Tropical Storm IVO

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TROPICAL STORM IVO DISCUSSION NUMBER  14
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP122007
200 PM PDT FRI SEP 21 2007
 
IVO APPEARED TO BE IN A CONVECTIVE LULL ABOUT 5 OR 6 HOURS AGO...
BUT A BURST OF DEEP CONVECTION HAS REDEVELOPED NORTHEAST OF THE
LOW-LEVEL CIRCULATION CENTER DURING THE LAST COUPLE OF HOURS.
DESPITE THE NEW CONVECTION AND A WELL-DEFINED CIRCULATION...DVORAK
DATA T-NUMBERS AND CURRENT INTENSITY ESTIMATES FROM BOTH TAFB AND
SAB ARE 55 KT AND 65 KT RESPECTIVELY.  A 1356 UTC QUIKSCAT PASS
ESTIMATED 50 TO 55 KT WIND VECTORS.  BLENDING THE ABOVE ESTIMATES
RESULTS IN LOWERING THE INITIAL INTENSITY TO 60 KT.  WHILE THE
WATERS ARE EXPECTED TO REMAIN SUFFICIENTLY WARM ALONG THE FORECAST
TRACK...WESTERLY TO SOUTHWESTERLY SHEAR IS FORECAST TO GRADUALLY
INCREASE.  THE OFFICIAL INTENSITY FORECAST CALLS FOR SLOW WEAKENING
AFTER 12 HOURS...WHICH FOLLOWS CLOSELY WITH THE INTENSITY MODEL
CONSENSUS OF THE GFDL...SHIPS...AND HWRF.
 
IVO IS MOVING SLOWLY TO THE NORTH AND THE MOTION IS ESTIMATED AT
005/5.  THE GENERAL TRACK PHILOSOPHY IS COMPLICATED AND SOLUTIONS
FROM THE VARIOUS MODELS ARE HIGHLY DIVERGENT.  THE MID- TO UPPER-
LEVEL LOW REMAINS CENTERED JUST WEST OF THE SOUTHERN CALIFORNIA
COAST.  AS THE LOW LIFTS NORTHEASTWARD IN ABOUT 36 HOURS OR SO...IT
IS DIFFICULT TO DETERMINE HOW MUCH INFLUENCE THE LINGERING TROUGH
BEHIND THE LOW WILL HAVE ON STEERING IVO NORTHEASTWARD.  ONLY THE
UKMET AND NOGAPS MODELS ACCELERATE THE CYCLONE NORTHEASTWARD INTO
MAINLAND MEXICO.  THE ECMWF...GFS...HWRF...AND GFDL MODELS STALL
IVO SOUTH OF THE BAJA PENINSULA COAST IN ABOUT 3 DAYS.  THE
OFFICIAL TRACK FORECAST STILL CALLS FOR IVO TO MOVE ACROSS THE
SOUTHERN BAJA PENINSULA... BUT AT A SLOWER PACE AND SLIGHTLY TO
THE EAST OF THE PREVIOUS FORECAST...WHICH IS CLOSEST TO THE FSSE
GUIDANCE.
 
ONCE AGAIN...GIVEN THE UNCERTAINTY PRESENT IN THE OFFICIAL
FORECAST...INTERESTS IN SOUTHERN BAJA CALIFORNIA SHOULD CLOSELY
MONITOR THE PROGRESS OF IVO.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      21/2100Z 20.1N 113.4W    60 KT
 12HR VT     22/0600Z 20.8N 113.2W    60 KT
 24HR VT     22/1800Z 21.6N 112.9W    55 KT
 36HR VT     23/0600Z 22.3N 112.6W    50 KT
 48HR VT     23/1800Z 23.0N 112.2W    45 KT
 72HR VT     24/1800Z 24.0N 111.5W    40 KT
 96HR VT     25/1800Z 25.0N 111.0W    30 KT...INLAND
120HR VT     26/1800Z 26.0N 110.5W    25 KT
 
$$
FORECASTER MAINELLI
 
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