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Hurricane IVAN


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TROPICAL STORM IVAN DISCUSSION NUMBER  71
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 PM EDT THU SEP 23 2004
 
AFTER THE EARLIER A BURST OF CONVECTION...THUNDERSTORM ACTIVITY HAS
DWINDLED AND THE WIND HAVE DECREASED ACCORDINGLY. THE INITIAL
INTENSITY OF 40 KT AND A PRESSURE OF 1003 MB IS BASED ON THE LAST
RECON REPORT AROUND 17Z.
 
THE INITIAL MOTION ESTIMATE IS 310/07. THERE IS NO SIGNIFICANT
CHANGE TO THE PREVIOUS FORECAST REASONING. IVAN SHOULD CONTINUE TO
MOVE NORTHWESTWARD TO WEST-NORTHWESTWARD AND BE INLAND WITHIN THE
NEXT 12 HOURS OVER SOUTHWESTERN LOUISIANA OR THE UPPER-TEXAS COAST.
AFTERWARDS...RAPID WEAKENING WILL RESULT IN THE LOW-LEVEL
CIRCULATION DECOUPLING FROM THE MID- AND UPPER-LEVEL CIRCULATIONS.
THIS SHOULD ALLOW THE LOW-LEVEL CIRCULATION TO BE STEERED SLOWLY
WEST AND THEN SOUTHWESTWARD BY A LARGE LOW-LEVEL RIDGE/HIGH THAT IS
FORECAST TO BUILD EASTWARD OVER THE CENTRAL AND SOUTHERN PLAINS
BEHIND A COLD FRONT. THE TRACK SCENARIO REMAINS CONSISTENT WITH THE
SHALLOW BAM MODEL AND MOST OF THE GLOBAL MODELS. WHILE A FEW MODELS
TAKE THE LOW-LEVEL CIRCULATION BACK OVER THE GULF OF MEXICO IN
36-48 HOURS...STRONG SOUTHWESTERLY UPPER-LEVEL WINDS OF MORE THAN
40 KT SHOULD PREVENT ANY REDEVELOPMENT FROM OCCURRING.
 
WHILE IVAN IS NOT EXPECTED TO BE A PROLIFIC WIND PRODUCER...ITS SLOW
FORWARD SPEED FOR THE NEXT SEVERAL DAYS MAY BRING UP LARGE AMOUNTS
OF GULF MOISTURE THAT COULD RESULT IN LOCALLY HEAVY RAINFALL.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      23/2100Z 29.4N  93.0W    40 KT
 12HR VT     24/0600Z 30.0N  94.1W    35 KT...INLAND
 24HR VT     24/1800Z 30.4N  95.0W    30 KT...INLAND
 36HR VT     25/0600Z 30.2N  95.7W    25 KT...INLAND
 48HR VT     25/1800Z 29.6N  96.4W    20 KT...DISSIPATING INLAND
 72HR VT     26/1800Z 28.8N  97.2W    20 KT...REMNANT LOW INLAND
 96HR VT     27/1800Z...DISSIPATED INLAND
 
 
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