Hurricane RITA

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HURRICANE RITA DISCUSSION NUMBER  19
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT THU SEP 22 2005
 
IF RITA HAS NOT PEAKED IN INTENSITY...IT LOOKS LIKE IT IS PRETTY
CLOSE TO DOING SO.  THE LATEST CENTRAL PRESSURE ESTIMATED FROM
RECONNAISSANCE AIRCRAFT DATA IS 897 MB...WHICH SHOWS LITTLE CHANGE
DURING THE PAST 8 HR.  THE MAXIMUM FLIGHT-LEVEL WINDS SO FAR ARE
165 KT IN THE NE EYEWALL...WHICH IS ONLY SLIGHTLY HIGHER THAN THE
161 KT OBSERVED YESTERDAY AFTERNOON.  THE AIRCRAFT DATA SHOWS A
INCREASINGLY STRONG OUTER WIND MAXIMUM THAT IS LIKELY THE START OF
A CONCENTRIC EYEWALL CYCLE...AND SATELLITE IMAGERY SINCE THE END OF
THE ECLIPSE PERIOD SHOWS WARMING OF THE CONVECTION NEAR THE CENTER. 
BASED ON ALL OF THIS...THE INITIAL INTENSITY REMAINS 150 KT.

RITA HAS TURNED A LITTLE TO THE RIGHT DURING THE PAST SEVERAL HOURS
AND THE INITIAL MOTION IS NOW 285/8.  RAWINSONDE DATA SHOWS A
STRONG MID-LEVEL RIDGE CENTERED OVER TEXAS.  LARGE-SCALE MODELS
FORECAST THIS RIDGE TO SHIFT EASTWARD INTO THE SOUTHEASTERN STATES
AND THE EASTERN GULF OF MEXICO DURING THE NEXT 48 HR.  THIS SHOULD
ALLOW RITA TO TURN MORE NORTHWARD WITH TIME.  THE TRACK GUIDANCE IS
NOW CLUSTERED AROUND A LANDFALL BETWEEN THE SABINE RIVER AND
MATAGORDA TEXAS IN 48-60 HR...WITH A NET EASTWARD SHIFT OF THE
GUIDANCE SINCE THE LAST PACKAGE.  THE NEW FORECAST TRACK IS ALSO
SHIFTED EASTWARD ABOUT 30 N MI...CALLING FOR LANDFALL NEAR THE
BOLIVAR PENINSULA AND GALVESTON BAY.  HOWEVER...IT SHOULD BE NOTED
THAT THE NEW TRACK IS ALONG THE LEFT OR WEST SIDE OF THE ENVELOPE OF
GUIDANCE.

THE INTENSITY FORECAST REMAINS SOMEWHAT PROBLEMATIC.  FIRST...THE
MORE NORTHERLY TRACK WILL LIKELY KEEP RITA OVER THE LOOP CURRENT
LONGER THAN PREVIOUSLY EXPECTED...SO THE EFFECT OF LOWER OCEAN HEAT
CONTENT MAY BE SOMEWHAT LESS THAN PREVIOUSLY EXPECTED IN THE FIRST
24 HR OR SO.  SECOND...THE GFS AND SHIP MODELS FORECAST SIGNIFICANT
SHEAR OVER RITA AFTER 24 HR...WHICH RESULTS IN SHIPS CALLING FOR
SIGNIFICANT WEAKENING.  SHEAR ANALYSES FROM CIMSS AT THE UNIVERSITY
OF WISCONSIN SHOW ABOUT 12 KT OF SOUTHERLY SHEAR CAUSED BY AN
UPPER-LEVEL ANTICYCLONE EAST OF RITA...AND THE LARGE-SCALE MODELS
SUGGEST THIS PATTERN WILL CONTINUE UNTIL LANDFALL.  HOWEVER...THE
GFS AND SHIPS MAY BE OVERDOING THE SHEAR.  FINALLY...THERE WILL BE
AT LEAST ONE AND POSSIBLE MORE CONCENTRIC EYEWALL CYCLES BEFORE
LANDFALL.  THE INTENSITY FORECAST IS BASED ON THE PREMISE THAT
SHEAR AND REDUCED OUTFLOW WILL CAUSE A GRADUAL WEAKENING...
ESPECIALLY AFTER RITA MOVES WEST OF THE LOOP CURRENT IN 24-36 HR. 
SUPERIMPOSED ON TOP OF THIS WILL BE FLUCTUATIONS CAUSED BY
CONCENTRIC EYEWALL CYCLES.  THE NEW INTENSITY FORECAST IS AN UPDATE
OF THE PREVIOUS FORECAST...CALLING FOR SLOW OVERALL WEAKENING BUT
NOT AS MUCH AS SHOWN BY SHIPS.
  
FORECASTER BEVEN
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      22/0900Z 24.9N  88.0W   150 KT
 12HR VT     22/1800Z 25.3N  89.3W   150 KT
 24HR VT     23/0600Z 26.1N  91.1W   145 KT
 36HR VT     23/1800Z 27.2N  92.8W   140 KT
 48HR VT     24/0600Z 28.8N  94.3W   130 KT
 72HR VT     25/0600Z 32.0N  95.5W    65 KT...INLAND
 96HR VT     26/0600Z 34.1N  95.0W    30 KT...INLAND
120HR VT     27/0600Z 34.5N  94.5W    25 KT...INLAND DISSIPATING
 
 
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