HOME	PRODUCTS	FORECASTS	IMAGERY	ABOUT TPC	RECONNAISSANCE

WTPA42 PHFO 300900
TCDCP2
TROPICAL STORM JOHN DISCUSSION NUMBER   8
NATIONAL WEATHER SERVICE HONOLULU HI
11 PM HST TUE AUG 29 2000
 
JOHN APPEARS TO BE MAINTAINING STRENGTH IN SPITE OF THE MODERATE TO
STRONG SOUTHWESTERLY 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 THE HONOLULU WFO. SAB CAME IN WITH A T
NUMBER OF 3.0 OR 45 KT. DEEP CONVECTION HAS SHRUNK SOME OVER THE
LAST 6 HOURS AND IS LIMITED TO THE NORTH AND NORTHEAST QUADRANTS.
OUTFLOW REMAINS GOOD IN THE NORTH SEMICIRCLE AND FAIR ELSEWHERE.

CURRENT MOTION ESTIMATE IS 295 AT 6 KT. WITH THE NORTH PACIFIC HIGH
CENTERED WELL NORTH OF ITS MEAN POSITION FOR THIS TIME OF YEAR...THE
TRADES ARE BARELY STRONG ENOUGH TO KEEP JOHN PLUGGING ALONG ON A
MORE OR LESS WESTWARD TRACK. AFTER ABOUT 36 HOURS...THE STEERING
WINDS ARE FORECAST TO COLLAPSE AS AN UPPER-LEVEL TROUGH TO THE
NORTHEAST RETROGRADES TO THE SOUTHWEST. AT THIS POINT THE MODELS
VARY GREATLY WITH SOME TAKING THE SYSTEM TO THE NORTHEAST AND OTHERS
TO THE SOUTHEAST. WILL STICK WITH THE PREVIOUS FORECAST SOLUTION
LOOPING JOHN SLOWLY TO THE SOUTHEAST AS IT WAITS FOR THE TRADES TO
REBUILD.

ALL MODELS GRADUALLY WEAKEN JOHN OVER THE NEXT 72 HOURS. WITH THE
SYSTEM STAYING OVER MARGINALLY WARM 26C SSTS AND WITH DECREASING
SHEAR EXPECTED WE WILL KEEP JOHN AT 55 KT FOR ANOTHER 24 TO 30 HOURS
THEN WEAKEN THE SYSTEM AFTER WESTERLY SHEAR KICKS IN.
CRAIG
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     30/0900Z 17.3N 141.0W    55 KTS
12HR VT     30/1800Z 17.5N 141.7W    55 KTS
24HR VT     31/0600Z 17.6N 142.6W    55 KTS
36HR VT     31/1800Z 17.4N 143.4W    50 KTS
48HR VT     01/0600Z 17.0N 143.7W    45 KTS
72HR VT     02/0600Z 16.2N 142.8W    40 KTS