000
AXPZ20 KNHC 192134
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.

...SPECIAL FEATURE...
GREG WAS DOWNGRADED TO A TROPICAL STORM AT 1800 UTC...AND NOW
CONTINUES TO WEAKEN OVER COOLER WATERS. AT 19/2100 UTC...IT IS 
CENTERED NEAR 19.6N 117.0W MOVING W OR 280 DEGREES AT 10 KT. 
THIS GENERAL MOTION IS EXPECTED TO CONTINUE FOR THE NEXT COUPLE 
OF DAYS. MAXIMUM SUSTAINED WINDS ARE 50 GUSTS TO 60 KT. RAPID 
WEAKENING IS FORECAST DURING THE NEXT 48 HOURS AND THE SYSTEM IS 
EXPECTED TO BECOME A POST-TROPICAL REMNANT LOW PRESSURE BY 
SUNDAY. ESTIMATED MINIMUM CENTRAL PRES IS 994 MB. DEEP 
CONVECTION SURROUNDING THE CENTER HAS DECREASED SUBSTANTIALLY 
WITH ONLY A SMALL AREA OF MODERATE CONVECTION WITHIN 30 NM SE OF 
CENTER. REFER TO FORECAST ADVISORIES ISSUED UNDER WMO HEADER 
WTPZ22 KNHC AND AWIPS HEADER MIATCMEP2 FOR FURTHER DETAILS.

...ITCZ/MONSOON TROUGH...
MONSOON TROUGH FROM 12N86W TO 1008 MB LOW PRES NEAR 12N101W THEN 
RESUMES FROM 16N118W TO 11N140W. SCATTERED MODERATE CONVECTION 
IS WITHIN 120 NM S OF MONSOON TROUGH BETWEEN 118W AND 126W. 
SIMILAR CONVECTION IS ALSO NOTED FROM 06N TO 10N BETWEEN 83W AND 
89W.

...DISCUSSION...
WEAK SURFACE RIDGE DOMINATES THE NW CORNER OF THE FORECAST AREA. 
WINDS AND SEAS ASSOCIATED WITH THE MONSOON TROUGH ARE FAIRLY 
BENIGN EXCEPT FOR A SWATH OF 20 TO 25 KT WINDS EXTENDING SE OF 
GREG TO AROUND 12N115W. THE 1646 UTC ASCAT PASS PROVIDED 
OBSERVATIONS OF THESE WIND SPEEDS. THESE WINDS COINCIDE WITH A 
BAND OF CLOUDS ASSOCIATED IN PART WITH THE CIRCULATION OF GREG 
AND ALSO WITH THE MONSOONAL FLOW. EXPECT THIS TAIL OF HIGHER 
WINDS AND SEAS TO PROPAGATE WESTWARD ALONG WITH GREG OVER THE 
NEXT 12-24 HOURS. THEN...EXPECT INCREASING WINDS BETWEEN GREG 
AND THE RIDGE OVER THE NW CORNER OF THE AREA AS PRES GRADIENT 
TIGTHENS TO THE NW OF TROPICAL CYCLONE. 

AN AREA OF DISTURBED WEATHER...ANALYZED 1008 MB LOW PRES ON THE 
1800 UTC SURFACE MAP...IS LOCATED NEAR 12N101W OR ABOUT 280 NM 
SOUTH-SOUTHWEST OF ACAPULCO MEXICO. THIS SYSTEM IS PRODUCING AN 
EXTENSIVE AREA OF CLOUDINESS AND SHOWERS. SOME GRADUAL 
DEVELOPMENT OF THIS LARGE DISTURBANCE IS POSSIBLE OVER THE NEXT 
FEW DAYS AS IT MOVES TOWARD THE WEST-NORTHWEST AT ABOUT 15 MPH. 

VERY LITTLE CROSS EQUATORIAL SWELL IS EXPECTED THROUGH THE 
WEEKEND. 

$$
GR