Hurricane JOHN

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HURRICANE JOHN DISCUSSION NUMBER  10
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP112006
200 PM PDT WED AUG 30 2006
 
JOHN REMAINS A DANGEROUS CATEGORY FOUR HURRICANE THIS AFTERNOON.
VISIBLE IMAGERY SUGGESTS THAT JOHN IS UNDERGOING A CONCENTRIC
EYEWALL REPLACEMENT CYCLE...AND THIS WAS ALSO EVIDENT ON A 1520 UTC
SSMI MICROWAVE PASS.  BOTH THE OCCURRENCE AND TIME SCALE OF THESE
EYEWALL REPLACEMENT CYCLES ARE ALMOST IMPOSSIBLE TO PREDICT.  IN
ANY EVENT...CONSIDERING THE CURRENT INNER-CORE STRUCTURE OF THE
HURRICANE...NO CHANGE IN INTENSITY IS INDICATED FOR THE EARLY PART
OF THE FORECAST PERIOD.  SOME INCREASE IN STRENGTH IS POSSIBLE ONCE
THE EYEWALL REPLACEMENT HAS ENDED.  THE HURRICANE WILL REMAIN IN A
LOW SHEAR AND WARM WATER ENVIRONMENT FOR THE NEXT 72 HOURS.  THE
ONLY INHIBITING FACTOR WOULD APPEAR TO BE THE INTERACTION WITH
LAND. 

THE INITIAL MOTION IS 310/12...A LITTLE FASTER THAN IN THE PREVIOUS
ADVISORY.  THE FORECAST TRACK IS ESSENTIALLY AN UPDATE OF THE
PREVIOUS FORECAST...AND THE REASONING IS BASICALLY THE SAME. 
JOHN SHOULD CONTINUE TO MOVE TOWARD THE NORTHWEST AND AROUND THE
SOUTHWESTERN PERIPHERY OF A MIDDLE- TO UPPER-LEVEL RIDGE OVER
NORTHERN MEXICO...PARALLEL TO BUT VERY CLOSE TO THE SOUTHWEST COAST
OF MEXICO. ONLY A SLIGHT WOBBLE TO THE RIGHT COULD BRING THE CENTER
ASHORE IN THE HURRICANE WARNING AREA. 

THE GOVERNMENT OF MEXICO HAS ISSUED A HURRICANE WATCH OVER PORTIONS
OF THE SOUTHERN BAJA PENINSULA...AND EXTENDED THE TROPICAL STORM
WATCH OVER MAINLAND MEXICO.  

THE UNITED STATES AIR FORCE RECONNAISSANCE AIRCRAFT WILL BE
INVESTIGATING THE HURRICANE TOMORROW AT 1800 UTC. 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      30/2100Z 17.4N 103.3W   115 KT
 12HR VT     31/0600Z 18.6N 104.7W   115 KT
 24HR VT     31/1800Z 20.4N 106.5W   125 KT
 36HR VT     01/0600Z 21.8N 107.9W   125 KT
 48HR VT     01/1800Z 22.8N 109.5W   120 KT
 72HR VT     02/1800Z 24.0N 112.5W   105 KT
 96HR VT     03/1800Z 24.5N 115.5W    90 KT
120HR VT     04/1800Z 24.5N 119.0W    70 KT
 
$$
FORECASTER MAINELLI/PASCH
 
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