000
AXPZ20 KNHC 061552
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC TUE SEP 06 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 10N84W TO 13N90W TO LOW PRES AT 
19N108W TO LOW PRES AT 11N124W TO 09N140W. SCATTERED MODERATE 
AND ISOLATED STRONG CONVECTION IS WITHIN 120 NM OF A LINE FROM 
06N83W TO 12N90W AND ALSO N OF 08N BETWEEN 92W AND 106W...AND 
WITHIN 90 NM LINE FROM 09N106W TO 09N115W TO 13N124W.

...DISCUSSION...

A BROAD UPPER LEVEL TROUGH OVER THE NW CORNER OF THE AREA 
CONTINUES TO WEAKEN AND LIFT OUT TO THE NE. A LARGE UPPER LEVEL 
ANTICYCLONE IS OVER NORTHERN MEXICO NEAR 28N105W WITH A RIDGE 
AXIS EXTENDING TO A SMALLER UPPER LEVEL ANTICYCLONE TO THE SW 
NEAR 24N124W CONTINUING TO A COL NEAR 21N136W. DRY AND STABLE 
AIR UNDER MODERATE TO STRONG SUBSIDENCE IS NOTED ON WATER VAPOR 
SATELLITE IMAGERY N OF 15N W OF 120W.

NE TO E FLOW ALOFT PERSISTS S OF THE UPPER LEVEL RIDGE MENTIONED 
ABOVE ACROSS THE MAJORITY OF THE REMAINDER OF THE DISCUSSION 
AREA. UPPER LEVEL DIFFLUENCE S OF THE RIDGE AXIS IS HELPING TO 
SUPPORT CONVECTION NEAR THE MONSOON TROUGH AS DESCRIBED ABOVE.

AT THE SURFACE...A BROAD RIDGE OF HIGH PRES COVERS THE AREA N OF 
15N W OF 115W. WITH A WEAK PRES PATTERN IN PLACE TRADES REMAIN 
LESS THAN 20 KT ACROSS THE NE PACIFIC WATERS. AN AREA OF 20 KT 
SW WINDS EXISTS FROM 08N TO 11N BETWEEN 95W AND 105W ALONG WITH 
9 TO 10 FT SEAS IN SW SWELL. THESE WINDS ARE FORECAST TO MOVE 
FROM 06N TO 12N BETWEEN 100W AND 123W WITH SEAS BUILDING TO 9 TO 
11 FT IN 24 HOURS...THEN FROM 06N TO 12N BETWEEN 107W AND 117W 
IN 48 HOURS.

1007 MB LOW PRES IS NEAR 19N108W. AN AREA OF NE TO E 20 TO 25 KT 
WINDS WILL COMMENCE IN 24 HOURS N OF 15N BETWEEN 95W AND 98W DUE 
TO A TIGHTENING PRES GRADIENT ALONG THE CENTRAL COAST OF MEXICO 
AS THIS LOW EMBEDDED IN THE MONSOON TROUGH STRENGTHENS SLIGHTLY. 
THESE WINDS WILL THEN PERSIST THROUGH 48 HOURS IN THE SAME AREA.
1011 MB LOW PRES IS NEAR 11N124W. THIS LOW WILL REMAIN NEARLY 
STATIONARY THROUGH THE NEXT 48 HOURS WITH NO SIGNIFICANT 
DEVELOPMENT EXPECTED.

OTHERWISE...LONG PERIOD CROSS EQUATORIAL SWELL OF 8 TO 10 FT 
CONTINUES TO DOMINATE THE REMAINDER OF THE AREA S OF 18N BETWEEN 
90W AND 125W AND ALSO S OF 07N BETWEEN 78W AND 87W. THESE SWELLS 
WILL NOT VARY MUCH THROUGH THE NEXT 48 HOURS. BROKEN TO OVERCAST 
STRATOCUMULUS CLOUDS BLANKET THE AREA N OF 18N W OF 120W.

$$
LEWITSKY