000
AXPZ20 KNHC 220312
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC SAT SEP 22 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 
0300 UTC.

...SPECIAL FEATURES...
TROPICAL DEPRESSION THIRTEEN-E 1005 MB 13.7N 107.5W MOVE W OR 
275 DEGREES AT 10 KT EXPECTED TO INTENSIFY TO TROPICAL STORM 
LATE TONIGHT AS IT REACH 13.9N 108.8W EARLY SAT THEN TO 14.9N 
111.8W EARLY SUN.  MAXIMUM WINDS 30 GUST TO 40 KT.  SCATTERED 
MODERATE TO STRONG CONVECTION FROM 10-16N BETWEEN 105W-112W.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
MONSOON TROUGH FROM 08N84W TO 13N89W TO 13N101W THEN RESUME FROM 
13N113W TO 09N129W THEN ITCZ TO 08N137W TO BEYOND 08N140W. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION WITHIN 180 NM S OF 
AXIS E OF 87W AND WITHIN 150 NM S OF AXIS FROM 93W TO 101W.  
SCATTERED MODERATE CONVECTION WITHIN 180 NM S OF AXIS FROM 126W 
TO 131W.
 
...DISCUSSION...
BROAD ANTICYCLONE AT 10N140W FORCED S BY APPROACHING STRONG 
UPPER LEVEL TROUGH CURRENTLY EXTENDING FROM 32N131W TO BEYOND 
28N140W.  ABUNDANT TROPICAL MOISTURE RIDES 75 KT JET CORE AHEAD 
OF TROUGH AXIS.  RIDGE CREST TILTS NE TRAPPED BETWEEN THAT 
TROUGH AND A SECOND ONE ANCHORED BY CYCLONE ALOFT AT 01N124W AND 
A SECOND ONE AT 15N125W.  EASTERNMOST TROUGH THEN EXTEND NE TO 
24N111W.  EXCEPT ABOVE MENTIONED MOISTURE SWATH...MOST OF BASIN 
N OF 11N W OF 117W REMAINS VERY DRY AND STABLE.  DOWNSTREAM... 
ANTICYCLONE AT 13N102W...STACKED ABOVE SURFACE LOW PRES 1005 MB 
AT 14N107W...PROVIDING LIGHT WIND SHEAR ENVIRONMENT AND 
ENHANCING OUTFLOW.  SEE SPECIAL FEATURES ABOVE FOR LOW PRES 
DETAILS.

...ELSEWHERE AT LOWER LEVELS...
SURFACE HIGH PRES CENTER 1026 MB N OF BASIN BRINGS MODERATE TO 
FRESH N BREEZE ACROSS 30N BETWEEN 123W AND 128W BUILDING SEAS TO 
8 FT THROUGH SAT.  WIND AND SEAS SUBSIDE LATE SAT. PRES GRADIENT 
BETWEEN RIDGE AND ITCZ PROMPTS SURGE OF FRESH NE BREEZE W OF 
135W FROM 10N TO 15N EXPECTED TO DIMINISH LATE SAT WITH 8 FT 
SWELL LINGERING THROUGH FORECAST PERIOD. 

SWATH OF STRONG NE WINDS OVER GULF OF TEHUANTEPEC EXPECTED TO 
REMAIN WITH LITTLE CHANGE THROUGH LATE SUN.

$$
WALLY BARNES