000
AXPZ20 KNHC 172115
TWDEP 

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

...ITCZ/MONSOON TROUGH...
MONSOON TROUGH FROM 9N85W 15N95W THEN CONTINUES FROM 21N109W 
13N115W TO 1010 MB LOW 11N133W TO 09N140W. SCATTERED MODERATE TO 
STRONG WITHIN 220 NM S OF AXIS FROM 94W-97W AND WITHIN 90 NM N 
OF AXIS FROM 110W-114W AND WITHIN 240 NM S OF AXIS FROM 
119W-130W.

...DISCUSSION... 
UPPER LEVEL TROUGH EXTENDS FROM A CYCLONIC CIRCULATION JUST N OF 
THE AREA NEAR 34N132W WITH TROUGH TO 32N132W O 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 OFF THE WEST 
COAST OF MEXICO NEAR 21N107W...WITH RIDGE EXTENDING WSW TO 
13N140W. UPPER LEVEL DIFFLUENCE S OF THE RIDGE AXIS IS ENHANCING 
CONVECTIVE ACTIVITY ALONG THE MONSOON TROUGH DESCRIBED ABOVE,

SURFACE RIDGE COVERS THE AREA N OF 15N W OF 115W. A 1010 MB 
SURFACE LOW PRES IS CENTERED NEAR 11N133W DRIFTING SW. THE PRES 
GRADIENT BETWEEN THE LOW AND THE RIDGE IS PRODUCING ELY WINDS 20 
KT AND SEAS TO 8 FT WITHIN 240 NM N SEMICIRCLE OF THE LOW. THE 
PRES GRADIENT HAS ALSO TIGHTENED ACROSS SOUTHERN MEXICO WITH NLY 
WINDS TO 20 KT 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