Hurricane JOHN

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HURRICANE JOHN DISCUSSION NUMBER   6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP112006
200 PM PDT TUE AUG 29 2006
 
JOHN HAS UNDERGONE RAPID INTENSIFICATION TODAY AND A PINHOLE EYE IS
NOW EVIDENT ON SATELLITE IMAGERY.  24 HOURS AGO THE CYCLONE WAS A
40 KT TROPICAL STORM AND THE INITIAL INTENSITY FOR THIS ADVISORY IS
SET AT 100 KT.  IT SHOULD BE NOTED THAT BOTH TAFB AND SAB DVORAK
CLASSIFICATIONS WERE LIMITED TO DATA T-NUMBERS OF 5.0 OR 90 KT DUE
TO RESTRICTIONS IN THE TECHNIQUE...BUT RAW DATA T-NUMBERS GIVE
ESTIMATES CLOSER TO 6.0 OR 115 KT. THERE ARE NO APPARENT
ENVIRONMENTAL CONDITIONS WHICH SHOULD INHIBIT ADDITIONAL
INTENSIFICATION AS INDICATED BY THE SHIPS GUIDANCE.  THIS IS
REFLECTED IN THE OFFICIAL FORECAST WHICH MAKES JOHN A CATEGORY FOUR
HURRICANE WITHIN 12 HOURS...AND MAINTAINS JOHN AS A STRONG
HURRICANE THROUGH 5 DAYS.

THE INITIAL MOTION IS 290/9.  A WEST-NORTHWEST TO NORTHWEST MOTION
IS EXPECTED TO CONTINUE THROUGH 72 HOURS...AS THE HURRICANE IS
STEERED ALONG THE SOUTHWESTERN PERIPHERY OF A MID- TO UPPER-LEVEL
RIDGE BUILDING ACROSS NORTHERN MEXICO.  BOTH THE GFDL AND FSU
SUPERENSEMBLE GUIDANCE ARE TO THE EAST OF THE MODEL CONSENSUS AND
STILL FORECAST THE WESTERN EXTENT OF THE RIDGE TO BE FARTHER EAST
ALLOWING THE HURRICANE TO MOVE NORTHWESTWARD CLOSER TO THE WEST
COAST OF MEXICO AND EVENTUALLY TOWARD THE BAJA PENINSULA.  ON THE
OTHER HAND...THE GFS AND NOGAPS MODELS ARE TO THE WEST OF THE MODEL
CONSENSUS AND TAKE THE HURRICANE ON A MORE WEST-NORTHWEST TO WEST
TRACK RESULTING FROM A STRONGER RIDGE TO ITS NORTH.  THE OFFICIAL
FORECAST TRACK IS SLIGHTLY NORTH OF THE PREVIOUS ADVISORY AND
FOLLOWS THE DYNAMICAL MODEL CONSENSUS CONU CLOSELY. 
 
THE CONTINUED STRENGTHENING OF JOHN AND A COUPLE OF SHIP REPORTS
HAVE RESULTED IN AN EXPANSION OF THE WIND RADII.  THIS HAS PROMPTED
THE GOVERNMENT OF MEXICO TO ADJUST THE WATCHES AND WARNINGS ONCE
AGAIN.
   
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      29/2100Z 14.4N  99.7W   100 KT
 12HR VT     30/0600Z 15.0N 101.1W   115 KT
 24HR VT     30/1800Z 16.0N 103.0W   120 KT
 36HR VT     31/0600Z 17.3N 104.8W   120 KT
 48HR VT     31/1800Z 18.8N 106.8W   115 KT
 72HR VT     01/1800Z 21.0N 110.5W   110 KT
 96HR VT     02/1800Z 22.0N 113.0W   100 KT
120HR VT     03/1800Z 22.0N 116.0W    90 KT
 
$$
FORECASTER MAINELLI/PASCH
 
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