Hurricane RINA

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HURRICANE RINA DISCUSSION NUMBER   8
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL182011
500 AM EDT TUE OCT 25 2011
 
RINA IS MAINTAINING A RATHER SYMMETRICAL CDO FEATURE WITH THE CENTER
LOCATED ABOUT IN THE MIDDLE OF A MASS OF VERY COLD CLOUD TOPS...BUT
AN EYE IS NOT YET DISCERNIBLE ON GEOSTATIONARY IMAGERY.  AN AIR
FORCE RECONNAISSANCE PLANE HAS BEEN INVESTIGATING THE HURRICANE
EARLY THIS MORNING.  THE HIGHEST UNFLAGGED SFMR WIND SPEED MEASURED
BY THE AIRCRAFT WAS 84 KT...THE PEAK FLIGHT-LEVEL WINDS WERE 89
KT...AND A GPS DROPSONDE MEASUREMENT IN THE WESTERN EYEWALL
SUPPORTED A SURFACE WIND SPEED OF AT LEAST 82 KT.  THE AIRCRAFT
DATA INDICATE THAT THIS SYSTEM IS MORE EFFECTIVE THAN USUAL IN
TRANSPORTING STRONG WINDS ALOFT TO THE SURFACE...WHICH IS
CONSISTENT WITH THE VIGOROUS DEEP CONVECTION OCCURRING NEAR THE
CENTER.  THE INITIAL WIND SPEED IS INCREASED TO 85 KT FOR THIS
ADVISORY.  RINA CONTINUES TO EXHIBIT STRONG UPPER-LEVEL OUTFLOW...
PARTICULARLY OVER THE NORTHERN SEMICIRCLE AND WILL CONTINUE TO
TRAVERSE WATERS OF HIGH OCEANIC HEAT CONTENT FOR THE NEXT COUPLE OF
DAYS.  ADDITIONAL STRENGTHENING SEEMS LIKELY UNTIL INCREASING
SOUTH-SOUTHWESTERLY SHEAR HALTS THE INTENSIFICATION PROCESS...WHICH
IS EXPECTED TO OCCUR IN ABOUT 48 HOURS.  THE OFFICIAL WIND SPEED
FORECAST IS ABOUT THE SAME AS IN THE PREVIOUS ADVISORY ALBEIT A
LITTLE LOWER NEAR THE END OF THE PERIOD.  THIS IS IN REASONABLE
AGREEMENT WITH THE CONSENSUS OF THE INTENSITY FORECAST MODELS.  IT
SHOULD BE NOTED THAT THE NORMALLY RELIABLE ECMWF MODEL SHOWS RINA
DISSIPATING OVER NORTHERN YUCATAN.
 
AIRCRAFT CENTER FIXES INDICATE THAT RINA CONTINUES TO MOVE VERY
SLOWLY OR ABOUT 290/3.  GLOBAL MODEL GUIDANCE SHOWS THAT THE WEAK
MID-TROPOSPHERIC RIDGE CURRENTLY TO THE NORTH OF RINA WILL
ESSENTIALLY DISSIPATE IN A COUPLE OF DAYS AND A BROAD TROUGH WILL
MOVE OVER THE U.S. EAST COAST NEAR THE END OF THE FORECAST PERIOD.
THESE CHANGES IN THE STEERING CURRENTS SHOULD CAUSE THE HURRICANE
TO TURN TOWARD THE NORTHWEST AND THEN NORTH IN 2 TO 3 DAYS.  BY
DAYS 4-5 THE CYCLONE IS EXPECTED TO TURN EASTWARD...BUT SINCE THE
SYSTEM SHOULD BE WEAKENING IT IS NOT EXPECTED TO FULLY RESPOND TO
THE MID-TROPOSPHERIC STEERING FLOW.  THE OFFICIAL FORECAST CALLS
FOR ONLY A VERY SLOW EASTWARD MOTION NEAR THE END OF THE FORECAST
PERIOD...AND IS SIMILAR TO THE GFS FORECAST AS WELL AS TO THE
PREVIOUS ADVISORY TRACK.  CONVERSELY...THE GFDL MODEL MAINTAINS
RINA AS A HURRICANE AND SHOWS A MUCH FASTER MOTION TOWARD THE
EAST-NORTHEAST IN THE LATTER PART OF THE FORECAST PERIOD.  HOWEVER
SINCE THIS IS NOW THE ONLY DYNAMICAL MODEL SHOWING SUCH BEHAVIOR...
IT IS AN OUTLIER THAT IS BEING DISREGARDED AT THIS TIME.
 
GIVEN THE LARGE SPREAD IN THE MODEL SOLUTIONS IN THE EXTENDED
RANGE...THE CONFIDENCE IN THE LATTER PART OF THE TRACK FORECAST
REMAINS LOW.
  
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  25/0900Z 17.3N  83.6W   85 KT 100 MPH
 12H  25/1800Z 17.4N  84.3W   90 KT 105 MPH
 24H  26/0600Z 17.8N  85.1W   95 KT 110 MPH
 36H  26/1800Z 18.3N  86.0W  100 KT 115 MPH
 48H  27/0600Z 19.3N  86.7W  100 KT 115 MPH
 72H  28/0600Z 21.5N  87.0W   80 KT  90 MPH...INLAND
 96H  29/0600Z 22.5N  85.0W   65 KT  75 MPH
120H  30/0600Z 22.5N  84.0W   55 KT  65 MPH...INLAND
 
$$
FORECASTER PASCH/LANDSEA
 
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