Hurricane JIMENA

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HURRICANE JIMENA DISCUSSION NUMBER   6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP132009
800 PM PDT SAT AUG 29 2009

WHILE THE SMALL EYE SEEN EARLIER IN VISIBLE AND INFRARED IMAGERY IS
NOT APPARENT AT THIS TIME...SSM/I DATA AT 0106 UTC SHOWS IT IS
STILL PRESENT UNDER THE CENTRAL DENSE OVERCAST.  THE MICROWAVE DATA
ALSO SHOWED AN OUTER BAND WRAPPING AROUND THE CENTRAL CONVECTION
THAT MAY BE THE PRECURSOR OF AN OUTER EYEWALL.  SINCE THE EYE IS
NOT APPARENT IN CONVENTIONAL IMAGERY...IT IS UNCLEAR IF THE
HURRICANE IS STILL INTENSIFYING.  THUS...THE INITIAL INTENSITY
REMAINS 90 KT IN AGREEMENT WITH SATELLITE INTENSITY ESTIMATES FROM
TAFB AND SAB.  HOWEVER...THIS COULD BE CONSERVATIVE.
 
JIMENA HAS TURNED A LITTLE BIT TO THE RIGHT...WITH THE INITIAL
MOTION NOW 305/10.  THE HURRICANE IS ON THE SOUTHWEST SIDE OF A
DEEP-LAYER RIDGE OVER CENTRAL MEXICO...WITH WATER VAPOR IMAGERY
SHOWING A MID/UPPER-LEVEL LOW OVER THE GULF OF CALIFORNIA NEAR
27N111W.  THE GLOBAL MODELS FORECAST THE MEXICAN RIDGE TO BUILD
NORTHWESTWARD AND PUSH THE WEAKENING LOW INTO THE PACIFIC...WHICH
WOULD ALLOW JIMENA TO CONTINUE ON A GENERALLY NORTHWESTWARD TRACK
FOR THE NEXT SEVERAL DAYS.  ON THE OTHER HAND...THE GFDL AND HWRF
KEEP THE LOW STRONG ENOUGH AND FAR ENOUGH TO THE EAST TO TURN
JIMENA NORTHWARD WITH A LANDFALL IN WESTERN MEXICO.  AT THIS
TIME...IT IS DIFFICULT TO DETERMINE WHICH SCENARIO WILL PLAY OUT. 
HOWEVER...THE GFDL HAS PERFORMED WELL IN SIMILAR PAST SITUATIONS
AND THUS CANNOT BE RULED OUT.  ALSO...MANY OF THE GLOBAL MODELS
FORECAST JIMENA TO SHEAR APART IN THE LATER PART OF THE FORECAST
PERIOD...WHICH MAY NOT HAPPEN TO SUCH A STRONG AND DEEP HURRICANE. 
THE GUIDANCE ENVELOPE HAS SHIFTED TO THE EAST SINCE THE PREVIOUS
ADVISORY...AND BASED ON THIS AND THE CURRENT MOTION THE NEW
FORECAST TRACK IS SHIFTED TO THE EAST AS WELL.  THE NEW TRACK IS
NEAR THE THE GUNA...TVCN...AND TVCC CONSENSUS MODELS...AS WELL AS
NEAR THE GFS DYNAMICAL MODEL.

CONDITIONS APPEAR FAVORABLE FOR SIGNIFICANT STRENGTHENING DURING THE
NEXT 48 HR...AS JIMENA WILL BE OVER VERY WARM SEA SURFACE
TEMPERATURES IN A LIGHT VERTICAL WIND SHEAR ENVIRONMENT.  THE ONLY
POTENTIAL LIMITING FACTOR AT THE MOMENT IS THE POSSIBILITY OF
EYEWALL REPLACEMENT CYCLES.  ALL GUIDANCE FORECASTS THE SYSTEM TO
BECOME A MAJOR HURRICANE DURING THIS TIME...AND THE NEW INTENSITY
FORECAST FOLLOWS THAT WITH A PEAK INTENSITY OF 125 KT IN 36 HR.  IT
IS POSSIBLE DEPENDING ON THE TIMING OF THE EYEWALL REPLACEMENT
CYCLES THAT JIMENA COULD GET STRONGER THAN THAT.  ON THE FORECAST
TRACK...JIMENA WOULD REACH COOLER SSTS AFTER 48 HR...WHICH SHOULD
CAUSE THE STORM TO WEAKEN.  THE LONGER-TERM INTENSITY FORECAST IS
LOW CONFIDENCE...AS THE POSSIBILITY OF LAND INTERACTION AND
INCREASED VERTICAL WIND SHEAR AFTER 72 HR MAKE THE FORECAST MORE
PROBLEMATIC.

THE GFDL AND HWRF MODELS FORECAST WINDS NEAR HURRICANE FORCE AT CABO
CORRIENTES IN ABOUT 36 HR...AND IF THESE MODEL FORECASTS APPEAR TO
BE VERIFYING WATCHES OR WARNING COULD BE NEEDED LATER TONIGHT OR
SUNDAY.  IN ADDITION...THE NEW FORECAST TRACK INCREASES THE THREAT
TO THE SOUTHERN BAJA CALIFORNIA PENINSULA.  INTERESTS IN SOUTHERN
BAJA AND WESTERN MEXICO SHOULD MONITOR THE PROGRESS OF JIMENA.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      30/0300Z 15.8N 105.1W    90 KT
 12HR VT     30/1200Z 16.5N 106.2W   105 KT
 24HR VT     31/0000Z 17.3N 107.4W   120 KT
 36HR VT     31/1200Z 18.2N 108.4W   125 KT
 48HR VT     01/0000Z 19.5N 109.6W   125 KT
 72HR VT     02/0000Z 22.5N 112.0W   110 KT
 96HR VT     03/0000Z 25.0N 114.0W    75 KT
120HR VT     04/0000Z 26.5N 117.0W    45 KT
 
$$
FORECASTER BEVEN
 
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