000
AXPZ20 KNHC 291541
TWDEP 

TROPICAL WEATHER DISCUSSION                                    
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
1605 UTC MON APR 29 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 
1500 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...           
THE MONSOON TROUGH IS ALONG 05N77W TO 09N88W TO 07N104W TO 
07N110W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 
07N110W TO 10N127W TO 06N134W TO 05N140W. WIDELY SCATTERED 
MODERATE CONVECTION IS FROM 03N TO 07N E OF 79W...AND FROM 05N 
TO 08N BETWEEN 92W AND 96W. SCATTERED MODERATE CONVECTION IS 
FROM 05N TO 08N BETWEEN 101W AND 103W...AND FROM 08N TO 10N 
BETWEEN 109W AND 115W. SCATTERED MODERATE AND ISOLATED STRONG 
CONVECTION IS FROM 03N TO 13N BETWEEN 119W AND 132W.

...DISCUSSION...                                                
WHILE AN UPPER LEVEL BLOCKING PATTERN PERSISTS ACROSS THE 
NORTHERN PACIFIC N OF 35N...WATER VAPOR IMAGERY INDICATES A 
BROAD MIDDLE TO UPPER LEVEL LOW CENTERED NEAR 30N136W CONTINUES 
TO ROTATE AROUND THE SOUTHERN PERIPHERY OF THIS UPPER LEVEL 
HIGH. DRY AIR AND SUBSIDENCE PREVAILS ALOFT N OF 20N UNDER FAIR 
SKIES AND SURFACE RIDGING ANCHORED BY A 1029 MB HIGH CENTERED 
NORTH OF THE DISCUSSION AREA NEAR 40N137W. THIS CONTINUES TO 
KEEP CONDITIONS RELATIVELY QUIET FOR THE NEAR TERM OVER A 
MAJORITY OF THE BASIN N OF 15N W OF 110W. LOOKING AHEAD FOR THIS 
REGION...A WEAK IMPULSE OF MID-LEVEL ENERGY IS EXPECTED TO SLIDE 
SOUTH ALONG THE CALIFORNIA COAST WITH SUSTAINED NORTHERLY WINDS 
RESULTING AND SEAS BUILDING TO 10 FT BY EARLY WEDNESDAY IN THE 
VICINITY OF 30N126W. SEAS ABOVE 8 FT WILL GENERALLY LOCATE N OF 
26N BETWEEN 119W AND 133W IN NORTH SWELL AT THE 48 HOUR MARK.

THE REMAINDER OF THE AREA S OF 20N W OF 110W REMAINS FOCUSED ON 
A SURFACE TROUGH EMBEDDED WITHIN THE ITCZ AXIS ANALYZED FROM 
06N130W TO 12N128W AND DRIFTING WESTWARD. AN OVERALL ENHANCED 
AREA OF NE TO E TRADES EXISTS IN THE VICINITY OF THE TROUGH FROM 
10N TO 14N BETWEEN 123W AND 131W. THIS AREA IS EXPECTED TO 
SHRINK IN SIZE OVER THE NEXT 24 HOURS AS THE TROUGH WEAKENS 
SOMEWHAT THUS RELAXING THE PRESSURE GRADIENT ASSOCIATED WITH THE 
SURFACE RIDGING TO THE NORTH. CONVECTION IN THIS AREA REMAINS 
FAIRLY ACTIVE THIS MORNING COVERING A BROAD AREA FROM 03N TO 13N 
BETWEEN 119W AND 132W...LIKELY SUPPORTED ALOFT BY A FAVORABLE 
MIDDLE TO UPPER LEVEL DIFFLUENT ENVIRONMENT.
 
E OF 110W...RELATIVELY TRANQUIL CONDITIONS ARE NOTED IN 
OBSERVATIONAL DATA...RECENT SCATTEROMETER PASSES...AND LATEST 
GLOBAL MODEL DATA. OF NOTE...STRONG SW SWELL FROM A SOUTHERN 
HEMISPHERE LOW PRESSURE SYSTEM CONTINUES SPREADING NORTHEASTWARD 
REACHING THE MEXICAN AND CENTRAL AMERICAN COAST WITH WAVE 
PERIODS IN THE RANGE OF 15 TO 18 SECONDS. THIS LONG PERIOD SWELL 
EVENT IS EXPECTED TO PERSIST THROUGH LATE THURSDAY.

$$
HUFFMAN