000
AXPZ20 KNHC 011603
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC TUE OCT 01 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 ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1545 UTC.

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

THE MONSOON TROUGH AXIS EXTENDS W ACROSS THE SW CARIBBEAN ALONG 
09N FROM THE NW COAST OF COLOMBIA TO NORTHERN COSTA RICA...TO 
THE PACIFIC COAST OF COSTA RICA AT 11N86W...AND CONTINUES TO 
13N96W TO AN EMBEDDED 1010 MB LOW PRES NEAR 12N106W...THEN NW TO 
12N120W...WHERE SCATTEROMETER DATA INDICATES A TRANSITION TO AN 
ITCZ AXIS WHICH CONTINUES TO 09.5N129W TO BEYOND 09N140W. 
SCATTERED MODERATE CONVECTION IS WITHIN 60 NM S OF THE TROUGH 
BETWEEN 122W-124W...AND ALSO WITHIN 45 NM OF THE ITCZ BETWEEN 
134W-137W. 

...DISCUSSION...

BROAD UPPER TROUGHING IS PRESENT OVER THE FAR NW PORTION OF THE 
AREA NW OF A LINE FROM 32N122W TO 26N130W TO 27N140W. A MORE 
ROBUST TROUGH IS NW OF THE AREA CROSSING 34N140W. A WEAKENING 
COLD FRONT ASSOCIATED WITH THE FIRST TROUGH IS JUST N OF THE 
AREA ALONG 33N BETWEEN 127W AND 140W. ISOLATED SHOWERS ARE 
POSSIBLE WITHIN 60 NM OF THE FRONT. AN UPPER ANTICYCLONE IS 
CENTERED AT 25N117 WITH AN UPPER RIDGE EXTENDING ENE ACROSS 
NORTHERN OLD MEXICO TO A SHARP CREST AT 25N106W. AN UPPER RIDGE 
ALSO EXTENDS W FROM THE ANTICYCLONE TO NEAR 20N132W. THESE UPPER 
FEATURES ARE DRY OUT THE UPPER ATMOSPHERE NW AND N OF A LINE 
FROM 24N106W TO 17N126W TO 14N140W.
 
UPPER LEVEL CYCLONIC FLOW IS NOTED S OF 11N W OF 110W WITH A 
RELATED SMALL CYCLONE AT 05N115W. AN AREA OF UPPER DIFFLUENCE N 
OF THE CYCLONIC FLOW AND SW OF THE UPPER RIDGE PREVIOUSLY 
DESCRIBED IS OVER THE MONSOON TROUGH AND ITCZ CONVECTION 
DESCRIBED ABOVE.   
 
AN UPPER TROUGH EXTENDS SW ACROSS THE NW CARIBBEAN AND ACROSS 
CENTRAL AMERICA THROUGH 17N90W...AND SW TO AN UPPER CYCLONE OVER 
THE TROPICAL PACIFIC NEAR 13N116W. A 1010 MB SURFACE LOW IS 
CENTERED NEAR 17N113W AND IS MOVING WSW.  A 1010 MB SURFACE LOW 
IS NEAR 12N106W. AN UPPER ANTICYCLONE IS NOTED OVER THE 
CARIBBEAN NEAR 17N77W WITH AN UPPER RIDGE EXTENDING WSW TO NEAR 
12N106W. THE TWO UPPER FEATURES COMBINE TO SET UP FAVORABLE 
CONDITIONS FOR THE CONVECTION ALONG THE EASTERN PORTION OF THE 
MONSOON TROUGH AND THE SURFACE LOWS. 

ELSEWHERE AT THE SURFACE...A BROAD RIDGE COVERS THE DISCUSSION 
AREA N OF 14N W OF 120W. LONG PERIOD NW SWELLS HAVE PROPAGATED S 
INTO THE NW PORTION OF THE DISCUSSION AREA WITH COMBINED SEA 
HEIGHTS OF 8-12 FT TO THE NW OF A LINE FROM 32N167W TO 21N125W 
TO 19N140W.  THESE NW SWELLS...IN THE FORM OF COMBINED SEAS 
SUBSIDED TO 6-9 FT ARE EXPECTED TO PROPAGATE SSE COVERING MOST 
OF THE DISCUSSION WATERS N OF 10N W OF 112W BY WED AFTERNOON. 
THE SWELLS WILL THEN GRADUALLY SUBSIDE FROM W TO E BEGINNING ON 
THU WITH SEAS BELOW 8 FT ACROSS THE DISCUSSION AREA AROUND 
MIDDAY SAT.  
 
$$
AGUIRRE