000
AXPZ20 KNHC 121601
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC MON SEP 12 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 EXTENDS FROM EXTREME SOUTHWEST CARIBBEAN W-NW 
ACROSS THE COSTA RICA NICARAGUA BORDER AND ENTERS THE EPAC 
WATERS NEAR 10.5N86W TO 10N102W TO 1011 MB LOW PRES AT 09N105W 
TO 14N112W TO 1010 MB LOW PRES AT 17N117W TO 11N124W TO 11N129W 
THEN ITCZ TO 1010 MB LOW PRES AT 11N136W TO BEYOND 09N140W. 
SCATTERED MODERATE TO STRONG CONVECTION IS NOTED ALONG THE 
MONSOON TROUGH AXIS FROM 08N TO 13N BETWEEN 88W AND 95W. 
ISOLATED MODERATE CONVECTION IS FROM 07N TO 10N BETWEEN 95W AND 
109W. SIMILAR CONVECTION IS FROM 08N TO 09N BETWEEN 122W AND 
127W. 

...DISCUSSION...

AT THE SURFACE...A WEAK HIGH PRES RIDGE CONTINUES JUST N OF THE 
NW WATERS PRODUCING MAINLY LIGHT TO MODERATE NE TRADEWINDS. A 
STATIONARY FRONT IS FURTHER W EXTENDING SW FROM 32N144W TO 
BEYOND 29N150W. 

BROAD CYCLONIC FLOW AROUND A TROPICAL WAVE CURRENTLY OVER THE NW 
CARIBBEAN HAS INDUCED NELY FLOW OVER THE SOUTHERN GULF OF 
MEXICO. THIS FLOW IS FUNNELING THROUGH THE CHIVELA PASS INTO THE 
GULF OF TEHUANTEPEC...RESULTING IN FRESH 20 KT WINDS. GUIDANCE 
SUGGESTS WINDS WILL INCREASE ACROSS THE GULF OF TEHUANTEPEC TO 
20 TO 25 KT THIS EVENING.

THE THREE LOW PRESSURE AREAS THAT ARE EMBEDDED WITHIN THE 
MONSOON TROUGH MENTIONED ABOVE CONTINUE TO SLOWLY WEAKEN AND ARE 
EXPECTED TO DISSIPATE WITHIN THE NEXT 48 HOURS.

NORTHERLY SWELLS...RESULTING IN COMBINED SEAS OF 8 FT...PREVAILS 
OVER THE WATERS N OF 23N BETWEEN 121W AND 136W. THESE SWELLS ARE 
EXPECTED TO SUBSIDE BELOW 8 FT TONIGHT. CROSS EQUATORIAL SW 
SWELL...WITH SEAS TO 9 FT...PREVAILS OVER MUCH OF THE AREA S OF 
10N W OF 93W. THIS SWELL EVENT WILL CONTINUE TO SPREAD NORTHWARD 
THROUGH THE FORECAST PERIOD REACHING THE COAST OF MEXICO S OF 
SOUTHERN BAJA CALIFORNIA TODAY.

$$
FORMOSA