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Tropical Storm RITA (Text)

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TROPICAL STORM RITA DISCUSSION NUMBER   4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 PM EDT SUN SEP 18 2005
 
THE AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT DID NOT FIND A VERY
IMPRESSIVE WIND FIELD JUST ABOVE THE SURFACE NEAR THE CENTER OF
CIRCULATION... BUT DID RECENTLY MEASURE A CENTRAL PRESSURE OF 1005
MB AND MAXIMUM FLIGHT LEVEL WINDS OF 45 KT... WELL TO THE NORTHEAST
OF THE CENTER.  ADDITIONALLY... SHIP OBSERVATIONS FROM WELL TO
THE NORTH AND EAST OF THE CENTER HAVE INDICATED WINDS OF 30-35 KT
DURING THE PAST SEVERAL HOURS.  THESE DATA... COMBINED WITH DVORAK
INTENSITY ESTIMATES OF 30-35 KT SUPPORT UPGRADING THE SYSTEM TO A
TROPICAL STORM WITH 35 KT WINDS.  THE LACK OF WIND NEAR THE CENTER
IS NOT SURPRISING GIVEN THAT ALL OF THE CONVECTION AND PERHAPS A
MID LEVEL CIRCULATION CENTER ARE DISPLACED TO THE NORTH... DUE TO
SOUTHERLY SHEAR CAUSED BY THE UPPER-LEVEL LOW OVER EASTERN CUBA.
 
THE TROPICAL STORM IS STILL IN THE PROCESS OF ORGANIZING.  IT HAS A
FAIRLY LARGE CIRCULATION AND SOME DEEP CONVECTION WITH
TOPS COLDER THAN -70C... AND WHILE UPPER-LEVEL OUTFLOW IS
RESTRICTED TO THE SOUTHWEST DUE TO THE SHEAR... IT IS BECOMING WELL
ESTABLISHED IN THE REMAINING THREE QUADRANTS.  SINCE DYNAMICAL
MODELS FORECAST THE UPPER LOW TO WEAKEN AND ALLOW AN UPPER RIDGE TO
BUILD IN ITS PLACE OVER FLORIDA AND THE NORTHERN
BAHAMAS...ATMOSPHERIC CONDITIONS ARE EXPECTED TO GRADUALLY BECOME
MORE CONDUCIVE FOR STRENGTHENING.  WHILE THE GFDL STILL DOES NOT
FORECAST DEVELOPMENT UNTIL RITA REACHES THE GULF OF MEXICO... THE
SHIPS GUIDANCE FORECAST OF 64 KT BY 48 HOURS SEEMS MORE LIKELY. 
THE NEW OFFICIAL INTENSITY FORECAST IS BASICALLY AN UPDATE OF THE
PREVIOUS ADVISORY...ANTICIPATING A HURRICANE IN 36-48 HOURS. 
ADDITIONAL DEVELOPMENT IS FORECAST ONCE THE STORM REACHES THE GULF
OF MEXICO.

THE INITIAL AND FORECAST MOTION ARE COMPLICATED BY THE ASYMMETRIC
CLOUD PATTERN...WHICH SEEM TO WANT TO DRAG THE SYSTEM NORTH OF A
DUE WEST TRACK...WHILE A MID LEVEL RIDGE TO THE NORTH OF THE
CYCLONE IS TRYING TO FORCE THE SYSTEM DUE WESTWARD.  THESE FACTORS
WILL CONTINUE TO BATTLE FOR THE NEXT DAY OR SO UNTIL THE SHEAR
RELAXES.  THE DYNAMICAL MODELS HAVE SHIFTED FARTHER SOUTH IN TAKING
THE SYSTEM THROUGH THE FLORIDA STRAITS...IN SOME CASES SOUTH OF DUE
WEST...TOWARD THE GULF OF MEXICO.  THE OFFICIAL FORECAST IS ONLY
ADJUSTED SLIGHTLY SOUTHWARD SINCE IT IS QUITE POSSIBLE THE CENTER
WILL REFORM FARTHER NORTH DURING THE NEXT 36 HOURS.
 
 
FORECASTER KNABB
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      18/2100Z 22.2N  72.7W    35 KT
 12HR VT     19/0600Z 22.6N  74.7W    45 KT
 24HR VT     19/1800Z 23.2N  77.3W    50 KT
 36HR VT     20/0600Z 23.5N  79.7W    60 KT
 48HR VT     20/1800Z 23.5N  82.5W    70 KT
 72HR VT     21/1800Z 23.5N  87.5W    75 KT
 96HR VT     22/1800Z 24.0N  91.5W    85 KT
120HR VT     23/1800Z 25.5N  95.0W    95 KT
 
 
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