000
WTPZ42 KNHC 180838
TCDEP2
 
HURRICANE GREG DISCUSSION NUMBER   7
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP072011
200 AM PDT THU AUG 18 2011

GREG HAS STRENGTHENED A LITTLE MORE SINCE THE LAST ADVISORY.  THE
CENTRAL DENSE OVERCAST HAS EXPANDED WITH AN INTERMITTENT WARM SPOT
EVIDENT IN INFRARED SATELLITE IMAGES.  A TRMM PASS AT 0436 UTC
SHOWED A WELL-DEFINED EYE IN THE MID-LEVELS BUT THIS FEATURE WAS
OBSCURED IN THE 37 GHZ CHANNEL.  THE INITIAL WIND SPEED IS
INCREASED TO 70 KT...IN AGREEMENT WITH DVORAK CLASSIFICATIONS FROM
TAFB AND SAB.  SOME ADDITIONAL STRENGTHENING IS LIKELY DURING THE
NEXT 12 TO 24 HOURS AS GREG REMAINS OVER WATERS WARMER THAN 26C AND
IN A LIGHT TO MODERATE WIND SHEAR ENVIRONMENT.  BEYOND 24 HOURS...
THE HURRICANE WILL TRACK OVER COOL WATERS AND INTO A MORE STABLE
ATMOSPHERE.  THESE FACTORS SHOULD CAUSE STEADY WEAKENING...AND GREG
IS FORECAST TO BECOME A POST-TROPICAL REMNANT LOW OVER 23C WATERS
BY THE END OF THE FORECAST PERIOD.

GREG CONTINUES TO RACE WEST-NORTHWESTWARD AT 18 KT DIRECTLY TO THE
SOUTH OF A MID-LEVEL HIGH OVER THE SOUTHWESTERN UNITED STATES.
GLOBAL MODELS SHOW THIS RIDGE WEAKENING DURING THE NEXT COUPLE OF
DAYS AS A TROUGH MOVES OVER THE WESTERN UNITED STATES.  THIS
PATTERN WILL CAUSE GREG TO SLOW DOWN BUT REMAIN ON A GENERAL
WESTWARD COURSE FOR THE NEXT SEVERAL DAYS.  OVERALL THE TRACK
GUIDANCE HAS CHANGED LITTLE FROM THE PREVIOUS CYCLE...AND THE
OFFICIAL FORECAST IS ESSENTIALLY AN UPDATE OF THE PREVIOUS ONE.
  
FORECAST POSITIONS AND MAX WINDS
 
INIT  18/0900Z 18.0N 109.9W   70 KT  80 MPH
 12H  18/1800Z 18.4N 112.2W   80 KT  90 MPH
 24H  19/0600Z 18.8N 114.8W   85 KT 100 MPH
 36H  19/1800Z 19.0N 116.9W   70 KT  80 MPH
 48H  20/0600Z 19.0N 118.7W   60 KT  70 MPH
 72H  21/0600Z 19.0N 121.6W   45 KT  50 MPH
 96H  22/0600Z 19.0N 124.0W   30 KT  35 MPH
120H  23/0600Z 19.0N 125.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
 
$$
FORECASTER CANGIALOSI