000
AXPZ20 KNHC 102146
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC FRI SEP 10 2010

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

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2145 UTC.

...ITCZ...
AXIS FROM 08N79W TO 09N95W...THEN RESUMES AT 11N100W AND 
CONTINUES TO 09N107W TO 12N118W TO 12N130W TO 10N140W. SCATTERED 
MODERATE WITHIN 60 NM S OF AXIS BETWEEN 90W AND 95W...97W AND 
102W AND 120 NM S OF AXIS BETWEEN 120W AND 135W.

...DISCUSSION...
RATHER SHARP NEGATIVELY TILTED UPPER LEVEL TROUGH ENTERS NW 
CORNER OF THE DISCUSSION AREA NEAR 32N131W AND CONTINUES SSE TO 
A CYCLONIC CIRCULATION NEAR 16N129W. THIS NARROW TROUGH IS 
SITUATED BETWEEN TWO ANTICYCLONES AND RIDGE AXES. THE FIRST 
ANTICYCLONE IS CENTERED JUST W OF THE DISCUSSION AREA WITH A 
MEAN CENTER NEAR 19N144W WITH A RIDGE EXTENDING EWD TO NEAR 
20N131W. THE OTHER AND MORE EXTENSIVE ANTICYCLONE IS CENTERED 
ALONG THE RIO GRANDE RIVER NEAR 28N100W AND EXTENDS WWD ACROSS 
NORTHERN MEXICO...CENTRAL BAJA CALIFORNIA TO 24N125W. THE UPPER 
LEVEL CYCLONE IS LIKELY TO REMAIN TRAPPED IN PLACE OR DRIFT TO 
THE SW WHILE THE PARENT TROUGH SHIFTS MORE NE AND WEAKENS TO A 
SHEAR AXIS IN BETWEEN THE TWO DOMINANT ANTICYCLONES. 

VERY DRY AND STABLE ATMOSPHERE DUE TO MODERATE TO STRONG  
SUBSIDING AIR MASS COVERS THE AREA W OF A LINE FROM 30N107W TO 
25N123W TO 10N140W...AND S OF THE ITCZ W OF 115W. MODERATE UPPER 
LEVEL EASTERLY FLOW AT THE SOUTHERN PERIPHERY OF THE RIDGE WAS 
ADVECTING ABUNDANT MID AND UPPER LEVEL TROPICAL MOISTURE 
ACROSS BAJA CALIFORNIA AND THE E PACIFIC N OF 20N E OF 120W. 
ABOVE NORMAL VERTICAL SHEAR ACROSS TROPICAL E PACIFIC CURTAILS 
SIGNIFICANT CONVECTION DEVELOPING ALONG SUMMERTIME MONSOONAL 
TROUGH.

AT THE SURFACE...HIGH PRES CENTER 1025 MB WELL NW OF BASIN NEAR 
43N141W HAS AN ASSOCIATED RIDGE EXTENDING SE THROUGH 30N133W TO 
21N115W. A WEAK QUASI-STATIONARY 1012 MB SURFACE LOW WAS NOTED 
ALONG THE ITCZ NEAR 12N135W...HOWEVER STABLE AIR MASS IN PLACE 
AND ADVERSE UPPER ENVIRONMENT IS LIMITING CONVECTIVE ACTIVITY 
AND HENCE DEVELOPMENT OF THE LOW.

$$
COBB