517 
 WTNT43 KNHC 260845
 TCDAT3
  
 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