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NOAA NOAA United States Department of Commerce

Hurricane JOHN


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HURRICANE JOHN DISCUSSION NUMBER  12
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP112006
200 AM PDT THU AUG 31 2006
 
THE EYE REMAINS OBSCURED IN INFRARED SATELLITE IMAGERY...BUT
SUCCESSIVE 0231 AND 0232 UTC MICROWAVE OVERPASSES AND THE
CUYUTLAN MEXICO RADAR CONTINUE TO DEPICT A WELL-DEFINED EYE...AND
THERE IS PLENTY OF VERY DEEP CONVECTION.  THE SOMEWHAT DEGRADED
SATELLITE APPEARANCE IS POSSIBLY DUE TO A LITTLE BIT OF WIND SHEAR
AND THE INTERACTION OF THE CIRCULATION WITH LAND.  THE INITIAL
INTENSITY IS MAINTAINED AT 110 KT BASED ON A BLEND OF THE VARIOUS
DVORAK ESTIMATES THAT RANGE FROM 100 TO 115 KT.  JOHN REMAINS A
DANGEROUS CATEGORY THREE HURRICANE ON THE SAFFIR-SIMPSON SCALE.
 
THE INTENSITY FORECAST REMAINS A CHALLENGE GIVEN THE CLOSE
PROXIMITY TO LAND.  THE OFFICIAL FORECAST TRACK IS SIMILAR TO THE
PREVIOUS ADVISORY AND KEEPS JOHN OFFSHORE FROM MAINLAND MEXICO BUT
NEAR OR OVER THE SOUTHERN BAJA CALIFORNIA PENINSULA IN ROUGHLY 36
HOURS.  THEREFORE...DUE TO THE VERY WARM WATERS...ADDITIONAL
STRENGTHENING IS POSSIBLE AND ONLY A SLIGHT AMOUNT OF STRENGTHENING
WOULD MAKE JOHN A CATEGORY FOUR HURRICANE...AND THIS POSSIBILITY IS
SUPPORTED BY ALL AVAILABLE INTENSITY GUIDANCE.  ONCE IT PASSES WEST
OF BAJA...COOLER WATERS SHOULD INDUCE A STEADY WEAKENING
TREND...BUT SINCE JOHN IS SO STRONG NOW IT WILL TAKE A WHILE FOR
THE CYCLONE TO SPIN DOWN LATE IN THE FORECAST PERIOD.  THE OFFICIAL
FORECAST KEEPS JOHN A TROPICAL STORM AT DAY 5.
 
THE INITIAL MOTION IS ABOUT THE SAME AS BEFORE...300/12...SO JOHN IS
RIGHT ON THE PREVIOUS ADVISORY TRACK.  GLOBAL MODELS REMAIN IN GOOD
AGREEMENT ON JOHN CONTINUING TO PARALLEL THE COAST OF MAINLAND
MEXICO ALONG THE SOUTHWESTERN PERIPHERY OF A MIDDLE- TO
UPPER-LEVEL RIDGE.  THE GFDL HAS SHIFTED A LITTLE BACK TO THE RIGHT
OR EAST AGAIN AND TAKES JOHN INLAND ALONG THE EAST COAST OF THE
GULF OF CALIFORNIA...BUT THE OTHER MODELS HAVE OVERALL CHANGED
LITTLE SINCE THE PREVIOUS CYCLE.  THE MODELS STILL DIVERGE AFTER
THE WESTWARD TURN NEAR SOUTHERN BAJA DUE TO DIFFERING SOLUTIONS FOR
THE UPPER TROUGH OFF THE WEST COAST OF THE UNITED STATES.  THE NEW
OFFICIAL FORECAST...LIKE THE PREVIOUS ADVISORY...PRESUMES THAT THE
MAJORITY OF THE MODELS ARE CORRECT IN BUILDING A MID-LEVEL RIDGE TO
THE NORTH OF JOHN THAT WILL TURN THE TROPICAL CYCLONE WESTWARD. 
THE GFDL CONTINUES TO INSIST OTHERWISE...WHICH KEEPS THE CONSENSUS
TRACKS SLOWER THAN THEY WOULD BE IN ITS ABSENCE.  PAYING SOME
ATTENTION TO THE GFDL SOLUTION...THE OFFICIAL FORECAST IS CLOSE TO
THE CONSENSUS ON THE WESTWARD PROGRESSION OF JOHN.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      31/0900Z 18.7N 105.3W   110 KT
 12HR VT     31/1800Z 20.0N 106.6W   115 KT
 24HR VT     01/0600Z 21.6N 108.0W   115 KT
 36HR VT     01/1800Z 22.7N 109.3W   115 KT
 48HR VT     02/0600Z 23.4N 110.6W   105 KT
 72HR VT     03/0600Z 24.0N 113.5W    90 KT
 96HR VT     04/0600Z 24.0N 117.5W    70 KT
120HR VT     05/0600Z 24.0N 122.0W    50 KT
 
$$
FORECASTER KNABB
 
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