000
AXPZ20 KNHC 090250
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC SUN SEP 09 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 
0045 UTC.

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

THE MONSOON TROUGH AXIS WAS ANALYZED FROM 08N78W TO 11N88W TO 
11N104W TO 09N113W TO 11N125W. SCATTERED MODERATE WITH ISOLATED 
STRONG CONVECTION WAS S OF THE AXIS TO 06N BETWEEN 82W AND 92W 
AND N OF THE AXIS TO 13N WITHIN 60 NM OF THE COAST OF COSTA RICA 
AND NICARAGUA. SCATTERED MODERATE WITH ISOLATED STRONG WITHIN 90 
NM N AND 180 NM S OF THE AXIS BETWEEN 98W AND 108W. A SURFACE 
TROUGH LIES JUST W OF THE MONSOON TROUGH. THIS TROUGH WAS 
ANALYZED FROM 12N130W TO 06N138W. SCATTERED MODERATE CONVECTION 
WAS WITHIN 150 NM NW OF THE TROUGH.
  
...DISCUSSION...

AN UPPER LEVEL ANTICYCLONE NEAR 21N115W EXTENDS RIDGE AXES 
SOUTHWESTWARD TO 15N137W AND EASTWARD ACROSS CABO CORRIENTES 
MEXICO TO ANOTHER ANTICYCLONE NEAR 21N99W. MEANWHILE...A MID TO 
UPPER LEVEL LOW LIES OVER BAJA CALIFORNIA NORTE. SOUTHERLY FLOW 
ON THE EASTERN SIDE OF THIS LOW IS PUMPING MOISTURE NORTHWARD 
ALONG THE W COAST OF MEXICO INTO THE GULF OF CALIFORNIA. 
SCATTERED MODERATE CONVECTION WAS IN THE NORTHERN GULF OF 
CALIFORNIA N OF 30N E OF 114W TO THE E OF THE UPPER LOW. 
PRECIPITABLE WATER IMAGERY SHOWS MOSITURE POOLED ALONG THE COAST 
NEAR CABO CORRIENTES MEXICO WHERE THE RIDGE AXIS ALOFT IS ABLE 
TO LIFT THIS MOISTURE AND ENHANCE THE SCATTERED MODERATE TO 
STRONG CONVECTION WAS FOUND FROM 19N TO 21N BETWEEN 105W AND 
107W AND WITHIN 60 NM OF THE MEXICAN COAST FROM 21N TO 23N. A 
30-50 KT EASTERLY JET LIES S OF THE ANTICYCLONE IN THE REGION 
FROM 01N TO 14N BETWEEN 107W AND 125W. THIS SHEAR IS INHIBITING 
THE DEVELOPMENT OF DEEP CONVECTION...BUT A BROAD AREA OF 
DIFFLUENCE ALOFT E OF THIS JET IS ENHANCING THE SCATTERED 
MODERATE WITH ISOLATED STRONG CONVECTION ALONG THE MONSOON 
TROUGH DESCRIBED IN THE SECTION ABOVE. AN UPPER LOW LIES ALONG 
THE EQUATOR SOUTH OF THE JET AND EXTENDS A TROUGH NORTHWESTWARD 
THROUGH 00N130W TO 06N140W. THE SURFACE REFLECTION OF THIS 
TROUGH AND THE CONVECTION ASSOCIATED WITH IT IS ALSO DESCRIBED 
IN THE SECTION ABOVE. 

THE 1028 MB SUBTROPICAL HIGH WAS ANALYZED NEAR 37N151W. THE HIGH 
IS CURRENTLY BEING ENCROACHED UPON BY A FRONT TO ITS NW. THIS 
FRONT IS FORECAST TO MOVE EASTWARD AND USHER IN STRONGER HIGH 
PRES. FRESH TO STRONG TRADE WINDS ARE EXPECTED TO BUILD OVER FAR 
W WATERS JUST N OF THE AFOREMENTIONED SURFACE TROUGH ON SUN AND 
SHOULD DIMINISH BY THE END OF THE PERIOD MON EVENING AS THE 
TROUGH MOVES W OF THE AREA. THE 1524 UTC AND 1704 UTC ASCAT 
PASSES SHOW A REGION OF FRESH TO STRONG S-SW WINDS LIES S OF THE 
MONSOON TROUGH TO 05N BETWEEN 93W AND 110W...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 ON SUN. S 
SWELL TO 8 FT CURRENTLY IN THIS REGION OF FRESH TO STRONG WINDS 
WILL SHIFT NORTHWARD 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 S 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 S 
SWELL WILL HAVE ALREADY BUILT THE SEAS TO 8 FT.

$$
SCHAUER