000
AXPZ20 KNHC 210315
TWDEP 

TROPICAL WEATHER DISCUSSION          
NWS NATIONAL HURRICANE CENTER MIAMI FL      
0405 UTC SUN APR 21 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 
0300 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...    
MONSOON TROUGH AXIS FROM 10N85W TO 06N106W THEN ITCZ TO 08N128W.
ITCZ RESUMES FROM 06N133W TO 05N140W. SCATTERED MODERATE 
CONVECTION WITHIN 180 NM OF AXIS E OF 103W AND WITHIN 120W S OF
128W.

...DISCUSSION...
WELL DEFINED CYCLONE AT 29N142W STILL UNABLE TO BREAK E DUE TO 
LARGE OMEGA BLOCK ANCHORED BY ANTICYCLONE 14N107W. WEAKENING
TROUGH ON E SIDE OF BLOCK BREAKS STALEMATE AND ALLOWS CYCLONE TO
SKIRT OVER RIDGE CREST DRAGGING ATTENDANT UPPER LEVEL TROUGH 
ACROSS BASIN N OF 10N AND FORCING ANTICYCLONE EASTWARD. GFS 
GUIDANCE WEAKENS RIDGE AND PLACES IT ALONG 100W BY END OF WEEK...
ALLOWING SEVERAL SHORT WAVES TO MOVE ACROSS NORTHERN LATITUDES
OF BASIN WITH IMPUNITY WHILE RIDGE ADVECTS PLENTY OF TROPICAL
MOISTURE UNTO THE WEST COAST...A RECIPE FOR WET WEATHER. 

...AT THE LOWER LEVELS...
GULF OF TEHUANTEPEC...GALE FORCE WINDS NOTED IN GULF OF
TEHUANTEPEC EARLIER TODAY HAVE DIMINISHED AND WARNING ALLOWED
TO EXPIRE. FRESH N BREEZE EXPECTED TO REACH 20 KT OR LESS LATE
TONIGHT. LINGERING SWELL WILL DRIFT E WHILE SUBSIDING BELOW 8 FT
LATE MON.

WEAKENING HIGH PRES CENTER...NOW ONLY 1034 MB...AT 28N137W DRIFT
NW BUT RIDGE EXTEND WELL SE TO 15N105W MAINTAINING DRY AND STABLE
AIR MASS ACROSS LARGE PORTION OF BASIN N OF ITCZ/MONSOON TROUGH.
ABUNDANT CONVECTIVE DEBRIS ADVECTED NE UNTO BAJA CALIFORNIA.

INCREASING WINDS N OF AREA ALONG COAST OF CALIFORNIA BOUND TO 
FORCE 8-9 FT N SWELLS INTO EPAC N OF 28N FROM 122W AND 128W SUN. 
 
...OUTLOOK...
WITH COLLAPSE OF OMEGA BLOCK AND ITS EASTWARD SHIFT...GUIDANCE
POINT TO SEVERAL SHORTWAVES INTRUDING ALONG N LATITUDES WHICH
COULD DETERIORATE WEATHER ALONG COASTAL SECTIONS MIDWAY THROUGH 
LATE IN THE WEEK.

$$
WALLY BARNES