Hurricane IVO

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HURRICANE IVO DISCUSSION NUMBER  11
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP122007
800 PM PDT THU SEP 20 2007

SATELLITE IMAGES INDICATE THAT A LARGE BURST OF CONVECTION IS NEAR
THE CENTER OF IVO.  EVEN THOUGH AN EYE IS NOT VISIBLE IN
CONVENTIONAL IMAGERY...MICROWAVE DATA SHOW AN EYE WHICH HAS BEEN
OCCASIONALLY OPEN.  THERE HAS BEEN LITTLE CHANGE IN THE SATELLITE
INTENSITY ESTIMATES AND THE INITIAL INTENSITY IS LEFT AT 70 KT. 
ALTHOUGH THE FORECAST SHEAR IS LIGHT AND THE WATER RELATIVELY
WARM...NONE OF THE RELIABLE INTENSITY MODELS SHOW ANY STRENGTHENING
WITH IVO.  PERHAPS THIS IS DUE TO THE HURRICANE MOVING CLOSER TO
THE RELATIVELY STABLE AIR TO THE NORTH.  IN ANY EVENT...THE
INTENSITY FORECAST IS ALMOST THE SAME AS THE PREVIOUS ONE IN THE
SHORT-TERM...BUT A LITTLE LOWER BEYOND 2 DAYS BECAUSE MOST MODELS
SHOW INCREASING SHEAR AND THE SYSTEM WILL LIKELY BE INTERACTING
WITH LAND.

SSMI AND AMSR-E MICROWAVE DATA SHOW THAT IVO IS MOVING FASTER
TONIGHT TOWARD THE NORTH...350/8.  THE TRACK FORECAST IS
PROBLEMATIC TO SAY THE LEAST.  FOR THE NEXT DAY OR SO...THE
HURRICANE WILL BE TRAVELING NORTHWARD IN AN AREA OF WEAK STEERING
CURRENTS BETWEEN A RIDGE OVER CENTRAL MEXICO AND A RATHER DEEP
MIDDLE- TO UPPER-LEVEL LOW OFFSHORE OF SOUTHERN CALIFORNIA.  THE
MODELS ARE IN RATHER POOR AGREEMENT ON WHETHER IVO WILL EVENTUALLY
GET CAUGHT UP IN THE SOUTHWESTERLY FLOW AHEAD OF THE LOW OR GET
LEFT BEHIND IN THE AREA OF LIGHT STEERING CURRENTS.  THE
NOGAPS/UKMET/HWRF MODELS FAVOR THE SYSTEM GETTING CARRIED TO THE
NORTHEAST RATHER QUICKLY AND IMPACTING BAJA CALIFORNIA...WHILE THE
GFS/ECMWF/GFDN/GFDL MODELS DO NOT SHOW ANY LAND IMPACTS.  THE
OFFICIAL TRACK FORECAST IS A LITTLE FASTER IN THE FIRST DAY DUE TO
THE INITIAL MOTION BUT IS CLOSE TO THE CONSENSUS IN THE LONG-TERM.
 
GIVEN THE EXTREME UNCERTAINTY PRESENT IN THE OFFICIAL FORECAST AT
THIS TIME...INTERESTS IN SOUTHERN BAJA CALIFORNIA SHOULD CLOSELY
MONITOR THE PROGRESS OF IVO.
  
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      21/0300Z 18.8N 113.4W    70 KT
 12HR VT     21/1200Z 19.7N 113.5W    70 KT
 24HR VT     22/0000Z 20.6N 113.1W    70 KT
 36HR VT     22/1200Z 21.3N 112.8W    65 KT
 48HR VT     23/0000Z 22.0N 112.5W    60 KT
 72HR VT     24/0000Z 23.5N 112.0W    55 KT
 96HR VT     25/0000Z 25.0N 111.5W    45 KT...INLAND OVER BAJA
120HR VT     26/0000Z 26.5N 111.5W    30 KT...INLAND OVER BAJA
 
$$
FORECASTER BLAKE
 
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