[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT42 KNHC 250243
TCDAT2
TROPICAL STORM KATRINA DISCUSSION NUMBER   6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT WED AUG 24 2005

THE 2300Z RECONNAISSANCE FIX AND RADAR DATA FROM MIAMI AND THE
BAHAMAS INDICATE THAT KATRINA HAS TURNED TOWARD THE WEST DURING THE
LAST COUPLE OF HOURS. IT APPEARS THAT THE CYCLONE IS ALREADY SOUTH
OF THE RIDGE AND EMBEDDED WITHIN WEAK STEERING CURRENTS. THIS
PATTERN WOULD FORCE KATRINA TO MOVE VERY SLOWLY ON A GENERAL
WESTWARD TRACK FOR THE NEXT 24 TO 48 HOURS. THIS MEANS THAT THE
CYCLONE WILL LIKELY BE CROSSING THE SOUTHERN FLORIDA PENINSULA
THURSDAY NIGHT AND ALL DAY FRIDAY. THIS IS CONSISTENT WITH THE
RELIABLE DYNAMICAL GUIDANCE WHICH FOR THE FIRST TWO DAYS...BRINGS
THE CYCLONE SLOWLY WESTWARD. BEYOND THREE DAYS...WHEN KATRINA IS
FORECAST TO BE IN THE EASTERN GULF OF MEXICO...THE MODELS  DIVERGE
SIGNIFICANTLY...SUGGESTING TRACKS WHICH COVER THE COAST FROM
MISSISSIPPI EASTWARD. THE OFFICIAL FORECAST TURNS KATRINA NORTHWARD
OVER THE EASTERN GULF OF MEXICO AHEAD OF A STRONG APPROACHING
TROUGH...ON A TRACK WHICH IS VERY CLOSE TO THE GLOBAL MODEL
CONSENSUS.  THIS FORECAST IS RATHER DIFFICULT SINCE ONE OF THE MORE
RELIABLE MODELS...THE GFS...SHOWS THAT THE CYCLONE BARELY TOUCHES
THE EAST COAST OF FLORIDA BEFORE MOVING NORTHWARD....WHILE THE
OUTSTANDING GFDL MOVES KATRINA SOUTH OF DUE WEST ACROSS EXTREME
SOUTH FLORIDA AND THE KEYS AS A VERY INTENSE HURRICANE. THE GFDL
SCENARIO WOULD BE VERY DANGEROUS FOR SOUTH FLORIDA. THIS APPEARS TO
BE UNREALISTIC AT THIS TIME BUT BECAUSE OF THE GOOD PAST
PERFORMANCE OF THIS MODEL...WE MUST PAY CLOSE ATTENTION TO FUTURE
MODEL RUNS.

THE INITIAL INTENSITY HAS BEEN INCREASED TO 45 KNOTS BASED ON DVORAK
ESTIMATES FROM ALL AGENCIES AND A BETTER RADAR PRESENTATION. LATEST
RECONNAISSANCE DATA AT 2300 UTC DID NOT SHOW INTENSIFICATION AND
THE PRESSURE WAS NOT DROPPING. HOWEVER...THE OFFICIAL INTENSITY
FORECAST CALLS FOR A GRADUAL STRENGTHENING...AND MAKES KATRINA A
CATEGORY ONE HURRICANE BEFORE LANDFALL...SINCE THERE IS LOW SHEAR
AND HIGH SEA SURFACE TEMPERATURES ALONG KATRINA'S PATH. THE
INTENSITY FORECAST FOLLOWS THE SHIPS MODEL BUT KATRINA COULD
INTENSIFY A LITTLE MORE THAN ANTICIPATED.

BECAUSE IT IS FORECAST THAT KATRINA BECOMES A HURRICANE BEFORE
LANDFALL...A HURRICANE WARNING HAS BEEN ISSUED FOR A PORTION OF THE
EAST FLORIDA COAST.

FORECASTER AVILA


FORECAST POSITIONS AND MAX WINDS

INITIAL      25/0300Z 26.0N  78.0W    45 KT
 12HR VT     25/1200Z 26.0N  78.8W    55 KT
 24HR VT     26/0000Z 26.0N  79.5W    65 KT
 36HR VT     26/1200Z 26.0N  80.5W    50 KT...INLAND
 48HR VT     27/0000Z 26.3N  81.5W    40 KT...INLAND
 72HR VT     28/0000Z 27.0N  83.0W    50 KT...OVER WATER
 96HR VT     29/0000Z 29.0N  85.0W    70 KT
120HR VT     30/0000Z 32.0N  84.0W    30 KT...INLAND


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