000
AXPZ20 KNHC 182157
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC THU APR 18 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 10N85W TO 06N107W TO 09N119W.  ITCZ FROM 09N125W
TO 03N140W.  SCATTERED MODERATE TO STRONG CONVECTION WITHIN 240
NM S OF AXIS E OF 103W.

...DISCUSSION... 
UPPER LEVEL CYCLONE REMAINS AT 29N140W UNABLE TO MAKE A DENT IN
LARGE RIDGE WELL ANCHORED BY ANTICYCLONE AT 15N108W.  TROUGH 
EXTEND FROM CYCLONE TO 00N144W WITH VERY DRY STABLE AIR MASS 
ALOFT WITHIN 4 DEG FROM AXIS.  ANTICYCLONE CONTRIBUTES TO AREA
OF MODERATE TO STRONG DIVERGENCE ALOFT RIGHT OVER SURFACE TROUGH
WHICH EXTEND FROM 05N TO 11N ALONG 122W.  SCATTERED MODERATE 
CONVECTION INCREASING WITHIN 120 NM E OF AXIS.  MOIST CONVECTIVE
DEBRIS ADVECTED N AND NE BY ANTICYCLONE TOWARDS CENTRAL MEXICO.

SECOND UPPER LEVEL TROUGH SPLITS LARGE EPAC RIDGE FROM ANOTHER
RIDGE OVER SOUTH AMERICA WHICH IS ADVECTING LARGE AMOUNTS OF 
TROPICAL MOISTURE INTO BASIN ALONG MONSOON TROUGH LATITUDES WITH
SCATTERED MODERATE ISOLATED STRONG CONVECTION S OF MONSOON AXIS
E OF 103W. 

...ELSEWHERE AT THE LOWER LEVELS...
HEALTHY HIGH PRES CENTER 1038 MB AT 37N137W IN PERFECT POSITION
TO PROMPT GALE FORCE WINDS ALONG CALIFORNIA COAST AND FUNNEL NW
FLOW INTO GULF OF CALIFORNIA INCREASING WINDS TO NEAR GALE FORCE.
SEAS EXPECTED TO BUILD TO 9 FT FROM 24N TO 27N.  FRESH NE TRADE
WINDS BUILDS AND PROPAGATES 10 FT SWELLS S OF 15N BY END OF 
FORECAST PERIOD. 

LATE SEASON COLD FRONT ACROSS GULF OF MEXICO FRI FORCE STRONG N 
WINDS ACROSS CHIVELAS PASS BRINGING A BRIEF MOMENT OF GALE FORCE
WINDS TO GULF OF TEHUANTEPEC LATE FRI NIGHT OR EARLY SAT. 

...OUTLOOK...
LARGE OMEGA BLOCK OVER EPAC EXPECTED TO REMAIN IN PLACE WITH 
FEW DISTURBING FEATURES TO PROMOTE DETERIORATING CONDITIONS. 
BASIN SHOULD REMAIN TAME AS PRESENT WINDS ABATE AND SWELLS 
SUBSIDE.  

$$
WALLY BARNES