[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT44 KNHC 230835
TCDAT4
TROPICAL STORM IVAN DISCUSSION NUMBER  69
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT THU SEP 23 2004

IVAN REMAINS A POORLY-ORGANIZED TROPICAL STORM...WITH MOST OF THE
DEEP CONVECTION BEING SHEARED TO THE NORTHEAST OF THE LOW-LEVEL
CENTER.  THERE IS STILL A POSSIBILITY OF THE SHEAR RELAXING...AND
SOME INTENSIFICATION...BEFORE THE CENTER CROSSES THE COAST.
HOWEVER...THE WINDOW OF OPPORTUNITY FOR THIS TO HAPPEN IS CLOSING.

LATEST CENTER FIXES INDICATE AN INCREASE IN FORWARD SPEED AND THE
INITIAL MOTION ESTIMATE IS 300/13. IVAN IS BEING STEERED MAINLY BY
A LOW- TO MID-LEVEL RIDGE TO ITS NORTH...WHICH THE GFS MODEL
PREDICTS TO WEAKEN WITHIN THE NEXT 24 HOURS. THUS SOME SLOWING OF
THE FORWARD SPEED IS ANTICIPATED. THE GLOBAL MODELS SHOW A SHARP
LEFTWARD TURN IN 24 TO 48 HOURS IN RESPONSE TO A MID- TO
UPPER-LEVEL TROUGH OVER THE SOUTHWESTERN GULF.  THE OFFICIAL
FORECAST ASSUMES THAT IVAN WILL NOT BE A DEEP ENOUGH CYCLONE TO
RESPOND SIGNIFICANTLY TO THIS TROUGH. THE CURRENT OFFICIAL TRACK IS
A LITTLE TO THE LEFT OF THE PREVIOUS ONE...AND IN BETWEEN THE
MEDIUM AND SHALLOW LAYER BAM TRACKS.

FORECASTER PASCH

FORECAST POSITIONS AND MAX WINDS

INITIAL      23/0900Z 28.2N  91.6W    35 KT
 12HR VT     23/1800Z 29.2N  93.4W    40 KT
 24HR VT     24/0600Z 30.1N  95.0W    35 KT...INLAND
 36HR VT     24/1800Z 30.7N  96.1W    30 KT...INLAND
 48HR VT     25/0600Z 31.0N  97.0W    20 KT...INLAND...DISSIPATING
 72HR VT     26/0600Z 31.1N  98.0W    20 KT...INLAND...REMNANT LOW
 96HR VT     27/0600Z...DISSIPATED


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