000
AXPZ20 KNHC 280305
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC WED JUL 28 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 
0215 UTC.

...ITCZ...
AXIS ALONG 11N86W TO 11N100W TO 09N110W TO 11N140W. SCATTERED 
MODERATE TO STRONG N OF 06N TO THE COASTS OF PANAMA AND COSTA 
RICA BETWEEN 78W AND 86W...AND N OF 11N TO THE COASTS OF 
NICARAGUA AND EL SALVADOR BETWEEN 86W AND 90W. SCATTERED 
MODERATE WITHIN 120 NM OF AXIS BETWEEN 102W AND 111W. 

...DISCUSSION...
LARGE AMPLITUDE UPPER LEVEL TROUGH EXTENDS FROM WELL N OF THE 
DISCUSSION AREA THROUGH 32N130W BECOMING SHEARED SW TO 23N140W. 
THIS TROUGH IS SHEARING OUT IN THE FACE OF A BROAD RIDGE WHICH 
EXTENDS FROM AN ANTICYCLONE CENTERED OVER SOUTHERN BAJA 
CALIFORNIA WWD THROUGH 23N125W TO 20N140W AND ANCHORED BY 
ANOTHER ANTICYCLONE WELL W OF THE AREA NEAR THE HAWAIIAN 
ISLANDS. NWP MODEL GUIDANCE REINFORCES THE ANTICYCLONE/RIDGE AND 
FORCES THE TROUGH TO GRADUALLY RETREAT TO THE W AS RIDGE 
EXTENDS/BUILDS WWD. VERY DRY AND STABLE AIR MASS DUE TO MODERATE 
TO STRONG SUBSIDENCE IS NOTED N OF 18N W OF 120W AND N OF 23N 
BETWEEN 115W AND 120W. MID TO UPPER LEVEL MOISTURE IS BEING 
ADVECTED TO THE W BY THE ANTICYCLONE NOTED ABOVE AND EXTENDS WWD 
S OF 18N TO 130W BY QUASI ZONAL EASTERLY FLOW ALOFT. LACK OF LOW 
LEVEL FORCING OUTSIDE OF THE ITCZ IS HINDERING THE DEVELOPMENT 
OF DEEP CONVECTION W OF 110W. WIDELY SCATTERED CONVECTION 
ASSOCIATED WITH A LOW LEVEL TROUGH SOUTH OF THE GULF OF 
TEHUANTEPEC HAS DISSIPATED FOR NOW. 

AT THE SURFACE...
BROAD 1028 MB HIGH PRES CENTER WELL NW OF AREA NEAR 44N142W WITH 
AN ASSOCIATED RIDGE AXIS EXTENDING SE THROUGH 30N138W TO 
20N110W. THIS RIDGE EXTENDS JUST TO THE N OF A WEAK SURFACE 
TROUGH SITUATED TO THE N OF THE ITCZ EXTENDING FROM 18N112W TO 
12N115W. 

MODERATE NW WINDS OF 20 KT HAVE BEGUN TO FUNNEL DOWN ALONG THE W 
COAST OF BAJA CALIFORNIA PENINSULA FROM 24N TO 29N. THESE WINDS 
ARE EXPECTED TO PERSIST THROUGH 48 HOURS WITH THE MOST 
PRONOUNCED WINDS DURING THE PEAK AFTERNOON HEATING.  

FRESH E TO SE WINDS OVER S PAC CONTINUES TO GENERATE SOME LONG 
PERIOD SOUTHERLY CROSS EQUATORIAL SWELL WITH SEAS UP TO 10 FT 
ENCROACHING INTO E PAC WATERS S OF 10N AND E OF 95W. SEAS ARE 
EXPECTED TO PERSIST DURING NEXT 48 HOURS.

$$
COBB