Hurricane JOHN

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HURRICANE JOHN DISCUSSION NUMBER  20
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP112006
200 AM PDT SAT SEP 02 2006
 
MEXICAN RADAR DATA FROM GUASAVE INDICATES THAT THE CENTER OF JOHN
REMAINS JUST INLAND ALONG THE EAST COAST OF THE SOUTHERN BAJA
CALIFORNIA PENINSULA.  THE EYE HAS ERODED IN BOTH SATELLITE AND
RADAR IMAGERY...BUT THE NORTHERN EYEWALL APPEARS TO BE INTACT ALONG
THE COAST EAST OF LA PAZ.  DUE TO A LACK OF SURFACE OBSERVATIONS
AND INTERACTION WITH MOUNTAINOUS TERRAIN...THE INITIAL INTENSITY IS
RATHER UNCERTAIN.  SINCE THE CENTER IS NOT FAR INLAND THE INTENSITY
WILL BE DECREASED ONLY SLIGHTLY TO 85 KT.
 
THE INITIAL MOTION ESTIMATE IS 330/8. JOHN IS BEING STEERED
NORTH-NORTHWESTWARD AROUND THE WESTERN SIDE OF A MID- TO
UPPER-LEVEL RIDGE OVER MAINLAND MEXICO. THE LATEST GLOBAL MODEL
RUNS CONTINUE TO HAVE A FAIRLY LARGE SPREAD. THE GFDL AND GFS MADE
A RATHER LARGE WESTWARD SHIFT AND NOW INDICATE THAT JOHN COULD
EMERGE OFF THE WEST COAST OF THE BAJA PENINSULA IN ABOUT 24 HOURS.
THE UKMET ALSO SHIFTED WESTWARD BUT KEEPS JOHN ALONG THE EAST COAST
OF THE PENINSULA. DESPITE THE LARGE CHANGES IN THE MODELS...THE
OFFICIAL FORECAST WAS ONLY ADJUSTED SLIGHTLY AND IS JUST RIGHT OR
EAST OF THE MODEL CONSENSUS. THE OFFICIAL TRACK REMAINS ALONG THE
IMMEDIATE EAST COAST OF THE PENINSULA FOR THE NEXT 12-18
HOURS...BEFORE MOVING ACROSS THE CENTRAL PORTION OF THE
PENINSULA...MUCH LIKE THE PREVIOUS ADVISORY.
 
THE INTENSITY FORECAST KEEPS JOHN A HURRICANE FOR ANOTHER 12-18
HOURS...SINCE THE CENTER IS EXPECTED TO REMAIN VERY CLOSE TO THE
COAST OR EVEN BRIEFLY OVER THE BAY OF LA PAZ TODAY. THEREAFTER...
THE OFFICIAL FORECAST WEAKENS JOHN A LITTLE FASTER THAN THE
PREVIOUS ADVISORY DUE TO INTERACTION WITH THE TERRAIN.  THE
INTENSITY FORECAST IS HIGHLY DEPENDENT ON THE FUTURE TRACK OF JOHN.
IF THE HURRICANE REMAINS EAST OF THE OFFICIAL FORECAST ALONG THE
EAST COAST OF THE BAJA PENINSULA...IT COULD BE STRONGER THAN
INDICATED.  HOWEVER...SINCE JOHN IS A SMALL TROPICAL CYCLONE IT
COULD ALSO WEAKEN FASTER OR EVEN DISSIPATE OVER THE MOUNTAINOUS
TERRAIN OF THE BAJA PENINSULA IN THE NEXT COUPLE DAYS.
 
IT APPEARS PROBABLE THAT SOME MOISTURE FROM THE CYCLONE WILL SPREAD
INTO THE SOUTHWESTERN UNITED STATES EVEN THOUGH THE LOW-LEVEL
CENTER OF THE CYCLONE WILL LIKELY NOT APPROACH THAT REGION.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      02/0900Z 24.2N 110.2W    85 KT
 12HR VT     02/1800Z 25.0N 110.8W    75 KT...NEAR COAST
 24HR VT     03/0600Z 26.1N 111.8W    55 KT...INLAND
 36HR VT     03/1800Z 27.2N 112.8W    35 KT...INLAND
 48HR VT     04/0600Z 28.2N 114.0W    25 KT...INLAND
 72HR VT     05/0600Z 29.7N 116.3W    20 KT...REMNANT LOW
 96HR VT     06/0600Z 30.5N 118.0W    20 KT...REMNANT LOW
120HR VT     07/0600Z...DISSIPATED
 
$$
FORECASTER BROWN/KNABB
 
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