000
AXPZ20 KNHC 050240
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC MON SEP 05 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0215 UTC.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM 10N86W TO 15N96W TO 12N116W TO 
14N130W TO 13N140W. THE INTERTROPICAL CONVERGENCE ZONE AXIS IS W 
OF AREA. SCATTERED MODERATE CONVECTION IS SEEN OVER THE GULF OF 
TEHUANTEPEC...FROM 07N TO 10N BETWEEN 95W AND 100W...AND FROM 
07N TO 10N BETWEEN 87W AND 90W. ISOLATED MODERATE CONVECTION IS 
N OF 10N AND S OF THE MONSOON TROUGH BETWEEN 121W AND 131W. 

...DISCUSSION...
A BROAD MIDDLE TO UPPER LEVEL TROUGH ENTERS THE FORECAST AREA 
NEAR 30N129W AND EXTENDS SSW TO NEAR 20N133W. UPPER LEVEL RIDGE 
EXTENDS FROM AN UPPER ANTICYCLONE CENTERED OVER THE NORTHERN 
PORTION OF THE GULF OF CALIFORNIA TO A COL NEAR 19N129W. ANOTHER 
RIDGE EXTENDS FROM THE SAME ANTICYCLONE ALONG MEXICO INTO THE 
BAY OF CAMPECHE. SOUTH OF THIS RIDGE...NE TO E FLOW ALOFT 
PERSISTS. A SECOND ANTICYCLONIC CIRCULATION IS NOTED JUST W OF 
AREA NEAR 15N141W. THE UPPER TROUGH IS FORECAST TO WEAKEN AND 
LIFT OUT TO THE NE. 

AT THE SURFACE...WEAK RIDGE...ANCHORED ON A 1017 MB HIGH NEAR 
24N130W...DOMINATES THE NW CORNER OF THE AREA PRODUCING MAINLY 
GENTLE BREEZE. A NEARLY STATIONARY 1013 MB LOW IS NEAR THE COAST 
OF NORTHERN CALIFORNIA WITH A FRONTAL TROUGH EXTENDING SW TO 
NEAR 26N140W. N SWELLS ARE NOTED IN THE WAKE OF THE FRONTAL 
TROUGH RAISING SEAS TO 8 FT PARTICULARLY N OF 28N W OF 132W. 
SEAS WILL SUBSIDE BELOW 8 FT LATE TONIGHT. TRADEWINDS REMAIN 
BELOW 20 KT E OF 140W UNDER THE INFLUENCE OF THIS WEAK 
RIDGE...WITH SEAS IN THE 6 TO 7 FT RANGE. THE SURFACE RIDGE IS 
FORECAST TO BUILD BACK IN ACROSS THE NW PART OF THE AREA BY LATE 
MON INTO TUE AS THE FRONTAL TROUGH WEAKENS. 

DISORGANIZED CLOUDINESS AND A FEW SHOWERS IN ASSOCIATION WITH 
THE REMNANTS OF T.D. EIGHT-E ARE EVIDENT ON VISIBLE SATELLITE 
IMAGERY ACROSS THE MOUTH OF THE GULF OF CALIFORNIA. THIS SYSTEM  
REMAINS EMBEDDED WITHIN THE S END OF THE SEMI-PERMANENT BAJA 
CALIFORNIA TROUGH AND IS FORECAST TO GRADUALLY WEAKEN DURING THE 
NEXT 24 HOURS.  

FURTHER SOUTH...LIMITED AREA OF FRESH 20 KT SW MONSOONAL FLOW IS 
FOUND FROM 08N TO 11N BETWEEN 100W AND 115W. THESE LOCALLY 
STRONGER MONSOONAL WINDS ARE INDUCING SPEED CONVERGENCE...AND 
CORRESPONDS WITH THE AREAS WHERE THERE IS ACTIVE CONVECTION. THE 
AREAL EXTENT AND STRENGTH OF THE MONSOONAL FLOW WILL LIKELY 
INCREASE BEGINNING LATE TUE. 

LONG PERIOD CROSS EQUATORIAL SWELL PREVAILS S OF 15N E OF 125W 
WITH COMBINED SEAS OF 8 TO 10 FT.

$$
GR