000
AXPZ20 KNHC 251539
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC MON JUL 25 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 AXIS FROM 08N78W TO 08N90W TO 09N103W. ITCZ AXIS 
FROM 09N103W TO 12N118W TO 09N130W TO BEYOND 08N140W. SCATTERED 
MODERATE TO ISOLATED STRONG CONVECTION IS NOTED WITHIN 150 NM S 
OF THE MONSOON TROUGH E OF 81W TO THE COAST OF COLOMBIA. SIMILAR 
CONVECTION CAN BE FOUND WITHIN 30 TO 60 NM EITHER SIDE OF THE 
MONSOON TROUGH FROM 86W AND 100W. SCATTERED MODERATE TO ISOLATED 
STRONG CONVECTION IS FROM 08N TO 13N BETWEEN 103W AND 111W. 
SCATTERED MODERATE CONVECTION IS FROM 06N TO 13N BETWEEN 117W 
AND 125W. 

...DISCUSSION...
A MID/UPPER LEVEL RIDGE EXTENDS FROM THE SW CONUS AND NORTHERN 
MEXICO ACROSS THE BAJA CALIFORNIA PENINSULA INTO THE EPAC 
DOMINATING THE N WATERS MAINLY N OF 18N E OF 120W. AN UPPER 
ANTICYCLONE IS NOTED NEAR 24N129W WITH A RIDGE SW TO NEAR 
13N138W. AN INVERTED UPPER TROUGH EXTENDS FROM 16N117W TO 
28N121W TO 15N125W AND SEPARATES THE TWO UPPER RIDGES. THIS 
TROUGH EXTENDS OVER THE FORMER TROPICAL CYCLONE DORA THAT IS 
ANALYZED AS A SURFACE TROUGH ON THE 25/1200 UTC SURFACE MAP. 
THE TROUGH EXTENDS FROM 26N115W TO 23N114W. AN EARLIER ASCAT 
PASS AND FEW SHIP OBSERVATIONS SHOWED N TO NW WINDS OF 10 TO 15 
KT ON THE WEST SIDE OF THE TROUGH AXIS. UPPER DIFFLUENCE ALONG 
THE SOUTHERN PERIPHERY OF THE RIDGES IS ENHANCING THE CONVECTION 
ALONG THE ITCZ BETWEEN 103W AND 125W. A BROAD UPPER RIDGE 
EXTENDS W OVER THE TROPICAL PACIFIC E OF 90W AND IS HELPING TO 
INDUCE CONVECTION ALONG AND SOUTH OF THE MONSOON TROUGH. 

AT THE LOW LEVELS A RIDGE EXTENDS FROM 32N140W TO 20N120W. 
18N115W. WEAK TRADE WINDS ARE NOTED BETWEEN THE RIDGE AND THE 
ITCZ. 

CROSS EQUATORIAL SE SWELLS...RESULTING IN SEAS TO 8 FT...ARE 
PROPAGATING NW ACROSS THE WATERS SW OF A LINE FROM 10N140W TO 
THE EQUATOR AT 105W. THIS SWELL WILL GRADUALLY DECAY THROUGH THE 
NEXT 24 HOURS AS A NEW SET OF CROSS EQUATORIAL SW SWELL MOVES 
NORTHWARD TO S OF 08N W OF 95W RAISING SEAS TO UP TO 10 FT. 

GAP WINDS...NE TRADES CONTINUE TO SURGE THROUGH THE GULF OF 
PAPAGAYO AT 15-20 KT THIS MORNING...THEN IS FORECAST TO DIMINISH 
TO 10-15 KT LATE TODAY. NORTHERLY WINDS ARE SURGING ACROSS THE 
GULF OF TEHUANTEPEC AT 20 TO 25 KT...BUT ARE EXPECTED TO 
DIMINISH BELOW 20 KT LATE TONIGHT. CURRENTLY...IXTEPEC IN THE 
STATE OF OAXACA MEXICO IS REPORTING SUSTAINED WINDS OF 20 KT. A 
JASON PASS CAPTURED SEAS TO NEAR 8 FT.  

LOOKING AHEAD...MARINE GUIDANCE SUGGESTS A GRADUAL INCREASE IN 
THE SW MONSOONAL FLOW MAINLY S OF 06N E OF 95W BEGINNING ON WED. 
EXPECT WINDS OF 20 TO 25 KT WITH BUILDING SEAS OF AROUND 11 FT.

$$
GR