000
AXPZ20 KNHC 070300
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC FRI SEP 07 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0115 UTC.

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

THE MONSOON TROUGH AXIS WAS ANALYZED FROM 08N78W TO 12N88W TO 
10N97W TO 12N107W TO 09N121W. THE ITCZ AXIS WAS ANALYZED FROM 
05N126W TO 04N130W TO 08N140W. SCATTERED MODERATE CONVECTION WAS 
WITHIN 120 NM N AND 180 NM S OF THE AXIS BETWEEN 106W AND 117W. 
A TROUGH LIES BETWEEN THE MONSOON TROUGH AND ITCZ FROM 12N123W 
TO 04N124W. SCATTERED MODERATE CONVECTION WAS WITHIN 270 NM E OF 
THE TROUGH FROM 09N TO 12N.

...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 
SAN DIEGO CALIFORNIA TO A COL NEAR 18N134W. DRY AIR ALOFT AND 
IMPLIED SUBSIDENCE DOMINATES THE REGION W OF 130W ACCORDING TO 
THE WATER VAPOR IMAGERY. AN UPPER TROUGH AXIS SNAKES THROUGH THE 
FORECAST AREA FROM THE SOUTHERN TIP OF BAJA CALIFORNIA THROUGH 
12N135W TO 00N130W. CONFLUENCE ALOFT ALONG THIS TROUGH AXIS IS 
LIMITING DEEP CONVECTION ALONG THE ITCZ AXIS AROUND 130W. AN 
ANTICYCLONE OVER MEXICO NEAR 19N101W SPROUTS RIDGE AXES 
SOUTHEASTWARD TO THE GULF OF FONSECA AS WELL AS SOUTHWESTWARD 
THROUGH MANZANILLO MEXICO TO 08N124W. SCATTERED MODERATE TO 
STRONG CONVECTION WAS NOTED WITHIN 60 NM OF THE COAST FROM 
NICARAGUA TO SOUTHERN MEXICO BETWEEN 86W AND 94W UNDER THE 
SOUTHEASTERN RIDGE AXIS. UPPER LEVEL DIFFLUENCE ALONG THE 
SOUTHWESTERN RIDGE AXIS 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. A 25-35 KT EASTERLY JET OVER MUCH OF THE AREA S OF 10S 
BETWEEN 85W AND 105W IS INHIBITING THE DEVELOPMENT OF DEEP 
CONVECTION THERE.

AT THE SURFACE...THE REMNANTS OF ILEANA HAVE FINALLY OPENED UP 
TO A TROUGH THAT WAS ANALYZED FROM 19N133W TO 15N134W. THE LOW 
LEVEL CIRCULATION ASSOCIATED WITH THE REMAINS OF JOHN CONTINUES 
TO BE ANALYZED AS A 1012 MB LOW PRES SYSTEM NEAR 27N122W. 
NEITHER SYSTEM HAS DEEP CONVECTION ASSOCIATED WITH IT. WINDS AND 
SEAS WILL REMAIN BELOW ADVISORY CRITERIA NEAR BOTH SYSTEMS. THE 
1033 MB SUBTROPICAL HIGH IS ANCHORED WELL N OF THE AREA NEAR 
46N143W. 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 THAT IS GENERALLY CENTERED NEAR 130W S OF 12N. THIS 
SURFACE TROUGH LIES FROM 12N123W TO 04N124W 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 100W AND 125W ACCORDING TO THE 1900 
UTC AND 2038 UTC OSCAT PASSES. THIS TROUGH IS FORECAST TO WEAKEN 
AS IT MOVES W OVER THE NEXT FEW DAYS.

$$
SCHAUER