000
AXPZ20 KNHC 180910
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC THU AUG 18 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0900 UTC.

...SPECIAL FEATURES...
TROPICAL STORM FERNANDA AT 13.4N 139.9W 994 MB AT 0900 UTC AUG 
18 MOVING NW OR 320 DEG AT 13 KT. MAXIMUM SUSTAINED WIND 55 
GUSTS 65 KT. NUMEROUS STRONG CONVECTION WITHIN 90 NM OF CENTER. 
FERNANDA EXPECTED TO MOVE W OF THE DISCUSSION AREA LATER THIS 
MORNING. REFER TO FORECAST ADVISORIES ISSUED UNDER WMO HEADER 
WTPZ21 KNHC AND AWIPS HEADER MIATCMEP1 FOR FURTHER DETAILS.

HURRICANE GREG AT 18.0N 109.9W 985 MB AT 0900 UTC AUG 18 MOVING 
W-NW OR 285 DEG AT 18 KT. MAXIMUM SUSTAINED WINDS 70 GUSTS 85 
KT. NUMEROUS STRONG CONVECTION WITHIN 90 NM N AND 150 NM S 
SEMICIRCLES. GREG SHOULD CONTINUE TO INTENSIFY OVER WARM WATERS 
S OF MEXICO DURING THE NEXT TWO DAYS. REFER TO FORECAST 
ADVISORIES ISSUED UNDER WMO HEADER WTPZ22 KNHC AND AWIPS HEADER 
MIATCMEP2 FOR FURTHER DETAILS.

...ITCZ/MONSOON TROUGH...
MONSOON TROUGH 16N113W 12N128W. SCATTERED TO STRONG CONVECTION 
WITHIN 180 NM N OF AXIS FROM 117W-119W.

...DISCUSSION...
UPPER LEVEL TROUGH ACROSS THE FAR NW PORTION OF THE DISCUSSION 
AREA...N OF 26N W OF 133W. MODERATE TO STRONG SUBSIDENCE WITH 
DRY STABLE AIR AT THE MIDDLE AND UPPER LEVELS IS N OF 15N W OF 
130W. AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED NEAR 
27N121W WITH RIDGE SW TO 17N135W. A WEAK UPPER LEVEL INVERTED 
TROUGH FROM CENTRAL BAJA TO 22N120W SEPARATES THE ABOVE 
MENTIONED ANTICYCLONE FROM ANOTHER ANTICYCLONIC CIRCULATION SW 
OF THE TIP OF THE BAJA PENINSULA NEAR 22N113W. A SLY 45-50 KT 
WIND MAX IS W OF THE ANTICYCLONIC CIRCULATION FROM 25N128W TO 
32N125W. THE TROUGH IS FORECAST TO DEVELOP INTO A CYCLONIC 
CIRCULATION TONIGHT. UPPER LEVEL DIFFLUENT FLOW SW OF THE 
ANTICYCLONIC CIRCULATION IS AIDING THE CONVECTION ASSOCIATED 
WITH HURRICANE GREG.

SURFACE HIGH RIDGE EXTENDS FROM 32N135W SE TO 26N125W. WINDS 
REMAIN LIGHT TO MODERATE OVER MOST OF BASIN EXCEPT THOSE AREAS 
ASSOCIATED WITH TROPICAL CYCLONES OR LOW PRES CENTERS. THE CROSS 
EQUATORIAL SLY SWELL HAS SUBSIDED. BROKEN TO OVERCAST 
STRATOCUMULUS BLANKET THE AREA N OF 17N W OF 120W.

$$
DGS