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Hurricane RINA (Text)

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HURRICANE RINA DISCUSSION NUMBER  13
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL182011
1000 AM CDT WED OCT 26 2011

RINA HAS A SOMEWHAT RAGGED APPEARANCE THIS MORNING.  THE EYE IS NOT
APPARENT IN VISIBLE IMAGERY...AND DATA FROM THE RADARS AT BELIZE
CITY AND ON THE TRMM SATELLITE SUGGEST THE EYEWALL HAS LOST SOME
DEFINITION.  WHILE THE EYEWALL CLOUD TOP TEMPERATURES ARE COLDER
THAN -80C...THE OVERALL AMOUNT OF CONVECTION ASSOCIATED WITH THE
CYCLONE HAS DECREASED DURING THE PAST SEVERAL HOURS.  IN
ADDITION...THE OUTFLOW HAS DIMINISHED SINCE YESTERDAY...AND
ANALYSES FROM CIMSS AT THE UNIVERSITY OF WISCONSIN SUGGEST 15-20 KT
OF SOUTHERLY VERTICAL WIND SHEAR.  THE INITIAL INTENSITY IS KEPT AT
95 KT FOR THIS ADVISORY...BUT THIS COULD BE GENEROUS AND IT IS
QUITE POSSIBLE THAT THE NOAA HURRICANE HUNTER AIRCRAFT ABOUT TO
REACH THE STORM WILL FIND RINA HAS WEAKENED.
 
THE RECENT CENTER FIXES INDICATE THAT RINA HAS TURNED TOWARD THE
RIGHT DURING THE PAST SEVERAL HOURS WITH THE INITIAL MOTION NOW
290/4.  RINA IS CURRENTLY EMBEDDED IN A MID-LEVEL RIDGE...WITH A
STRONG LOW-LEVEL RIDGE NORTH OF THE HURRICANE AND AN UPPER-LEVEL
ANTICYCLONE TO ITS EAST OVER THE CENTRAL CARIBBEAN.  THE DYNAMICAL
MODELS FORECAST THE RIDGES TO THE NORTH AND WEST TO WEAKEN DURING
THE NEXT 48-72 HOURS AS A TROUGH IN THE WESTERLIES AND ASSOCIATED
COLD FRONT MOVE INTO THE GULF OF MEXICO.  THIS EVOLUTION SHOULD
CAUSE RINA TO GRADUALLY TURN NORTHWARD NEAR THE EAST COAST OF THE
YUCATAN PENINSULA.  THE TRACK GUIDANCE IS IN GOOD AGREEMENT ON THIS
PART OF THE FORECAST...AND THE NEW FORECAST TRACK IS SIMILAR TO THE
OLD ONE.  AFTER 72 HOURS...RINA IS EXPECTED TO MOVE INTO AN
ENVIRONMENT WHERE THE MID/UPPER-LEVEL FLOW TRIES TO STEER THE
CYCLONE NORTHEASTWARD WHILE THE LOW-LEVEL FLOW TRIES TO STEER IT
SOUTHWARD OR SOUTHWESTWARD.  THIS SHOULD CAUSE RINA TO SHEAR
APART...BUT THE MODELS DISAGREE ON WHEN THIS WILL HAPPEN AND THUS
ARE IN POOR AGREEMENT ON THE FORECAST TRACK.  THE ECMWF AND
CANADIAN WEAKEN RINA VERY QUICKLY AND KEEP THE LOW-LEVEL REMNANT
NEAR YUCATAN...WHILE THE GFDL FORECASTS A STRONGER CYCLONE TO CROSS
SOUTH FLORIDA INTO THE ATLANTIC.  THE OTHER MODELS ARE BETWEEN
THESE EXTREMES.  THE LATTER PORTION OF THE NEW FORECAST TRACK IS
SIMILAR TO THE PREVIOUS TRACK...IN BEST AGREEMENT WITH THE GFS AND
NOGAPS MODELS.  HOWEVER...THIS IS A LOW CONFIDENCE FORECAST.
 
SINCE THE OUTFLOW IS LESS IMPRESSIVE THAN 24 HOURS AGO AND THE SHEAR
IS FORECAST TO INCREASE FURTHER...IT APPEARS THAT RINA HAS RUN OUT
OF TIME TO INTENSIFY.  THE INTENSITY FORECAST NOW CALLS FOR THE
HURRICANE TO GRADUALLY WEAKEN DURING THE NEXT 12-24 HOURS...WITH A
FASTER WEAKENING AT 36-48 HOURS DUE TO LAND INTERACTION.  DUE TO
THE UNCERTAINTY OF JUST HOW QUICKLY RINA WILL SHEAR APART OVER THE
GULF OF MEXICO...THE FORECAST KEEPS RINA A HURRICANE THROUGH 72
HOURS AND A TROPICAL STORM THROUGH 120 HOURS IN BEST AGREEMENT WITH
THE SHIPS AND LGEM MODELS.  HOWEVER...IT IS POSSIBLE THAT THE
CYCLONE COULD WEAKEN MUCH FASTER THAN CURRENTLY FORECAST.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  26/1500Z 17.9N  85.5W   95 KT 110 MPH
 12H  27/0000Z 18.5N  86.2W   95 KT 110 MPH
 24H  27/1200Z 19.5N  87.0W   90 KT 105 MPH
 36H  28/0000Z 20.8N  87.1W   80 KT  90 MPH...INLAND
 48H  28/1200Z 22.0N  87.0W   75 KT  85 MPH...OVER WATER
 72H  29/1200Z 23.0N  85.0W   65 KT  75 MPH
 96H  30/1200Z 23.5N  83.0W   55 KT  65 MPH
120H  31/1200Z 23.5N  82.5W   45 KT  50 MPH
 
$$
FORECASTER BEVEN
 
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