000
WTPZ42 KNHC 182049
TCDEP2
 
HURRICANE GREG DISCUSSION NUMBER   9
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP072011
200 PM PDT THU AUG 18 2011

GREG HAS CHANGED LITTLE IN ITS APPEARANCE ON SATELLITE IMAGERY IN
THE PAST SIX HOURS WITH OCCASIONAL HINTS OF AN EYE APPEARING IN
VISIBLE IMAGERY. OUTFLOW REMAINS GOOD OVER THE SOUTHWESTERN
SEMICIRCLE AND RATHER POOR TO THE NORTHEAST. AS A RESULT OF THIS
AND POSSIBLE DRY AIR ENTRAINMENT...THE CORE OF THE SYSTEM IS
DETACHED FROM THE DEEP CONVECTIVE BAND TO THE SOUTHEAST AND SOUTH.
INTENSITY ESTIMATES FROM TAFB AND SAB BOTH CAME IN AT 77 KT...AND
THE INITIAL INTENSITY HAS BEEN HELD AT 75 KT.

THE INITIAL MOTION IS 285/12 WHICH IS SLIGHTLY SLOWER THAN SIX HOURS
AGO. GREG REMAINS LOCATED BETWEEN A LARGE MID- TO UPPER-LEVEL RIDGE
EXTENDING FROM THE NORTHEAST PACIFIC OFF NORTHERN CALIFORNIA TO
NORTHWESTERN MEXICO AND A LARGE GYRE IN THE INTERTROPICAL
CONVERGENCE ZONE TO ITS SOUTHWEST. MOST DYNAMICAL MODELS FORECAST
GREG TO SLOW AND MAKE A GRADUAL TURN TO THE WEST IN THE NEXT 24 TO
48 HOURS AS THE NORTHEAST PACIFIC RIDGE REMAINS IN PLACE AND GREG
INTERACTS WITH THE WEAK GYRE TO ITS SOUTHWEST. BEYOND 48 HOURS THE
TRACK HAS BEEN NUDGED SLIGHTLY TO THE SOUTH TO BE IN BETTER
AGREEMENT WITH THE CONSENSUS MODELS.

THE INTENSITY OF GREG HAS LIKELY PLATEAUED AND IS NOT EXPECTED TO
CHANGE MUCH IN THE NEXT 12 HOURS. BEYOND 12 HOURS...GREG IS
FORECAST TO MOVE OVER INCREASINGLY COOLER WATERS WHICH WILL CAUSE
STEADY WEAKENING.  GREG IS FORECAST TO BECOME A POST-TROPICAL
REMNANT LOW IN ABOUT 5 DAYS.  THE FORECAST INTENSITIES HAVE BEEN
NUDGED DOWNWARD FROM THE PREVIOUS FORECAST TO BE IN BETTER
AGREEMENT WITH GUIDANCE.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  18/2100Z 18.8N 112.6W   75 KT  85 MPH
 12H  19/0600Z 19.0N 114.6W   75 KT  85 MPH
 24H  19/1800Z 19.1N 116.9W   70 KT  80 MPH
 36H  20/0600Z 19.1N 119.0W   60 KT  70 MPH
 48H  20/1800Z 18.9N 120.7W   50 KT  60 MPH
 72H  21/1800Z 18.5N 123.0W   35 KT  40 MPH
 96H  22/1800Z 18.5N 125.5W   25 KT  30 MPH
120H  23/1800Z 18.0N 128.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
 
$$
FORECASTER BEVEN/WROE