000 WTNT43 KNHC 250856 TCDAT3 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