[Tropical] Tropical Cyclone Discussion

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WTNT44 KNHC 100836
TCDAT4
TROPICAL DEPRESSION IRENE DISCUSSION NUMBER  23
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT WED AUG 10 2005

THERE IS LITTLE OR NO EVIDENCE THAT IRENE STILL HAS A CLOSED
CIRCULATION.  AS NOTED IN THE PREVIOUS DISCUSSION...LAST NIGHT'S
QUIKSCAT AMBIGUITIES COULD NOT DEFINE A CENTER...AND THE LOW CLOUD
LINES IN THE NIGHT-VIS IMAGERY ALSO SUGGEST THAT IRENE IS
ELONGATING AND LIKELY HAS DEGENERATED INTO AN OPEN TROUGH. IF THERE
IS A CENTER...IT IS PROBABLY SOUTH OF THE CURRENT ADVISORY POSITION
IN THE DEEP CONVECTION SOUTH OF 22N.  GIVEN THE UNCERTAINTIES
HOWEVER...IT IS PRUDENT TO WAIT FOR VISIBLE IMAGERY BEFORE
DISSIPATING OR RELOCATING THE CYCLONE. THE INITIAL INTENSITY IS
LOWERED TO 25 KT BASED ON THE MOST RECENT QUIKSCAT DATA AND THE
PRESENT LACK OF ORGANIZATION OF THE SYSTEM.  IF IRENE
SURVIVES...THE UPPER-LEVEL FLOW PATTERN IS STILL EXPECTED TO BECOME
GRADUALLY MORE FAVORABLE FOR DEVELOPMENT...AND THE SHIPS GUIDANCE
CONTINUES TO FORECAST STRENGTHENING.  THE OFFICIAL FORECAST...A
BLEND OF THE SHIPS AND GFDL GUIDANCE...CALLS FOR LESS DEVELOPMENT
THAN THE PREVIOUS ADVISORY.

THE INITIAL MOTION OF THIS DISORGANIZED SYSTEM IS HARD TO DETERMINE
BUT MY BEST ESTIMATE IS 270/10.  A MID-LEVEL HIGH IS CENTERED NEAR
BERMUDA TO THE NORTHWEST OF IRENE.  THE GFDL...GFS...UKMET AND
NOGAPS MODELS CONTINUE TO WANT TO TAKE IRENE TO THE WEST-NORTHWEST
AND THEN NORTHWEST LATE IN THE FORECAST PERIOD AS THEY SLIDE THIS
HIGH EASTWARD.  THE SIMPLER BAM MODELS DO NOT HAVE THE NORTHWEST
TURN.  OVER THE PAST FEW DAYS...THE GLOBAL MODELS HAVE HAD A
SIGNIFICANT RIGHT BIAS WHILE THE BAMS HAVE PERFORMED RELATIVELY
WELL.  GIVEN THE PRESENT WESTWARD MOTION AND THESE BIASES...THE
OFFICIAL FORECAST HAS BEEN SHIFTED A LITTLE WESTWARD...AND IS A
COMPROMISE BETWEEN THE FSU SUPERENSEMBLE AND THE MEDIUM BAM.

BOTH THE TRACK AND INTENSITY FORECASTS ARE VERY LOW CONFIDENCE.


FORECASTER FRANKLIN


FORECAST POSITIONS AND MAX WINDS

INITIAL      10/0900Z 22.4N  57.3W    25 KT
 12HR VT     10/1800Z 22.9N  59.0W    25 KT
 24HR VT     11/0600Z 23.7N  61.1W    30 KT
 36HR VT     11/1800Z 24.6N  63.4W    35 KT
 48HR VT     12/0600Z 25.7N  65.5W    40 KT
 72HR VT     13/0600Z 27.0N  68.0W    40 KT
 96HR VT     14/0600Z 28.5N  70.5W    45 KT
120HR VT     15/0600Z 30.0N  73.0W    50 KT


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