000
AXPZ20 KNHC 211531
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC WED JUL 21 2010

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

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1245 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE WAS ANALYZED ALONG 13N95W TO 
12N105W TO 11N115W TO 12N126W TO 09N140W. SCATTERED MODERATE 
CONVECTION IS BETWEEN 120 NM AND 180 NM S OF THE ITCZ AXIS E OF 
109W...WITHIN 120 NM N OF THE ITCZ AXIS BETWEEN 122W AND 
125W...AND WITHIN 75 NM N OF THE ITCZ AXIS W OF 139W.

...DISCUSSION...

AN UPPER LEVEL RIDGE ENTERS THE AREA FROM 26N140W TO 30N134W. AN 
UPPER LEVEL LOW IS CENTERED NEAR 30N128W AND EXTENDS A WEAK 
TROUGH SW TO 14N139W WITH MID TO UPPER LEVEL MOISTURE EVIDENT N 
OF 26N BETWEEN 124W AND 133W. THIS UPPER TROUGH IS EXPECTED TO 
SHIFT SLIGHTLY W DURING THE NEXT 48 HOURS...PUSHING THE RIDGE 
AXIS W OF THE AREA. AN UPPER LEVEL HIGH IS POSITIONED NEAR 
20N117W WITH A RIDGE EXTENDING SW TO NEAR 12N136W. AN UPPER 
LEVEL LOW IS JUST NE OF THIS HIGH NEAR 25N114W AND YET ANOTHER 
ANTICYCLONE LIES JUST TO THE E OVER MAINLAND MEXICO NEAR 
23N106W. BROAD UPPER LEVEL DIFFLUENCE IS IN PLACE BETWEEN THIS 
EASTERN ANTICYCLONE AND A 30 TO 50 KT EAST-NORTHEASTERLY JET 
THAT DOMINATES THE REGION S OF 10N BETWEEN 82W AND A LINE FROM 
10N100W TO 00N117W. THIS DIFFLUENCE IS ENHANCING CONVECTION 
ALONG THE COAST OF SOUTHERN MEXICO AND NORTHERN CENTRAL AMERICA 
WITH SCATTERED MODERATE CONVECTION NOTED WITHIN 150 NM OF THE 
COAST BETWEEN 87W AND 97W. OTHERWISE...STRONGER VERTICAL WIND 
SHEAR ASSOCIATED WITH THE AFOREMENTIONED UPPER JET IS INHIBITING 
CONVECTION OVER MUCH OF SE WATERS.

A 1037 MB HIGH PRES AT THE SURFACE IS CENTERED WELL NW OF THE 
DISCUSSION AREA NEAR 46N151W WITH A RIDGE AXIS EXTENDING THROUGH 
30N131W TO 15N116W. THE TROUGH AXIS IS MARKED BY STABLE AIR AND 
STRATOCUMULUS...ESPECIALLY N OF 17N. A WEAK TROUGH...THE 
REMNANTS OF T.D. SIX-E...REMAINS FROM 20N129W TO 15N132W 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 11 FT RANGE OVER
THE DISCUSSION AREA N OF 24N BETWEEN 119W AND 135W. THIS SWELL 
WILL GRADUALLY SUBSIDE TO 8 FT THU NIGHT AND BELOW 8 FT BY FRI 
MORNING.

LONG PERIOD CROSS EQUATORIAL SOUTHERLY SWELL OF 8 TO 9 FT LIES 
ACROSS THE S CENTRAL PORTION OF THE FORECAST AREA GENERALLY S OF 
10N BETWEEN 95W AND 130W. THIS SWELL WILL GRADUALLY DECAY OVER 
THE NEXT TWO DAYS...BUT A NEW SURGE OF SE SWELL IS EXPECTED TO 
MOVE ACROSS THE EQUATOR THU NIGHT. IN ADDITION...SE TO S WINDS 
ARE EXPECTED TO INCREASE TO 20 KT TONIGHT THROUGH FRI IN S 
CENTRAL WATERS. THIS WILL HELP KEEP SEAS ABOVE 8 FT IN MUCH OF 
THE REGION S OF 10N THROUGH FRI MORNING.

$$
SCHAUER