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TROPICAL STORM IVO DISCUSSION NUMBER 13
NATIONAL WEATHER SERVICE MIAMI FL
2 PM PDT THU SEP 13 2001
CONVECTION WITH THIS SYSTEM HAS CONTINUED TO WEAKEN THROUGH THE
DAY...LIKELY THE RESULT OF IVO MOVING INTO COLDER WATERS. ALTHOUGH
THERE MAY BE SOME BRIEF BURSTS OF CONVECTION OVER THE NEXT 12 TO 24
HOURS...THIS SYSTEM IS EXPECTED TO CONTINUE WEAKENING AND DISSIPATE
BEYOND 48 HOURS. DVORAK INTENSITY ESTIMATES OF 3.0/3.0 FROM
TAFB...2.0/2.5 FROM SAB...AND AN EARLIER 2.5/2.5 FROM AIR FORCE
GLOBAL SUPPORT DROPPING THE INITIAL INTENSITY TO 40 KNOTS IN THIS
ADVISORY. ALTHOUGH THE VERTICAL SHEAR IS WEAKER THAN 24 HOURS
EARLIER...IVO HAS MISSED THE OPPORTUNITY TO INTENSIFY. NOW MOVING
INTO COLD WATER...24 DEGREES CELSIUS AND LESS...NO FURTHER
INTENSIFICATION IS FORECAST. ALL AVAILABLE INTENSITY GUIDANCE BEGINS
TO RAPIDLY WEAKEN THE SYSTEM OVER THE NEXT 24 TO 48 HOURS AND THE
OFFICIAL FORECAST IS A REFLECTION OF THIS.
TRACK FORECAST REMAINS THE SAME WITH A WEAK LOW TO MIDDLE LEVEL
RIDGE PROVIDING THE STEERING FOR IVO OVER THE NEXT 48 HOURS. THE
CONSENSUS OF TRACK FORECAST GUIDANCE INDICATES A GENERAL NORTHWEST
TO WEST-NORTHWEST MOTION OVER THE NEXT 48 HOURS. THEREAFTER...THE
AVIATION MODEL TAKES WHAT IS LEFT OF THIS SYSTEM FURTHER WEST...
WHILE NOGAPS TURNS THE SYSTEM NORTH-NORTHWEST. IN EITHER EVENT...THE
CIRCULATION IS NOT EXPECTED TO LAST BEYOND 48 HOURS. THE OFFICIAL
TRACK REMAINS CONSISTENT WITH THE PREVIOUS FORECAST...ALTHOUGH
SLIGHTLY TO THE RIGHT AND IN AGREEMENT WITH THE NOGAPS AND GUNS
TRACK GUIDANCE THROUGH 48 HOURS.
MOISTURE FROM THIS SYSTEM IS SPREADING NORTHWARD INTO THE
SOUTHWESTERN UNITED STATES AND MAY INCREASE THE POTENTIAL FOR
RAINFALL IN THIS AREA.
FORECASTER AVILA/HOLWEG
FORECAST POSITIONS AND MAX WINDS
INITIAL 13/2100Z 24.3N 114.2W 40 KTS
12HR VT 14/0600Z 25.3N 115.6W 35 KTS
24HR VT 14/1800Z 26.7N 117.4W 30 KTS
36HR VT 15/0600Z 27.4N 118.6W 25 KTS
48HR VT 15/1800Z 28.0N 120.0W 20 KTS...DISSIPATING
72HR VT 16/1800Z...DISSIPATED
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