000
AXPZ20 KNHC 110235
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC SAT SEP 11 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 
0315 UTC.

...ITCZ...

AXIS CENTERED ALONG 8N79W 8N90W 12N100W 9N110W 12N120W 12N130W
10N140W. SCATTERED MODERATE CONVECTION IS WITHIN 90 NM S OF THE
AXIS BETWEEN 124W-132W...AND ALSO 60 NM S OF THE AXIS BETWEEN
98W-100W.

...DISCUSSION...

A RATHER SHARP NEGATIVELY TILTED UPPER LEVEL TROUGH ENTERS NW 
CORNER OF THE DISCUSSION AREA NEAR 32N131W AND CONTINUES SSE TO 
A CYCLONIC CIRCULATION NEAR 17N129W. THE TROUGH IS SITUATED 
BETWEEN TWO ANTICYCLONES AND RIDGE AXES. THE FIRST ANTICYCLONE 
IS JUST W OF THE DISCUSSION AREA WITH A MEAN CENTER NEAR 19N144W 
...AND WITH AN ASSOCIATED RIDGE EXTENDING EWD TO NEAR 18N132W. 
THE OTHER AND MORE EXTENSIVE ANTICYCLONE IS LOCATED WELL TO THE 
E OF THE REGION OVER FAR EASTERN TEXAS WITH A RIDGE EXTENDING 
W ACROSS NORTHERN MEXICO...THEN TO NW OF THE AREA AT 32N129W.
THE UPPER LEVEL CYCLONE IS LIKELY TO REMAIN TRAPPED IN PLACE OR 
DRIFT TO THE SW WHILE THE PARENT TROUGH SHIFTS NORTHEASTWARD 
AND DAMPENS OUT OVER THE WESTERN U.S. BY SUN NIGHT.

WATER VAPOR IMAGERY CONTINUES TO REVEAL AMPLE MODERATE SUBSIDENCE
COVERING THE AREA W OF A LINE FROM NORTHERN BAJA CALIFORNIA TO
20N125W TO 10N140W. THIS IS MAINTAINING A VERY STABLE ENVIRONMENT
MARKED BY SCATTERED TO BROKEN STRATOCUMULUS CLOUDS MOVING SW TO 
THE N OF OF ABOUT 20N AND W OF 124W.

UPPER LEVEL MOISTURE ORIGINATING FROM THE DEEP TROPICAL CENTRAL
PACIFIC IS TRYING TO INTRUDE INTO THE NW CORNER OF THE REGION AS
IT RIDES UP AND OVER THE CREST OF THE ANTICYCLONE W OF THE 
AREA...BUT IS EVAPORATED ONCE IT REACHES 138W.

MODERATE UPPER LEVEL EASTERLY FLOW AT THE SOUTHERN PERIPHERY OF 
THE MEXICAN RIDGE IS 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 HAMPERING ANY CONVECTION THAT DOES DEVELOP FROM 
ACHIEVING ANY SIGNIFICANT DEPTH IN HEIGHT...EVEN ALONG THE
SUMMERTIME MONSOONAL TROUGH.

AT THE SURFACE...HIGH PRES CENTER 1025 MB WELL NW OF BASIN NEAR 
43N141W HAS AN ASSOCIATED RIDGE EXTENDING SE THROUGH 32N133W TO 
NEAR 24N121W. HIGH PRES COVERS THE AREA N OF 21N W OF 121W.
A WEAK QUASI-STATIONARY 1012 MB LOW IS 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. THE COMBINATION OF WEAK HIGH PRES 
AND LACK OF PERSISTENT LOW PRES IN TROPICAL REGION CONTINUE TO 
ALLOW FOR RELATIVELY LIGHT CONDITIONS THROUGH THE NEXT 48 
HRS.

$$
AGUIRRE