Hurricane JOHN

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HURRICANE JOHN DISCUSSION NUMBER  14
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP112006
200 PM PDT THU AUG 31 2006

REPORTS FROM THE AIR FORCE RECONNAISSANCE AIRCRAFT THIS AFTERNOON
INDICATE THAT JOHN IS WEAKER THAN EARLIER INTENSITY ESTIMATES. A
DROPSONDE IN THE EYE MEASURED A CENTRAL PRESSURE OF 973 MB WITH A
20 KT SURFACE WIND...SO THE ACTUAL MINIMUM PRESSURE IS ACTUALLY A
LITTLE LOWER.  CURRENT INTENSITY IS SET AT 90 KT...IN REASONABLE
AGREEMENT WITH A SURFACE WIND MEASUREMENT FROM A GPS DROPSONDE IN
THE EASTERN EYEWALL.  ASIDE FROM THE EYEWALL REPLACEMENT OBSERVED
YESTERDAY...IT IS NOT CLEAR WHY JOHN HAS WEAKENED SO MUCH. PERHAPS
IT WAS DUE TO THE INTERACTION OF THE CIRCULATION WITH THE
MOUNTAINOUS LANDMASS OF SOUTHWESTERN MEXICO.  ALTHOUGH JOHN HAS
WEAKENED...IT STILL HAS A WELL-ESTABLISHED UPPER-LEVEL OUTFLOW
PATTERN AND THERE IS AN OPPORTUNITY FOR SOME RESTRENGTHENING BEFORE
THE CENTER REACHES SOUTHERN BAJA CALIFORNIA.  ONCE JOHN STARTS
MOVING AWAY FROM THE BAJA PENINSULA...IT SHOULD BEGIN TRAVERSING
SIGNIFICANTLY COOLER SEA SURFACE TEMPERATURES AND STEADILY WEAKEN. 

THE INITIAL MOTION IS 315/11...SLIGHTLY TO THE RIGHT OF THE PREVIOUS
ESTIMATE.   JOHN CONTINUES TO MOVE ALONG THE SOUTHWESTERN PERIPHERY
OF A MIDDLE- TO UPPER-LEVEL RIDGE...WITH SOME POSSIBLE INTERACTION
WITH THE SMALLER HURRICANE...KRISTY...LOCATED SOME 600 MILES TO ITS
WEST.  NOW THAT THE GFDL MODEL HAS SHIFTED FURTHER TO THE LEFT...
THE TRACK MODEL GUIDANCE IS NOW IN BETTER AGREEMENT ON A TRACK THAT
WOULD TAKE JOHN NEAR OR OVER THE SOUTHERN BAJA PENINSULA...AND THEN
TAKES JOHN ON A MORE WESTWARD TRACK THEREAFTER.

THE HURRICANE WARNING HAS BEEN EXTENDED A LITTLE NORTHWARD ALONG
BOTH COASTS OF THE BAJA PENINSULA.  THE WIND RADII HAVE BEEN
ADJUSTED FROM THE OBSERVATIONS REPORTED BY THE RECONNAISSANCE
AIRCRAFT. 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      31/2100Z 20.7N 107.0W    90 KT
 12HR VT     01/0600Z 21.8N 108.0W    95 KT
 24HR VT     01/1800Z 22.8N 109.4W    95 KT
 36HR VT     02/0600Z 23.5N 110.7W    90 KT
 48HR VT     02/1800Z 24.1N 112.2W    85 KT
 72HR VT     03/1800Z 24.7N 115.0W    65 KT
 96HR VT     04/1800Z 25.0N 119.0W    55 KT
120HR VT     05/1800Z 25.0N 123.0W    40 KT
 
$$
FORECASTER MAINELLI/PASCH
 
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