000
AXPZ20 KNHC 210317
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC WED JUL 21 2010

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN
FROM THE EQUATOR TO 32N...EAST OF 140W.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 0115 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE WAS ANALYZED FROM 13N90W TO 
10N110W TO 12N120W TO 13N126W TO 09N140W. SCATTERED MODERATE 
CONVECTION IS WITHIN 120 NM EITHER SIDE OF THE ITCZ AXIS BETWEEN 
102W AND 112W...WITHIN 270 NM S OF THE ITCZ AXIS BETWEEN 118W 
AND 122W AND WITHIN 120 NM N AND 90 NM S OF THE ITCZ AXIS W OF 
137W.

...DISCUSSION...

AN UPPER LEVEL RIDGE ENTERS THE AREA FROM 24N140W TO 30N134W 
WITH VERY DRY AIR IN PLACE W OF 135W. AN UPPER LEVEL LOW IS 
CENTERED NEAR 30N128W AND EXTENDS A TROUGH TO 18N135W WITH MID 
TO UPPER LEVEL MOISTURE EVIDENT N OF 24N BETWEEN 125W AND 135W. 
THIS UPPER TROUGH IS EXPECTED TO REMAIN NEARLY STATIONARY DURING 
THE NEXT 48 HOURS. TO THE S...AN ANTICYCLONE IS NEAR 11N134W. 
DIFFLUENT FLOW ALOFT ON THE SW SIDE OF THE LOW IS ENHANCING 
CONVECTION ALONG THE W END OF THE ITCZ. AN UPPER LEVEL 
ANTICYCLONE IS POSITIONED NEAR 21N117W WITH A RIDGE SW TO NEAR 
15N125W. AN UPPER LEVEL CYCLONE IS JUST NE OF THIS ANTICYCLONE 
NEAR 24N113W. DEEP LAYERED MOISTURE IS MOVING N OF THIS UPPER 
CYCLONE UP THE GULF OF CALIFORNIA AND ACROSS BAJA CALIFORNIA AND 
NW MEXICO. OTHERWISE THE REMAINDER OF THE UPPER LEVEL FLOW 
PATTERN IS DOMINATED BY E-NE WINDS WITH ABUNDANT MOISTURE 
ADVECTING FROM CARIBBEAN SEA INTO THE E PAC FEEDING SCATTERED 
MODERATE CONVECTION ALONG AND JUST OFFSHORE OF MUCH OF THE 
MEXICAN AND CENTRAL AMERICAN COAST S OF 20N.

1040 MB HIGH PRES AT THE SURFACE IS CENTERED WELL NW OF THE 
DISCUSSION AREA NEAR 45N152W WITH A RIDGE AXIS EXTENDING TO 
30N133W AND TO 15N110W WITH VERY DRY AND STABLE AIR UNDERNEATH 
IT. A WEAK TROUGH...THE REMNANTS OF T.D. SIX-E...LINGERS FROM 
20N127W TO 17N130W WITH NO CONVECTION EVIDENT WITH THIS FEATURE. 
REGENERATION OF THIS SYSTEM IS NOT ANTICIPATED.

GALE FORCE WINDS ALONG THE PACIFIC NW COAST OF THE U.S. CONTINUE 
TO GENERATE NORTHERLY SWELL IN THE 8 TO 10 FT RANGE INTO THE 
DISCUSSION AREA N OF 22N BETWEEN 119W AND 132W. SHIPS 3FMH7 
REPORTING 10 FT NEAR 25N131W AND LAXP4 REPORTING 8 FT NEAR 
30N120W AT 0000 UTC CONFIRMED THESE CONDITIONS. THIS SWELL WILL 
CONTINUE...KEEPING SEAS TO 9 FT PRIMARILY IN THE AREA N OF 25N 
BETWEEN 120W AND 135W WED AND SUBSIDING TO 8 FT THU.

LONG PERIOD CROSS EQUATORIAL SOUTHERLY SWELL OF 8 TO 10 FT LIES 
ACROSS THE S PORTION OF THE BASIN PRIMARILY S OF 12N BETWEEN 90W 
AND 135W WITH SW SWELL TO 8 FT IN THE FAR SE PORTION. THIS SWELL 
WILL GRADUALLY DECAY OVER THE NEXT TWO DAYS...BUT A NEW SURGE OF 
SE SWELL IS EXPECTED TO BEING MOVING ACROSS THE EQUATOR THU. SE 
TO S WINDS ARE EXPECTED TO INCREASE TO 20 KT WED AND THU IN S 
CENTRAL WATERS. THIS WILL ALSO HELP KEEP SEAS ABOVE 8 FT IN MUCH 
OF THE REGION S OF 10N.

$$
SCHAUER