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TROPICAL STORM GREG DISCUSSION NUMBER  10
NATIONAL WEATHER SERVICE MIAMI FL
2 PM PDT TUE SEP 07 1999
 
CONVECTION ASSOCIATED WITH GREG HAS DECREASED AND BECOME VERY
DISORGANIZED THIS AFTERNOON IN BOTH SATELLITE AND RADAR DATA.
SURFACE OBSERVATIONS FROM SAN JOSE DEL CABO HAVE SHOWN WINDS OF LESS
THAN TROPICAL STORM FORCE AND A LOWEST PRESSURE OF ABOUT 1003 MB.
SATELLITE INTENSITY ESTIMATES FROM TAFB AND SAB HAVE DECREASED TO 55
KT AND 45 KT RESPECTIVELY. GREG IS THUS DOWNGRADED TO A 50 KT
TROPICAL STORM.

GREG MOVED ALMOST DUE NORTH FOR A TIME TODAY...BUT HAS NOW TAKEN A
COURSE OF 330/4. THERE IS LITTLE CHANGE IN EITHER THE FORECAST
PHILOSOPHY OR THE FORECAST GUIDANCE FROM THE PREVIOUS PACKAGE. GREG
IS EXPECTED TO MOVE GENERALLY NORTHWEST UNDER THE MEXICAN RIDGE...
FOLLOWED BY A GRADUAL TURN TO THE WEST AS IT WEAKENS AND LOW LEVEL
STEERING BECOMES DOMINANT.

STRONG SHEAR HAS CAUSED GREG TO WEAKEN UP TO NOW...AND THE CYCLONE
WILL ENCOUNTER COLDER WATER AFTER CROSSING BAJA CALIFORNIA. THE TWO
NEGATIVE FACTORS SHOULD CAUSE FURTHER WEAKENING. THE INTENSITY
FORECAST CALLS FOR GREG TO BE DISSIPATING BY 72 HOURS. THERE IS A
CHANCE IT COULD WEAKEN MORE RAPIDLY THAN FORECAST HERE.
 
BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     07/2100Z 23.0N 109.7W    50 KTS
12HR VT     08/0600Z 23.4N 110.2W    40 KTS
24HR VT     08/1800Z 23.9N 111.1W    35 KTS
36HR VT     09/0600Z 24.3N 112.5W    30 KTS
48HR VT     09/1800Z 24.5N 114.0W    25 KTS
72HR VT     10/1800Z 24.5N 117.0W    25 KTS...DISSIPATING
 
 
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