z 27.8N 112.7W    50 KT...INLAND
 96HR VT     04/1800Z 29.5N 113.0W    50 KT...OVER WATER
120HR VT     05/1800Z 31.0N 113.0W    30 KT...INLAND
 
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FORECASTER PASCH
 
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