000
AXPZ20 KNHC 100311
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC MON SEP 10 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 
0100 UTC.

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

THE MONSOON TROUGH AXIS WAS ANALYZED FROM 08N78W TO 12N94W TO 
11N101W TO 12N109W TO 10N117W TO 11N121W TO 10N127W. THE ITCZ 
AXIS WAS ANALYZED FROM 10N127W TO 10N140W. SCATTERED MODERATE 
CONVECTION WAS WITHIN 150 NM S OF THE AXIS BETWEEN 97W AND 110W 
AS WELL AS WITHIN 90W NM N OF THE AXIS W OF 127W AND FROM 90 NM 
TO 240 NM S OF THE AXIS W OF 133W.

...DISCUSSION...

A MID TO UPPER LEVEL LOW LIES OVER THE NORTHERN GULF OF 
CALIFORNIA. SOUTHERLY FLOW ON THE EASTERN SIDE OF THIS LOW IS 
PUMPING MOISTURE NORTHWARD ALONG THE W COAST OF MEXICO INTO THE 
GULF. SCATTERED MODERATE CONVECTION WAS OVER THE GULF OF 
CALIFORNIA N OF 30N. THIS LOW WILL BE SLOW TO MOVE NORTHEASTWARD 
OUT OF THE AREA.

AN UPPER LEVEL ANTICYCLONE NEAR 22N105W EXTENDS RIDGE AXES 
SOUTHWESTWARD TO TO NEAR 15N140W AND SOUTHEASTWARD ALONG THE 
MEXICAN COAST TO THE GULF OF TEHUANTEPEC. SCATTERED MODERATE WITH
ISOLATED STRONG CONVECTION WITHIN 60 NM OF THE MEXICAN COAST 
BETWEEN 90W AND 101W IS BEING ENHANCED BY DIFFLUENCE ASSOCIATED 
WITH THIS RIDGING ALOFT. A 25-35 KT EASTERLY JET LIES S OF 
THE UPPER RIDGE GENERALLY IN THE AREA BOUNDED FROM 01N TO 07N 
BETWEEN 105W AND 130W. THIS SHEAR IS INHIBITING THE DEVELOPMENT 
OF DEEP CONVECTION...BUT A BROAD AREA OF DIFFLUENCE ALOFT NE OF 
THIS JET IS ENHANCING THE SCATTERED MODERATE CONVECTION ALONG 
THE MONSOON TROUGH DESCRIBED IN THE SECTION ABOVE. AN UPPER LOW 
TROUGH LIES W OF THE AREA ALONG 147W FROM 06N TO 16N. 

THE 1029 MB SUBTROPICAL HIGH WAS ANALYZED NEAR 37N153W. THE HIGH 
IS FORECAST TO MOVE EASTWARD OVER THE NEXT FEW DAYS. THE 2126 
UTC 0SCAT PASS SHOWED FRESH TO STRONG TRADE WINDS HAVE BUILT 
OVER FAR W WATERS WHERE THE PRES GRADIENT IS STRONGEST ALONG THE 
ITCZ E OF THE WEAK SURFACE REFLECTION OF THE AFOREMENTIONED 
UPPER TROUGH ALONG 147W. WINDS AND SEAS HERE SHOULD DIMINISH 
BELOW ADVISORY CRITERIA BY MON NIGHT AS THE TROUGH CONTINUES TO 
MOVE W. 

THE 1946 UTC OSCAT PASS SHOWED A REGION OF FRESH TO STRONG S-SW 
WINDS S OF THE MONSOON TROUGH TO 05N BETWEEN 105W AND 
118W...FORCED BY THE PRES GRADIENT BETWEEN THE MONSOON TROUGH 
AND STRONG HIGH PRES OVER THE SOUTH PACIFIC. THESE WINDS ARE 
EXPECTED TO DIMINISH BELOW ADVISORY CRITERIA AS THE HIGH PRES TO 
THE S WEAKENS OVERNIGHT. S SWELL TO 8 FT CURRENTLY IN THIS 
REGION OF FRESH TO STRONG WINDS WILL SHIFT NORTHEASTWARD OVER 
THE NEXT FEW DAYS TOWARD THE MEXICAN COAST. AT THE SAME 
TIME...THE NUMERICAL GUIDANCE AGREES ON DEVELOPING A BROAD AREA 
OF LOW PRES SW OF THE GULF OF TEHUANTEPEC BY MON AFTERNOON AND 
INCREASING WINDS TO FRESH TO STRONG ON ITS NORTHERN SIDE BETWEEN 
THE MEXICAN COAST AND 12N WHERE THE SW SWELL WILL HAVE ALREADY 
BUILT THE SEAS ABOVE ADVISORY CRITERIA. THIS LOW IS FORECAST TO 
STRENGTHEN AS IT MOVES NW AROUND 10 KT THROUGH TUE EVENING AND 
HAS THE POTENTIAL TO BECOME A TROPICAL CYCLONE DURING THAT TIME.

$$
SCHAUER