000
AXPZ20 KNHC 062119
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC THU SEP 06 2012

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS 
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1930 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

THE MONSOON TROUGH AXIS WAS ANALYZED FROM 08N78W TO 11N90W TO 
10N98W TO 12N107W TO 08N121W. ITCZ AXIS WAS ANALYZED FROM 
05N125W TO 04N130W TO 08N140W. SCATTERED MODERATE CONVECTION WAS 
WITHIN 90 NM N AND 60 NM S OF THE AXIS BETWEEN 89W AND 94W... 
WITHIN 210 N AND 60 NM S OF THE AXIS BETWEEN 102W AND 
108W....AND WITHIN 75 NM N AND 180 NM S OF THE AXIS BETWEEN 110W 
AND 123W.

...DISCUSSION...

THE UPPER LEVELS FEATURE A BROAD TROUGH CLIPPING THE NW CORNER 
OF THE FORECAST AREA WITH A RIDGE EXTENDING TO ITS S FROM NEAR 
TIJUANA MEXICO TO A COL NEAR 20N134W. DRY AIR ALOFT AN IMPLIED 
SUBSIDENCE DOMINATES THE REGION W OF 130W ACCORDING TO THE WATER 
VAPOR IMAGERY. AN UPPER LOW OVER CENTRAL MEXICO NEAR 25N102W 
EXTENDS A TROUGH AXIS WESTWARD TO 20N120W AND THEN SOUTH TO 
10N128W. CONFLUENCE ALOFT ALONG THIS TROUGH AXIS IS LIMITING 
DEEP CONVECTION OVER THE SOUTHERN GULF OF CALIFORNIA AS WELL AS 
ALONG THE ITCZ AXIS AROUND 130W. AN ANTICYCLONE OVER MEXICO NEAR 
19N98W SPROUTS RIDGE AXES NORTHWARD TO CABO CORRIENTES MEXICO 
AND SOUTHWARD TO THE GULF OF FONSECA AS WELL AS SOUTHWESTWARD TO 
06N125W. UPPER LEVEL DIFFLUENCE ALONG THE RIDGE AXIS THAT 
EXTENDS SOUTHWESTWARD FROM THE ANTICYCLONE IS HELPING TO LIFT 
THE MOISTURE RICH AIR POOLED ALONG THE MONSOON TROUGH W OF 102W. 
THE RESULTING CONVECTION ALONG THE MONSOON TROUGH IS DESCRIBED 
IN THE SECTION ABOVE. 

AT THE SURFACE...THE REMNANTS OF ILEANA AND JOHN ARE STILL 
ANALYZED AS LOW PRES SYSTEMS AT 17N133W AND 26N122W... 
RESPECTIVELY. NEITHER SYSTEM HAS DEEP CONVECTION ASSOCIATED WITH 
IT. WINDS AND SEAS WILL REMAIN BELOW ADVISORY CRITERIA WITH 
THESE REMNANT LOWS. THE 1034 MB SUBTROPICAL HIGH IS ANCHORED 
WELL N OF THE AREA NEAR 45N144W. THE TRADE WINDS REMAIN ONLY AS 
STRONG AS A MODERATE BREEZE DUE TO THE WEAKENED SUBTROPICAL 
RIDGING OVER THE REGION. A WEAK SURFACE TROUGH IS REFLECTED BY 
THE AFOREMENTIONED TROUGH ALOFT STEMMING FROM AN UPPER LOW IN 
CENTRAL MEXICO. THIS SURFACE TROUGH LIES FROM 11N121W TO 05N124W 
AND SEPARATES THE ITCZ FROM THE MONSOON TROUGH. THE PRES 
GRADIENT BETWEEN THIS TROUGH AS WELL AS ALONG WITH THE MONSOON 
TROUGH AND HIGH PRES OVER THE S PACIFIC IS GENERATING FRESH S-SW 
WINDS PRIMARILY IN THE REGION S OF 08N BETWEEN 110W AND 125W 
ACCORDING TO THE 1748 UTC ASCAT AND 1352 UTC WINDSAT PASSES. 
THIS TROUGH IS FORECAST TO WEAKEN AS IT MOVES W OVER THE NEXT 
FEW DAYS.

$$
SCHAUER