Hurricane RINA

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HURRICANE RINA DISCUSSION NUMBER  12
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL182011
400 AM CDT WED OCT 26 2011
 
THE EYE CONTINUES TO BE OBSCURED ON GEOSTATIONARY IMAGERY AND THE
ORGANIZATION OF THE HURRICANE HAS CHANGED LITTLE OVER THE PAST
SEVERAL HOURS.  AN AIR FORCE HURRICANE HUNTER PLANE MEASURED PEAK
700 MB FLIGHT-LEVEL WINDS OF 104 KT AND MAXIMUM BELIEVABLE
SFMR-OBSERVED SURFACE WINDS OF NEAR 90 KT...AND THE INITIAL WIND
SPEED IS HELD AT 95 KT FOR THIS ADVISORY.  WATER VAPOR IMAGERY
CONTINUES TO DEPICT A WELL-DEFINED UPPER-LEVEL OUTFLOW PATTERN...
AND ANALYSES FROM UW/CIMSS SUGGEST THAT STRONG VERTICAL SHEAR HAS
NOT YET REACHED THE CORE OF THE HURRICANE.  THEREFORE...RINA STILL
HAS AN OPPORTUNITY TO INTENSIFY INTO A MAJOR HURRICANE BEFORE IT
REACHES THE YUCATAN PENINSULA.  IT SHOULD BE NOTED...HOWEVER...THAT
THE OCEANIC HEAT CONTENT BELOW THE CYCLONE SHOULD DIMINISH FROM
THIS POINT ONWARD...WHICH COULD BE A MITIGATING FACTOR FOR
STRENGTHENING.  THE OFFICIAL WIND SPEED FORECAST CONTINUES TO SHOW
RINA INTENSIFYING TO CATEGORY 3 STATUS LATER TODAY.  SOME DECREASE
IN STRENGTH IS LIKELY TO OCCUR DUE TO THE INTERACTION WITH THE
YUCATAN PENINSULA.  BY DAYS 2-3...WHEN RINA IS FORECAST TO MOVE
OVER THE SOUTHEASTERN GULF OF MEXICO...SIGNIFICANTLY HIGHER SHEAR
DUE TO STRONG UPPER-LEVEL WESTERLIES SHOULD CAUSE A WEAKENING
TREND.  THE OFFICIAL INTENSITY FORECAST IS CLOSE TO THE NUMERICAL
CONSENSUS AND SLIGHTLY ABOVE THE STATISTICAL-DYNAMICAL GUIDANCE.
 
CENTER FIXES FROM THE HURRICANE HUNTERS INDICATE THAT RINA CONTINUES
TO MOVE VERY SLOWLY...OR 280/4.  AS A MID-TROPOSPHERIC RIDGE TO THE
NORTH SHIFTS EASTWARD DURING THE NEXT DAY OR TWO...THE HURRICANE
SHOULD TURN NORTHWESTWARD AND THEN NORTHWARD.  THE TRACK GUIDANCE
MODELS ARE IN REASONABLY GOOD AGREEMENT ON THIS SCENARIO FOR THE
FIRST 48 HOURS OF THE FORECAST PERIOD.  BY 3 TO 4 DAYS...A LARGE
500 MB TROUGH MOVES TO THE U.S. EAST COAST...RESULTING IN A
STRENGTHENING MID-TROPOSPHERIC WEST-SOUTHWESTERLY FLOW OVER THE
EASTERN GULF OF MEXICO.  IF RINA WERE TO MAINTAIN HURRICANE
INTENSITY BEYOND DAY 3 OR SO...AND THEREFORE REMAIN A DEEP-LAYER
VORTEX...IT WOULD LIKELY ACCELERATE EAST-NORTHEASTWARD.  HOWEVER
THE MAJORITY OF THE GUIDANCE...AND THE OFFICIAL FORECAST...SHOW
SIGNIFICANT WEAKENING IN THAT TIME FRAME.  THEREFORE THE OFFICIAL
TRACK FORECAST...LIKE THE PREVIOUS ONE...SHOWS ONLY A SLOW EASTWARD
MOTION NEAR THE END OF THE PERIOD.  THIS IS REASONABLY CLOSE TO THE
LATEST GFS TRACK.  IT IS WORTH REPEATING THAT THERE IS GREAT
UNCERTAINTY AS TO WHERE RINA WILL BE LOCATED BY THE WEEKEND.
  
FORECAST POSITIONS AND MAX WINDS
 
INIT  26/0900Z 17.5N  85.2W   95 KT 110 MPH
 12H  26/1800Z 18.2N  85.8W  100 KT 115 MPH
 24H  27/0600Z 19.2N  86.6W  100 KT 115 MPH
 36H  27/1800Z 20.5N  87.0W  100 KT 115 MPH
 48H  28/0600Z 21.8N  86.6W   85 KT 100 MPH
 72H  29/0600Z 23.5N  84.5W   70 KT  80 MPH
 96H  30/0600Z 23.5N  83.0W   60 KT  70 MPH
120H  31/0600Z 23.5N  82.0W   45 KT  50 MPH
 
$$
FORECASTER PASCH
 
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