000
AXPZ20 KNHC 041533
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SUN SEP 04 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...
THE MONSOON TROUGH EXTENDS FROM 12N86W TO 16N100W TO 13N115W TO 
14N130W TO 13N140W. NO INTERTROPICAL CONVERGENCE ZONE AXIS IS 
NOTED. SCATTERED MODERATE ISOLATED STRONG FROM 09N TO 12N 
BETWEEN 105W TO 124W AND WITHIN 60-120 NM S OF MONSOON TROUGH 
BETWEEN 125W AND 129W.

...DISCUSSION...
AN UPPER LEVEL TROUGH PREVAILS OVER THE NW PART OF THE AREA. 
ASSOCIATED WITH THE UPPER TROUGH IS A SURFACE TROUGH EXTENDING 
FROM 30N132W TO 27N140W. THIS SURFACE TROUGH HAS REPLACED 
SURFACE RIDGING OVER THE NW PART OF THE AREA WHICH HAS RESULTED 
IN A WEAKER PRESSURE GRADIENT OVER THE WESTERN PART OF THE 
AREA...AND WINDS LESS THAN 20 KT. SURFACE RIDGE IS NOT EXPECTED 
TO BUILD BACK IN ACROSS THE NW PART OF THE AREA UNTIL TUE. THIS 
WILL KEEP THE PRESSURE GRADIENT RELATIVELY WEAK OVER THE WEST 
PART OF THE AREA...AND TRADE WINDS LESS THAN 20 KT THROUGH THE 
FORECAST PERIOD. 

LIMITED AREA OF FRESH 20 KT SW MONSOONAL FLOW IS FOUND FROM 09N 
TO 12N BETWEEN 100W AND 115W. THESE LOCALLY STRONGER MONSOONAL 
WINDS ARE INDUCING SPEED CONVERGENCE...AND CORRESPONDS WITH THE 
AREAS WHERE THERE IS ACTIVE CONVECTION. ASIDE FROM THIS...CROSS 
EQUATORIAL SW SWELL GENERALLY PREVAILS S OF 15N E OF 125W. 

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AL