[Tropical] Tropical Cyclone Discussion

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WTNT42 KNHC 260906
TCDAT2
HURRICANE KATRINA DISCUSSION NUMBER  11
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT FRI AUG 26 2005

DUE TO THE SOUTHWESTWARD PATH TAKEN BY KATRINA OVER EXTREME SOUTHERN
FLORIDA...ITS CENTER SPENT ONLY ABOUT SEVEN HOURS OVER LAND...AND
MUCH OF THAT TIME OVER THE RELATIVELY MOIST EVERGLADES. AS A RESULT
OF THIS AND THE FAVORABLE ATMOSPHERIC ENVIRONMENT... KATRINA DID
NOT WEAKEN ALL THAT MUCH OVERNIGHT. THE CENTER CROSSED THE COAST OF
SOUTHWESTERN FLORIDA AT ABOUT 0530Z... EMERGING OVER THE WARM
WATERS OF THE GULF OF MEXICO. WSR-88D RADAR IMAGERY FROM MIAMI AND
KEY WEST STILL DEPICT AN IMPRESSIVE CYCLONE... WITH STRONG
CONVECTION CONTINUING JUST SOUTHEAST OF THE CENTER... WHICH STILL
QUALIFIES AS SOMEWHAT OF AN EYEWALL. A SECONDARY BUT STRONG CURVED
BAND ALSO EXTENDS FROM JUST EAST OF THE CENTER SOUTHWESTWARD ALONG
THE ENTIRE CHAIN OF THE FLORIDA KEYS... AND A LARGER OUTER BAND
EXTENDS ALL THE WAY AROUND THE SOUTHERN PORTIONS OF THE CIRCULATION
BETWEEN THE KEYS AND CUBA TO WEST OF DRY TORTUGAS. WHILE THE LATEST
DOPPLER RADAR VELOCITIES ONLY SUPPORT 60 KT AT THE SURFACE... THESE
VALUES ARE STEADILY CLIMBING... AND THE FIRST DVORAK ESTIMATES OVER
THE GULF ARE A UNANIMOUS T4.0/65 KT. THEREFORE... KATRINA IS
REASSIGNED HURRICANE STATUS WITH INTENSITY OF 65 KT.

RADAR IMAGERY INDICATES THAT KATRINA HAS STARTED TO MOVE NEARLY DUE
WESTWARD... AND THE INITIAL MOTION ESTIMATE IS 260/4. THIS MOTION
IS EXPECTED TO CONTINUE FOR THE NEXT SEVERAL HOURS TO THE SOUTH OF
AN EASTWARD EXTENSION OF THE MID-LEVEL RIDGE CENTERED OVER TEXAS.
THE DYNAMICAL MODELS GENERALLY AGREE THAT THIS RIDGE WILL WEAKEN
AND MIGRATE WESTWARD... ALLOWING KATRINA TO GRADUALLY TURN
NORTHWARD INTO A WEAKNESS IN THE RIDGING. THE NEW SUITE OF GUIDANCE
HAS SHIFTED A LITTLE TO THE WEST... AS HAS THE OFFICIAL FORECAST...
WHICH IS A BLEND OF THE PREVIOUS ADVISORY AND THE LATEST MODEL
CONSENSUS.

ALL INDICATIONS ARE THAT KATRINA WILL BE A DANGEROUS HURRICANE IN
THE NORTHEASTERN GULF OF MEXICO WITHIN THE NEXT COUPLE OF DAYS.
THIS SEEMS EVEN MORE LIKELY NOW GIVEN ITS CURRENT STRENGTH EMERGING
AGAIN OVER WATER.  AS KATRINA MOVES FARTHER NORTH IN THE EASTERN
GULF OF MEXICO... ATMOSPHERIC CONDITIONS SHOULD ONLY BECOME MORE
CONDUCIVE FOR STRENGTHENING AS A LARGE UPPER LEVEL ANTICYCLONE
DOMINATES OVER THE GULF OF MEXICO.  THE OFFICIAL FORECAST IS CLOSE
TO THE SHIPS GUIDANCE IN BRINGING KATRINA TO 90 KT BY 72 HOURS....
BUT THIS COULD BE CONSERVATIVE SINCE THE GFDL AND GFDN FORECAST A
MAJOR HURRICANE.  IT IS CERTAINLY POSSIBLE THAT KATRINA COULD
ATTAIN MAJOR HURRICANE STATUS BEFORE MAKING LANDFALL SOMEWHERE ON
THE NORTHERN GULF COAST.

FORECASTER KNABB


FORECAST POSITIONS AND MAX WINDS

INITIAL      26/0900Z 25.3N  81.5W    65 KT
 12HR VT     26/1800Z 25.2N  82.6W    70 KT
 24HR VT     27/0600Z 25.4N  83.8W    75 KT
 36HR VT     27/1800Z 25.9N  84.6W    80 KT
 48HR VT     28/0600Z 26.6N  85.4W    85 KT
 72HR VT     29/0600Z 28.5N  86.5W    90 KT
 96HR VT     30/0600Z 33.0N  84.5W    40 KT...INLAND
120HR VT     31/0600Z 39.0N  79.0W    25 KT...INLAND


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