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Hurricane JOHN


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HURRICANE JOHN DISCUSSION NUMBER  16
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP112006
200 AM PDT FRI SEP 01 2006

THE SATELLITE APPEARANCE OF JOHN WHICH HAD DEGRADED EARLIER IN THE
EVENING...HAS BECOME MORE ORGANIZED ONCE AGAIN. AN EYE IS NOW
DISCERNIBLE IN THE INFRARED IMAGERY AND IS VERY WELL DEFINED ON THE
LOS CABOS RADAR. IT IS POSSIBLE THAT JOHN HAS GONE THROUGH ANOTHER
EYEWALL REPLACEMENT CYCLE AND THE EYE HAS BEEN CONTRACTING ON THE
RADAR IMAGES. DVORAK INTENSITY ESTIMATES RANGE FROM 90 KT FROM
AFWA... 102 KT FROM SAB...TO 115 KT FROM TAFB. THE INITIAL
INTENSITY ESTIMATE WILL USE A BLEND OF THESE ESTIMATES AND IS SET
AT 100 KT.  AN UNITED STATES AIR FORCE RESERVE HURRICANE HUNTER
AIRCRAFT IS EXPECTED TO PROVIDE A BETTER ASSESSMENT OF THE
INTENSITY OF JOHN LATER THIS MORNING.
 
JOHN HAS BEEN MOVING A LITTLE LEFT OR WEST OF TRACK DURING THE PAST
6 HOURS.  A LONGER TERM 12-HOUR MOTION IS ESTIMATED AT 310/11 KT
AND THIS IS USED FOR THE ADVISORY. DESPITE THE RECENT MORE WESTWARD
TRENDS THE TRACK GUIDANCE IS IN FAIRLY GOOD AGREEMENT ON A
NORTHWESTWARD MOTION ACROSS OR NEAR THE SOUTHERN BAJA PENINSULA
FOR THE NEXT DAY OR TWO. THEREAFTER...THERE IS A VERY LARGE SPREAD 
IN THE GUIDANCE AND MUCH HIGHER THAN NORMAL LEVEL OF UNCERTAINTY 
IN THE OFFICIAL TRACK FORECAST.  THE GFDL AND GFS SHOW JOHN MOVING
NORTHWARD ALONG THE BAJA PENINSULA.  THE UKMET...NOGAPS...AND FSU
SUPERENSEMBLE CONTINUE TO SHOW A WEST-NORTHWESTWARD BEND AFTER 48
HOURS. THE OFFICIAL TRACK IS ADJUSTED IN THE SHORT-TERM TO ACCOUNT
FOR THE MORE WESTWARD INITIAL MOTION...BUT LATER IN THE PERIOD IS 
ADJUSTED RIGHT OF THE PREVIOUS TRACK CLOSER TO THE CONSENSUS OF 
THE GLOBAL MODELS. 
 
THE GFDL AND SHIPS INTENSITY GUIDANCE BOTH FORECAST SOME ADDITIONAL
STRENGTHENING PRIOR TO JOHN REACHING THE SOUTHERN TIP OF THE BAJA
PENINSULA IN ABOUT 12 HOURS AND THE OFFICIAL FORECAST WILL FOLLOW
SUIT.  THEREAFTER...INTERACTION WITH LAND AND COOLER WATERS WEST OF
THE BAJA PENINSULA SHOULD INITIATE GRADUAL WEAKENING. JOHN WILL
LIKELY WEAKEN AT A FASTER RATE BEYOND 48 HOURS AS IT ENCOUNTERS
SSTS OF 23-24 DEGREES CELSIUS.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      01/0900Z 21.7N 108.8W   100 KT
 12HR VT     01/1800Z 22.8N 110.1W   105 KT
 24HR VT     02/0600Z 23.9N 111.4W   100 KT
 36HR VT     02/1800Z 24.8N 112.7W    90 KT
 48HR VT     03/0600Z 25.4N 114.0W    75 KT
 72HR VT     04/0600Z 26.3N 116.5W    60 KT
 96HR VT     05/0600Z 26.8N 119.0W    45 KT
120HR VT     06/0600Z 27.0N 122.0W    35 KT
 
$$
FORECASTER BROWN/KNABB
 
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