000
AXPZ20 KNHC 171517
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SAT SEP 17 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

...ITCZ/MONSOON TROUGH...
MONSOON TROUGH FROM 9N85W 15N95W THEN CONTINUES FROM 21N109W 
13N115W TO 1011 MB LOW 11N132W TO 10N140W. SCATTERED MODERATE TO 
STRONG WITHIN 120 NM EITHER SIDE OF AXIS FROM 91W-95W AND WITHIN 
120 NM N OF AXIS FROM 109W-115W AND WITHIN 240 NM S OF AXIS FROM
115W-126W. SCATTERED MODERATE ISOLATED STRONG FROM 130W-140W

...DISCUSSION... 
UPPER LEVEL TROUGH EXTENDS FROM THE SW U.S. TO 32N118W 25N132W 
TO 16N140W. MODERATE TO STRONG SUBSIDENCE WITH DRY STABLE AIR AT 
THE MIDDLE AND UPPER LEVELS IS N OF 15N W OF 130W AND ELSEWHERE 
N OF 20N W OF 110W. AN UPPER LEVEL RIDGE IS BUILDING NW OF THE 
TROUGH AXIS. A BROAD UPPER LEVEL ANTICYCLONIC CIRCULATION IS 
CENTERED OVER WESTERN MEXICO NEAR 22N104W...WITH RIDGE EXTENDING 
WSW TO ANOTHER SMALLER ANTICYCLONIC CIRCULATION NEAR 17N124W.
UPPER LEVEL DIFFLUENCE S OF THE RIDGE AXIS IS ENHANCING 
CONVECTIVE ACTIVITY ALONG THE MONSOON TROUGH DESCRIBED ABOVE,

SURFACE 1024 MB HIGH PRES IS ANALYZED NEAR 34N135W WITH RIDGE 
COVERING THE AREA N OF 20N W OF 120W. A 1011 MB SURFACE LOW PRES 
IS CENTERED NEAR 11N132W DRIFTING SW. THE PRES GRADIENT BETWEEN 
THE LOW AND THE RIDGE IS PRODUCING ELY WINDS 20 KT AND SEAS TO 8 
FT FROM 13N-20N W OF 125W. THE PRES GRADIENT IS ALSO FORECAST TO 
TIGHTEN ACROSS SOUTHERN MEXICO LATER TODAY WITH NLY WINDS TO 20 
KT EXPECTED THROUGH THE GULF OF TEHUANTEPEC.

ELSEWHERE A BAND OF SW WINDS TO 20 KT AND SEAS TO 9 FT IN SW 
SWELL ARE FROM 9N-12N BETWEEN 110W-120W.
 
$$
DGS