[Tropical] Tropical Cyclone Discussion

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WTNT43 KNHC 252054
TCDAT3

HURRICANE RINA DISCUSSION NUMBER  10
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL182011
500 PM EDT TUE OCT 25 2011

DATA FROM THE AIR FORCE HURRICANE HUNTER AIRCRAFT INDICATE THAT RINA
HAS INTENSIFIED A LITTLE THIS AFTERNOON. THE INITIAL
INTENSITY IS RAISED TO 95 KT BASED ON A PEAK SFMR WIND OF 94 KT AND
700-MB FLIGHT-LEVEL WIND MAXIMUM OF 106 KT. THE LATEST CENTRAL
PRESSURE MEASURED FROM THE PLANE WAS 970 MB...FALLING A LITTLE OVER
THE PAST FEW HOURS. THE ENVIRONMENT APPEARS FAVORABLE FOR SOME
ADDITIONAL INTENSIFICATION DURING THE NEXT DAY OR TWO AS THE
CYCLONE MOVES OVER VERY WARM WATERS IN A REGION OF LOW WIND SHEAR.
THE OFFICIAL FORECAST SHOWS A BROAD PEAK AT 100 KT FROM 12 TO 48
HOURS...A LITTLE ABOVE THE SHIPS AND LGEM MODELS. AFTER THAT
TIME...RINA WILL BE MOVING INTO A REGION OF INCREASING VERTICAL
SHEAR...WHICH SHOULD RESULT IN WEAKENING. THE NEW NHC FORECAST IS
SIMILAR TO THE PREVIOUS ONE AT DAYS 3 THROUGH 5...FOLLOWING THE
SHIPS AND LGEM. HOWEVER...IF RINA MOVES FARTHER INLAND OVER THE
YUCATAN PENINSULA THAN EXPECTED...IT COULD BE WEAKER THAN FORECAST
IN 2 OR 3 DAYS.

AIRCRAFT FIXES INDICATE THAT RINA HAS JOGGED TOWARD THE LEFT OVER
THE PAST FEW HOURS...WITH THE INITIAL MOTION NOW 270/04. THE TRACK
FORECAST REASONING REMAINS UNCHANGED IN THE SHORT TERM...AS RINA
SHOULD BEGIN TO TURN POLEWARD AROUND THE WESTERN EDGE OF THE
SUBTROPICAL RIDGE. THE TRACK GUIDANCE REMAINS IN GOOD AGREEMENT ON
THIS SCENARIO...AND ONLY A SLIGHT WESTWARD ADJUSTMENT WAS MADE TO
THE OFFICIAL FORECAST THROUGH 48 HOURS. AFTER THE CYCLONE PASSES BY
THE YUCATAN PENINSULA...SIGNIFICANT SPREAD DEVELOPS IN THE
GUIDANCE. THE TRACK AND INTENSITY FORECASTS ARE CLOSELY LINKED LATE
IN THE PERIOD. ON ONE EXTREME...THE ECMWF WEAKENS RINA AND
DISSIPATES IT OVER THE CENTRAL GULF OF MEXICO AFTER 72 HOURS...
WHILE THE GFS AND HWRF TAKE A STRONGER CYCLONE QUICKLY TOWARD THE
NORTHEAST AHEAD OF A BROAD MID/UPPER-LEVEL TROUGH. MUCH OF THE REST
OF THE GUIDANCE LIES BETWEEN THESE TWO CAMPS...BUT THE OVERALL
TREND IS NORTH OF THE PREVIOUS NHC FORECAST. THE NHC FORECAST HAS
BEEN ADJUSTED IN THAT DIRECTION...BUT A SLOW MOTION IS SHOWN AT
DAYS 4 AND 5 DUE TO THE LARGE SPREAD IN THE GUIDANCE. NEEDLESS TO
SAY...THE CONFIDENCE IN THE LATTER PART OF THE TRACK FORECAST
REMAINS VERY LOW.


FORECAST POSITIONS AND MAX WINDS

INIT  25/2100Z 17.4N  84.3W   95 KT 110 MPH
 12H  26/0600Z 17.5N  85.2W  100 KT 115 MPH
 24H  26/1800Z 18.3N  86.1W  100 KT 115 MPH
 36H  27/0600Z 19.4N  86.8W  100 KT 115 MPH
 48H  27/1800Z 20.8N  86.9W  100 KT 115 MPH
 72H  28/1800Z 22.5N  86.0W   80 KT  90 MPH
 96H  29/1800Z 23.5N  84.0W   60 KT  70 MPH
120H  30/1800Z 23.5N  82.5W   45 KT  50 MPH

$$
FORECASTER BRENNAN



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