000
AXPZ20 KNHC 190310
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC FRI AUG 19 2011

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS 
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0300 UTC.

...SPECIAL FEATURES...
HURRICANE GREG AT 18.5N 111.5W AT 19/0300 UTC MOVING W-NW AT 16 
KT.  MAXIMUM SUSTAINED WIND SPEED 75 GUSTS TO 90 KT WITH MINIMUM 
CENTRAL PRES 980 MB.  NUMEROUS STRONG CONVECTION WITHIN 90 NM NE 
SEMICIRCLE AND 150 NM SW SEMICIRCLE.  GREG HEADS FOR THE PACIFIC 
OPEN OCEAN WHERE COOLER WATER TEMPERATURES ARE EXPECTED TO START 
ITS WEAKENING FATE.  REFER TO FORECAST ADVISORIES ISSUED UNDER 
WMO HEADER WTPZ22 KNHC AND AWIPS HEADER MIATCMEP2 FOR FURTHER 
DETAILS.

...ITCZ/MONSOON TROUGH...
MONSOON TROUGH ANALYZED FROM 12N87W TO 09N103W...THEN RESUMES 
FROM 16N116W TO 12N131W.  SCATTERED MODERATE TO ISOLATED STRONG 
CONVECTION WITHIN 90 NM OF AXIS E OF 103W AND WITHIN 150 NM OF 
AXIS FROM 121W TO 128W.

...DISCUSSION...
UPPER LEVEL TROUGH CROSSES FAR NW PORTION OF BASIN FROM 32N135W 
TO 23N140W.  TROUGH INTRODUCES DRY SUBSIDING AIR MASS N OF 20N W 
OF 120W IN AN OTHERWISE MOIST E PAC.  LARGE UPPER LEVEL RIDGE 
OVER TEXAS BRINGS STEADY ANTICYCLONIC FLOW OVER MOST OF THE 
REMAINDER OF BASIN INCLUDING A SMALL GYRE OVER GREG.  A WEAK 
TROUGH ALOFT OVER BAJA CALIFORNIA ENCROACHES INTO E PAC JUST N 
OF GREG.

ELSEWHERE AT THE LOWER LEVELS...
HIGH PRES CENTER 1029 MB WELL N OF E PAC STEERS GREG INTO A MORE 
WESTERLY TRACK AND INTO COOLER WATER TEMPERATURES WHERE ITS 
ENERGY SOURCE WOULD BE CUT OFF.  LOW PRES ALONG MONSOON TROUGH 
FORCES FRESH TO STRONG WINDS SW WINDS FROM 08N TO 15N BETWEEN 
104W AND 12W.  

$$
WALLY BARNES