Hurricane JOHN

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HURRICANE JOHN DISCUSSION NUMBER  13
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP112006
800 AM PDT THU AUG 31 2006
 
FIRST LIGHT VISIBLE IMAGERY REVEALS THAT JOHN HAS AN OBSCURED EYE
AND A DISTINCT EYEWALL...ABOUT 20 N MI WIDE.  THE CUYUTLAN MEXICO
RADAR CONTINUES TO SHOW A WELL-DEFINED EYE AS WELL AS RAIN BANDS
ALONG THE SOUTHWEST COAST OF MEXICO.  DVORAK INTENSITY ESTIMATES
FROM TAFB AND SAB WERE 115 KT AND 102 KT RESPECTIVELY...AND THE
INITIAL INTENSITY WILL BE HELD AT 110 KT.  JOHN REMAINS A DANGEROUS
CATEGORY THREE HURRICANE ON THE SAFFIR-SIMPSON HURRICANE SCALE. 
A UNITED STATES AIR FORCE RECONNAISSANCE AIRCRAFT IS SCHEDULED 
TO INVESTIGATE JOHN AT 1800 UTC...AND...IF NECESSARY...ADJUSTMENTS
TO THE INTENSITY WILL BE MADE IN THE NEXT ADVISORY.   

MOST OF THE INTENSITY GUIDANCE MAINTAINS JOHN AS A CATEGORY THREE TO
BORDERLINE CATEGORY FOUR HURRICANE THROUGH 36 TO 48 HOURS.  THE
DIFFICULTY IN FORECASTING THE INTENSITY IS PRIMARILY DUE TO THE
INTERACTION OF THE EASTERN SIDE OF THE HURRICANE WITH LAND.  SOME
ADDITIONAL STRENGTHENING IS ANTICIPATED IN THE FORECAST SINCE THE
SHEAR IS EXPECTED TO REMAIN RELATIVELY LIGHT AND WATERS WILL REMAIN
AROUND 30 DEGREES CELSIUS.  IN 72 HOURS...JOHN IS FORECAST TO MOVE
OVER WATERS BELOW 25 DEGREES CELSIUS AND STEADY WEAKENING TO A
TROPICAL STORM SHOULD OCCUR BY DAY 5.  

THE INITIAL MOTION IS 300/12.  JOHN HAS BEEN MOVING BETWEEN A WEST-
NORTHWEST AND NORTHWEST TRACK FOR THE LAST 24 HOURS. THIS GENERAL
MOTION SHOULD CONTINUE UNTIL THE HURRICANE APPROACHES THE SOUTHERN
TIP OF THE BAJA PENINSULA.  THE GLOBAL MODELS ARE IN GENERAL
AGREEMENT FOR THE FIRST 36 HOURS WITH JOHN CONTINUING TO MOVE ALONG
THE SOUTHWESTERN PERIPHERY OF A MIDDLE- TO UPPER-LEVEL RIDGE.  THE
MODELS DIVERGE IN FORECASTING THE STRENGTH OF THE RIDGE TO THE
NORTH OF THE CYCLONE AND EITHER TAKE JOHN ACROSS THE BAJA PENINSULA
OR REMAIN TO THE SOUTH.  THE GFS AND UKMET BOTH MAINTAIN ENOUGH
RIDGING TO THE NORTH OF THE HURRICANE WITHIN THE NEXT DAY OR SO TO
KEEP JOHN JUST TO THE SOUTH OF CABO SAN LUCAS.  HOWEVER...BOTH THE
GFDL AND NOGAPS MODELS CONTINUE TO INDICATE A LANDFALL ON THE
SOUTHERN BAJA PENINSULA.  THE OFFICIAL FORECAST TRACK FOLLOWS THE
CONSENSUS OF THE TRACK MODELS.

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      31/1500Z 19.5N 106.5W   110 KT
 12HR VT     01/0000Z 20.7N 107.6W   115 KT
 24HR VT     01/1200Z 22.0N 108.8W   115 KT
 36HR VT     02/0000Z 22.8N 110.1W   110 KT
 48HR VT     02/1200Z 23.3N 111.4W   100 KT
 72HR VT     03/1200Z 24.0N 114.0W    85 KT
 96HR VT     04/1200Z 24.0N 118.0W    65 KT
120HR VT     05/1200Z 24.0N 122.0W    45 KT
 
$$
FORECASTER MAINELLI/PASCH
 
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