000
AXPZ20 KNHC 010232
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0215 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 ACROSS CENTRAL COSTA 
RICA...TO THE PACIFIC COAST OF COSTA RICA AT 10N85W...THEN 
CONTINUES NW ALONG THE PACIFIC COAST OF CENTRAL AMERICA TO 
17N96W...THEN TURNS SW INTO AN EMBEDDED 1008 MB LOW PRES NEAR
11N103W...THEN NW TO 12N111W...THEN WSW TO 11N125W WHERE 
SCATTEROMETER DATA INDICATES A TRANSITION TO AN ITCZ AXIS 
WHICH CONTINUES W TO BEYOND 09N140W. SCATTERED MODERATE 
ISOLATED STRONG CONVECTION IS NOTED S OF THE MONSOON TROUGH
WITHIN 120 NM OF 06N82W. SIMILAR CONVECTION IS NOTED NW OF
THE EMBEDDED SURFACE LOW WITHIN 60 NM EITHER SIDE OF A LINE 
OF LINE FROM 15N102W TO 11N106W...AND S OF THE MONSOON TROUGH
WITHIN 60 NM EITHER SIDE OF A LINE FROM 11N111W TO 09N117W...
AND ALONG THE ITCZ WITHIN 60 NM EITHER SIDE OF A LINE FROM
09N131W TO 08N140W. 
 
...DISCUSSION...

A UPPER TROUGH...ACCOMPANIED BY A 90 NM WIDE BAND OF MOISTURE... 
IS OVER THE NW PORTION OF THE DISCUSSION AREA FROM 32N127W TO 
30N135W TO BEYOND 31N140W AND WILL SOON MERGE WITH ANOTHER UPPER 
TROUGH WEAKENING FROM 31N126W TO 26N128W. AN UPPER ANTICYCLONE 
IS CENTERED AT 25N117 WITH AN UPPER RIDGE EXTENDING E ACROSS 
NORTHERN OLD MEXICO TO A SHARP CREST AT 24.5105W. AN UPPER RIDGE 
ALSO EXTENDS W FROM THE ANTICYCLONE TO BEYOND 20N140W. THESE 
UPPER FEATURES COMBINE TO DRY OUT THE UPPER LEVELS OF THE 
DISCUSSION AREA ELSEWHERE TO THE W OF A LINE EXTENDING FROM 
30N94W TO 17N140W. 
 
AN UPPER CYCLONE IS NOTED OVER THE DEEP TROPICS AT 05N133W. AN 
AREA OF UPPER DIFFLUENCE IS NOTED N OF THIS CYCLONE AND SW OF 
THE UPPER RIDGE PREVIOUSLY DESCRIBED...ROUGHLY OVER THE LOWER 
LEVEL ITCZ WHERE CONVECTION HAS BURST BETWEEN 131-145W.   
 
AN UPPER TROUGH EXTENDS SW ACROSS THE NW CARIBBEAN AND ACROSS 
CENTRAL AMERICA THROUGH 17N90W TO AN UPPER CYCLONE OVER THE 
TROPICAL PACIFIC AT 15N107.5W...THEN CONTINUES S TO ANOTHER UPPER 
CYCLONE NEAR 04N105W. A 1008 MB SURFACE LOW IS CENTERED NEAR 
17N112W AND IS MOVING SW WHILE WEAKENING. A 1010 MB SURFACE LOW
IS NEAR 12N102W. AN UPPER ANTICYCLONE IS NOTED OVER THE 
CARIBBEAN NEAR 15N75W WITH AN UPPER RIDGE EXTENDING W TO NEAR 
11N107W. 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 13N W OF 112W. 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 32N117W TO 23N140W. 
THESE NW SWELLS...IN THE FORM OF COMBINED SEAS SUBSIDED TO 6-9
FT...WILL ARRIVE ALONG THE PACIFIC COAST OF THE BAJA CALIFORNIA
PENINSULA LATE TONIGHT...CONTINUING TO PROPAGATE SSE COVERING
MOST OF THE DISCUSSION WATERS N OF 10N W OF 112W AROUND MIDDAY
WED. 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.  
 
$$
NELSON