000
AXPZ20 KNHC 120922
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC THU SEP 12 2013

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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0900 UTC.

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

THE MONSOON TROUGH AXIS EXTENDS FROM 14.5N96W TO LOW PRES NEAR 
11N123W TO 10N136W. THE ITCZ AXIS EXTENDS FROM 10N136W TO 
10N140W. NUMEROUS MODERATE AND SCATTERED STRONG CONVECTION IS  
WITHIN 270 NM N OF A LINE FROM 13N96W TO 10N104W. SCATTERED 
MODERATE CONVECTION IS WITHIN 120 NM OF THE COAST OF CENTRAL 
AMERICA AND MEXICO BETWEEN 86W AND 96W. ADDITIONALLY... 
SCATTERED MODERATE CONVECTION IS FROM 19N TO 23N E OF 107W.

...DISCUSSION...

AN UPPER LEVEL TROUGH IS SLOWLY ENTERING THE NW CORNER OF THE 
AREA REACHING FROM 32N140W BACK TO THE SW OF THE WATERS. THIS 
UPPER TROUGH IS SUPPORTING A SURFACE COLD FRONT. THIS FRONT IS 
FORECAST TO WEAKEN AS IT VERY SLOWLY REACHES FROM 32N133W TO 
28N140W BY LATE FRI NIGHT WHERE IT WILL LIKELY STALL OUT AND 
DISSIPATE. ONLY MODERATE NORTHERLY WINDS AND 5 TO 7 FT SEAS ARE 
FORECAST BEHIND THE FRONT OVER THE FAR NW PORTION. ANOTHER UPPER 
LEVEL TROUGH IS TO THE E EXTENDING FROM AN UPPER LOW MOVING INTO 
CALIFORNIA. ISOLATED TO SCATTERED SHOWERS ARE OCCURRING N OF 29N 
E OF 124W BEHIND THIS TROUGH/LOW. 

ELSEWHERE ALOFT...AN ANTICYCLONE IS AT 19N131W WITH ANOTHER 
ANTICYCLONE TO THE E AT 19N119W. MAINLY DRY AND STABLE AIR 
COVERS THE MAJORITY OF THE WATERS W OF A LINE FROM THE SOUTHERN 
TIP OF THE BAJA CALIFORNIA PENINSULA TO 20N116W TO 00N120W. A 
LARGER UPPER ANTICYCLONE IS OVER MEXICO AT 25N107W WITH 
CONVECTIVE DEBRIS ADVECTING INTO THE NE PACIFIC WATERS SE OF
THE SAME LINE WHERE PRIMARILY UPPER LEVEL EASTERLIES ARE PRESENT.

1019 MB SURFACE HIGH PRES IS POSITIONED NEAR 27N129W. LIGHT TO 
MODERATE WINDS AND 4 TO 7 FT SEAS ARE N OF 20N W OF 110W. THIS 
HIGH IS FORECAST TO BECOME DIFFUSE THIS WEEKEND WITH NEW HIGH 
PRES BUILDING IN BEHIND THE ABOVE MENTIONED COLD FRONT BY THE 
END OF THE WEEKEND INTO EARLY NEXT WEEK. 

NEARLY STATIONARY 1012 MB SURFACE LOW PRES IS NEAR 15N134W WITH 
AN ATTENDANT SURFACE TROUGH ALONG 134W N OF THE MONSOON TROUGH. 
THIS LOW IS FORECAST TO REMAIN NEARLY STATIONARY THROUGH THE 
NEXT FEW DAYS WITH LIGHT TO MODERATE WINDS AROUND IT. SCATTERED 
SHOWERS ARE OCCURRING IN THE VICINITY OF THE LOW/TROUGH. ANOTHER 
SURFACE LOW IS TO THE SE NEAR 12N122W AT 1011 MB EMBEDDED IN THE 
MONSOON TROUGH. THIS LOW IS FORECAST TO DRIFT TO THE E BEFORE 
DISSIPATING DURING THE NEXT 24-48 HOURS WITH LITTLE SENSIBLE 
IMPACTS.

BROAD LOW PRES IS SW OF THE GULF OF TEHUANTEPEC AREA WHERE DEEP 
CONVECTION AS DESCRIBED IN THE SECTION ABOVE IS OCCURRING. SW 
MONSOONAL FLOW OF 20 TO 25 KT IS BUILDING COINCIDENT SEAS TO 8 
TO 9 FT SW OF THE TEHUANTEPEC REGION. THESE CONDITIONS ARE 
FORECAST TO PERSIST THROUGH THE NEXT FEW DAYS BUILDING SEAS TO 
UP TO 12 FT BY LATE FRI NIGHT WITH WINDS POTENTIALLY INCREASING 
TO AT LEAST 30 KT THEREAFTER.

$$
LEWITSKY