000
AXPZ20 KNHC 200318
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC SAT APR 20 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 09N84W TO 10N91W TO 07N99W TO 07N110W TO 05N116W
THEN ITCZ TO 04N122W TO 06N127W TO 05N140W.  SCATTERED MODERATE
ISOLATED STRONG CONVECTION WITHIN 360 NM S OF AXIS E OF 102W AND
WITHIN 120 NM OF AXIS FROM 102W TO 117W.

...DISCUSSION... 
UPPER LEVEL CYCLONE AT 26N143W UNABLE TO DENT THE MASSIVE OMEGA
BLOCK CENTERED ON WELL DEFINED STATIONARY ANTICYCLONE AT 15N108W.
NEGATIVE-TILTED TROUGH EXTEND FROM CYCLONE TO 03N119W W OF 
ANTICYCLONE WHILE SECOND TROUGH DIGS SW FROM NICARAGUA TO 08N97W.
PLENTY OF TROPICAL MOISTURE...MAINLY CONVECTIVE DEBRIS FROM ITCZ
...ADVECTS N AND NE AROUND RIDGE CREST WITH LITTLE EFFECTS AS 
AIR MASS REMAINS QUITE STABLE.  ON THE E SIDE...SECOND TROUGH 
PROMOTES MODERATE DIVERGENT FLOW ALOFT ENHANCING CONVECTION 
ALONG AND S OF MONSOON TROUGH E OF 102W.  CONVECTION DECREASING
IN LAST FOUR HOURS MAY INDICATE WEAKENING TROUGH AS RIDGE OVER
S AMERICA TRIES TO EXPAND W.

...ELSEWHERE AT THE LOWER LEVELS...
WEAK SURFACE TROUGH FROM 08N-12N ALONG 125W MOVING AWAY FROM 
UNDER AREA OF DIVERGENCE ALOFT AND IS EXPECTED TO FURTHER WEAKEN
AND BECOME DIFFUSE BY SUN.

LATE SEASON COLD FRONT MOVES THROUGH GULF OF MEXICO FUNNELING 
STRONG N WINDS ACROSS CHIVELAS PASS RESULTING IN GALE FORCE 
WINDS INTO GULF OF TEHUANTEPEC TONIGHT AND EARLY SAT THEN 
DIMINISH TO A MODERATE BREEZE BY SUN.

CURRENT REGION OF 8-9 FT N-NE SWELLS IN WESTERN SIDE OF BASIN
EXPECTED TO DECAY BELOW 8 FT LATE SAT NIGHT. 

MOSTLY DRY AND STABLE CONDITIONS ACROSS REMAINING BASIN POINTS
TO MAINLY DIMINISHING WINDS OVER BOTH GULFS OF CALIFORNIA AND 
TEHUANTEPEC WITHIN NEXT 24 HOURS.  SWELL TRAINS INTRUDING INTO
EPAC W OF 120W FROM N AND W OF 95W FROM THE S EXPECTED TO BECOME
THE ONLY FEATURES IN NEXT 24 HOURS.

...OUTLOOK...
WITH LARGE OMEGA BLOCK IN PLACE AND NOT MOVING...ONLY EXPECTED
WEATHER FEATURE WOULD BE CONVECTIVE ACTIVITY ALONG ITCZ/MONSOON
TROUGH ENHANCED BY UPPER LEVEL DIVERGENT FLOW.

$$
WALLY BARNES