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WTPA42 PHFO 301500
TCDCP2
TROPICAL STORM JOHN DISCUSSION NUMBER   9
NATIONAL WEATHER SERVICE HONOLULU HI
5 AM HST WED AUG 30 2000
 
JOHN IS HANGING IN THERE IN SPITE OF THE MODERATE TO STRONG
SOUTHWEST SHEAR IT IS ENCOUNTERING.  THE INITIAL INTENSITY OF 55 KT
IS BASED ON A SATELLITE INTENSITY ESTIMATE WITH A DVORAK T NUMBER OF
3.5 FROM WFO HONOLULU AND SAB. DEEP CONVECTION IS ON THE UPSWING
THOUGH LIMITED TO THE NORTHEAST QUADRANT. OUTFLOW IS GOOD IN THE
NORTH SEMICIRCLE AND FAIR BUT GETTING BETTER ELSEWHERE.
 
CURRENT MOTION ESTIMATE IS 285/04 WHICH IS SLOWER THAN 6 HOURS AGO.
THE NORTH PACIFIC HIGH AT 45N IS CENTERED FAR NORTH OF ITS MEAN
POSITION FOR THE SUMMER MONTHS MAKING FOR WEAK STEERING WINDS DOWN
AT 17N. JOHN SHOULD MOVE WEST AT ABOUT 4 KT FOR ANOTHER 24 HOURS
THEN SLOW DOWN SOME MORE. THE STEERING WINDS ARE FORECAST TO
COLLAPSE AFTER 24 HOURS AS AN UPPER-LEVEL TROUGH TO THE NORTHEAST
DIGS TO THE SOUTHWEST AND ERODES THE TRADES FROM ABOVE.  AT THIS
POINT THE MODELS VARY GREATLY WITH LBAR P91E AND BAMD TAKING THE
SYSTEM TO THE NORTHEAST...CLIPER TAKES IT TO THE NORTHWEST...AND
EVERYBODY ELSE CURVES IT AROUND TO THE SOUTHEAST. WILL GO WITH THE
MAJORITY AND LOOP JOHN SLOWLY AROUND TO THE SOUTHEAST AS IT WAITS
FOR THE TRADES TO REBUILD.
 
ALL MODELS WEAKEN JOHN OVER THE NEXT 72 HOURS. WITH THE SYSTEM
STAYING OVER MARGINALLY WARM 26C WATER AND WITH THE SHEAR POSSIBLY
DECREASING WE WILL KEEP JOHN AT 55 KT THEN WEAKEN HIM AFTER 24 HOURS
AS WESTERLY SHEAR KICKS IN. CRAIG
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     30/1500Z 17.5N 141.2W    55 KTS
12HR VT     31/0000Z 17.7N 141.8W    55 KTS
24HR VT     31/1200Z 17.7N 142.6W    55 KTS
36HR VT     01/0000Z 17.4N 143.2W    50 KTS
48HR VT     01/1200Z 16.9N 143.5W    45 KTS
72HR VT     02/1200Z 16.0N 142.8W    40 KTS