Tropical Storm JOHN

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TROPICAL STORM JOHN DISCUSSION NUMBER   3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP112006
800 PM PDT MON AUG 28 2006
 
JOHN HAS CONTINUED TO STRENGTHEN OVER THE LAST 6 HOURS WITH VIGOROUS
CONVECTION WRAPPING AROUND THE ESTIMATED CENTER. IN FACT...THE
LATEST MICROWAVE IMAGERY INDICATES A BANDING EYE MAY BE FORMING.
DVORAK INTENSITY ESTIMATES HAVE INCREASED TO 45 AND 55 KT FROM TAFB
AND SAB RESPECTIVELY. THE INITIAL INTENSITY ESTIMATE OF 55 KT IS SET
AT THE HIGH END OF THIS RANGE AND IS CLOSE TO THE UW-CIMSS RAW ADT
VALUES BASED ON THE MUCH IMPROVE SATELLITE APPEARANCE.  JOHN
APPEARS TO BE LOCATED WITHIN A NEAR OPTIMAL ENVIRONMENT FOR FURTHER
STRENGTHENING.  ALL AVAILABLE INTENSITY GUIDANCE SHOWS JOHN
BECOMING AT CATEGORY TWO HURRICANE WITHIN 48 HOURS AND THE SHIPS
MODEL INDICATES A 50 PERCENT PROBABILITY OF RAPID INTENSIFICATION
OVER THE NEXT 24 HOURS.  ACCORDINGLY...THE OFFICIAL FORECAST BRING
JOHN CLOSE TO MAJOR HURRICANE STRENGTH BY 48 HOURS.  
 
THE INITIAL MOTION ESTIMATE OF 290/06 IS BASED ON A RECENT AMSR-E
MICROWAVE FIX AT 1937 UTC.  JOHN IS EXPECTED TO CONTINUE MOVING ON
A GENERAL NORTHWESTWARD MOTION FOR THE NEXT 72 HOURS. A GRADUAL
INCREASE IN SPEED IS EXPECTED AS JOHN MOVES AROUND THE SOUTHWESTERN
PERIPHERY OF A MIDDLE- TO UPPER-LEVEL RIDGE FORECAST TO BUILD OVER
NORTHERN MEXICO.  THERE IS SOME SPREAD IN THE MODEL TRACK GUIDANCE
WITH THE GFDL BEING ON THE FAR RIGHT OR EAST SIDE OF THE MODEL
SUITE AND THE GFS BEING ON THE FAR LEFT OR WEST SIDE.  THE GFS
ANALYSIS OF JOHN APPEARS MUCH TOO WEAK AND SHALLOW...RESULTING IN
A DUE WEST MOTION INITIALLY.  THIS SOLUTION APPEARS LESS
LIKELY...THEREFORE THE OFFICIAL FORECAST IS JUST TO THE RIGHT OF
THE MODEL CONSENSUS OUT OF RESPECT FOR THE GFDL MODEL.  

THE OFFICIAL TRACK FORECAST SHOWS JOHN PARALLELING THE COAST OF
MEXICO FOR THE NEXT 48 HOURS.  GIVEN THE CLOSE PROXIMITY OF THE
TRACK TO THE COAST AND THE INHERENT UNCERTAINTY IN THE TRACK
FORECAST...A TROPICAL STORM WATCH IS NOW NECESSARY FOR PORTIONS OF
THE MEXICAN COAST.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      29/0300Z 13.9N  97.3W    55 KT
 12HR VT     29/1200Z 14.3N  98.3W    65 KT
 24HR VT     30/0000Z 14.8N  99.7W    80 KT
 36HR VT     30/1200Z 15.5N 101.5W    90 KT
 48HR VT     31/0000Z 16.3N 103.4W    95 KT
 72HR VT     01/0000Z 19.4N 108.0W    95 KT
 96HR VT     02/0000Z 21.5N 112.0W    85 KT
120HR VT     03/0000Z 22.0N 115.0W    60 KT
 
$$
FORECASTER RHOME/FRANKLIN
 
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