Hurricane IVO

ZCZC MIATCDEP2 ALL
TTAA00 KNHC DDHHMM
HURRICANE IVO DISCUSSION NUMBER  12
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP122007
200 AM PDT FRI SEP 21 2007

THE EYE OF IVO MADE AN APPEARANCE IN INFRARED IMAGERY AROUND 0600
UTC...AND THEN VERY QUICKLY DISAPPEARED.  SINCE THEN...THE OVERALL
SATELLITE APPEARANCE HAS BECOME RAGGED...WITH EVIDENCE OF WESTERLY
VERTICAL WIND SHEAR UNDERCUTTING THE OUTFLOW ON THE WEST SIDE. 
SATELLITE INTENSITY ESTIMATES REMAIN 77 KT FROM TAFB AND SAB...AND
THE INITIAL INTENSITY REMAINS 70 KT.

IVO HAS SLOWED ITS FORWARD SPEED OVER THE PAST FEW HOURS WITH THE
MOTION ESTIMATED AT 340/7.  WATER VAPOR IMAGERY INDICATES A LARGE
UPPER-LEVEL LOW JUST WEST OF THE COAST OF SOUTHERN CALIFORNIA...
WITH WHAT IS BECOMING A NORTH-SOUTH ORIENTED RIDGE EAST OF IVO. 
THE LARGE-SCALE MODELS AGREE THAT THE LOW SHOULD BEGIN MOVING
NORTHEASTWARD IN 24-36 HR.  HOWEVER...THAT IS ABOUT ALL THEY AGREE
ON...AS THEY HAVE A WIDE VARIETY OF SOLUTIONS FOR THE TRACK OF IVO. 
THE ECMWF CONTINUES TO FORECAST IVO TO REACH 20N...THEN MOVE
SOUTHWARD AND DISSIPATE.  THE GFS AND GFDL FORECAST IVO TO MOVE
SLOWLY NORTHWARD AND STALL BEFORE REACHING BAJA CALIFORNIA.  THE
UKMET...HWRF...AND NOGAPS...MOVE IVO NORTHWARD ACROSS BAJA...WITH
THE UKMET CALLING FOR LANDFALL IN LESS THAN 48 HR.  GIVEN THE
UNCERTAINTY...THE NEW FORECAST TRACK IS ESSENTIALLY AN UPDATE OF
THE PREVIOUS TRACK...CALLING FOR THE CENTER OF IVO TO REACH BAJA IN
72-96 HR.  HOPEFULLY SUBSEQUENT MODEL RUNS WILL COME INTO BETTER
AGREEMENT ON THE FORECAST FORWARD SPEED.

WATER VAPOR IMAGERY SUGGESTS THERE IS MORE WESTERLY SHEAR AFFECTING
IVO THAN CURRENTLY ANALYZED BY THE LARGE-SCALE MODELS OR SHIPS
MODEL.  THE IMAGERY ALSO SHOWS DRY AIR WEST OF THE HURRICANE THAT
THE SHEAR MAY ADVECT INTO THE SYSTEM AS IT MOVES NORTHWARD OVER
COOLER WATERS.  THE GFS AND UKMET FORECAST FAVORABLE UPPER-LEVEL
WINDS ALONG THE FORECAST TRACK...WITH THE ECMWF AND NOGAPS SHOWING
A MORE HOSTILE ENVIRONMENT.   THE SHIPS MODEL FORECASTS A SLOW
WEAKENING AFTER 24 HR...WHILE THE HWRF AND THE GFDL SHOW A STRONGER
SYSTEM WITH NO APPRECIABLE WEAKENING UNTIL AFTER 60 HR.  GIVEN THE
CURRENT SHEAR...THE INTENSITY FORECAST WILL GO WITH THE SLOW DECAY
FROM THE SHIPS MODEL AND IS SIMILAR TO THE PREVIOUS FORECAST.
 
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      21/0900Z 19.0N 113.5W    70 KT
 12HR VT     21/1800Z 19.9N 113.5W    70 KT
 24HR VT     22/0600Z 20.8N 113.2W    70 KT
 36HR VT     22/1800Z 21.5N 112.9W    65 KT
 48HR VT     23/0600Z 22.3N 112.5W    60 KT
 72HR VT     24/0600Z 24.0N 112.0W    55 KT
 96HR VT     25/0600Z 25.5N 111.5W    40 KT...INLAND
120HR VT     26/0600Z 27.0N 111.5W    30 KT...OVER WATER
 
$$
FORECASTER BEVEN
 
NNNN