000
AXPZ20 KNHC 212153
TWDEP 

TROPICAL WEATHER DISCUSSION                                     
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
2205 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...              
MONSOON TROUGH 05N77W TO 11N95W TO 10N102W THEN ITCZ TO 05N122W
TO 06N135W TO 05N140W.  SCATTERED MODERATE WITHIN 210 NM S AND
90 NM N OF AXIS. 

...DISCUSSION...     
UPPER LEVEL CYCLONE NOW AT 30N140W MOVING AROUND DOWNSTREAM 
RIDGE CREST HAS NEGATIVELY TILTED TROUGH INCH TO 06N120W.  VERY
DRY AIR MASS DUE TO STRONG SUBSIDENCE FOLLOW W OF TROUGH AXIS N
OF 08N.  SWATH OF CONVECTIVE MOISTURE DEBRIS ADVECTING N ON 45 KT
JET CORE AROUND RIDGE IS CUT OFF BY DRY AIR INTRUSION BY TROUGH
AXIS.  MODERATE DIVERGENCE ALOFT NEAR 05N117W PROMPTS SCATTERED
CONVECTION ENHANCED BY ITCZ UPLIFTING AT THE LOWER LEVELS.

UPPER LEVEL ANTICYCLONE FORCED E BY NEGATIVELY TILTED TROUGH NOW
CENTERED AT 15N100W MAINTAINS LARGE DRY STABLE AIR MASS ACROSS
BASIN FROM 12N TO 22N E OF TROUGH AXIS.

...AT THE LOWER LEVELS...
ABUNDANT MOISTURE FROM SOUTH AMERICA MOVING INTO EPAC JUST S OF
MONSOON TROUGH/ITCZ WITH SCATTERED CONVECTION EXTEND ACROSS 
ENTIRE BASIN.

WEAKENING HIGH PRES CENTER 1031 MB AT 40N136W HAS RIDGE TO 
15N115W WITH GENTLE TO MODERATE BREEZE ACROSS ENTIRE BASIN.
SUBSIDING SWELL TO 9 FT LINGER FROM PREVIOUS GULF OF TEHUANTEPEC
GALE EVENT EXPECTED TO DECAY BELOW 8 FT MON. 

$$
WALLY BARNES