000
AXPZ20 KNHC 210241
TWDEP 

TROPICAL WEATHER DISCUSSION                                   
NWS NATIONAL HURRICANE CENTER MIAMI FL                        
0405 UTC THU MAR 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 
0200 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

MONSOON TROUGH EXTENDS ACROSS THE GULF OF PANAMA TO 08N82W THEN 
CONTINUES TO 05N90W TO 04N100W TO 02N110W. ITCZ IS FROM 02N110W 
TO 04N115W TO 02N140W. SCATTERED MODERATE ISOLATED STRONG 
CONVECTION IS NOTED FROM 04N TO 07N BETWEEN 83W AND 89W...AND   
BETWEEN 108W AND 117W. SCATTERED MODERATE CONVECTION IS N OF THE 
ITCZ AXIS TO 05N BETWEEN 125W AND 130W. 

...DISCUSSION... 

NO MUCH OF INTEREST IN THE NE PACIFIC REGION THIS EVENING AS 
THERE ARE NO GALES...NO GAP WIND EVENTS...NO ACTIVE COLD 
FRONTS...AND NO DEEP CONVECTION. THE EXCEPTION WAS A CLUSTER OF 
MODERATE TO STRONG CONVECTION NOTED S OF THE MONSOON TROUGH 
EARLY THIS EVENING. UPPER DIFFLUENCE WAS HELPING TO INDUCE THIS 
CONVECTIVE ACTIVITY THAT HAS DIMINISHED OVER THE LAST FEW HOURS. 

A WEAK RIDGE DOMINATES THE FORECAST WATERS N OF 10N W OF 110W.  
A LIGHT TO GENTLE BREEZE IS NOTED PER THE MOST RECENT 
SCATTEROMETER PASSES N OF 17N. THE WEAKER PRES GRADIENT ON THE 
SOUTHERN PERIPHERY OF THIS RIDGE IS ONLY ALLOWING FOR WEAK NE 
TRADE WINDS OF ABOUT 15-20 KT TO PERSIST BETWEEN THE ITCZ AND 
17N. AN AREA OF MIXED NE AND SW SWELL WITH SEAS TO 8 FT 
CONTINUES TO PROPAGATE WESTWARD INTO THE AREA OF MODERATE TO 
FRESH TRADE WINDS. MARINE GUIDANCE INDICATES THAT SEAS WILL 
SUBSIDE BELOW 8 FT BY LATE THU.

A WEAKENING STATIONARY FRONT STRETCHES FROM 30N131W TO 24N140W 
WITH LITTLE IMPACT. THIS FRONT WILL CONTINUE TO DISSIPATE OVER 
THE FORECAST WATERS OVERNIGHT TONIGHT. HIGH PRES IN THE WAKE OF 
THE FRONT CURRENTLY LOCATED NW OF THE FORECAST AREA WILL MOVE 
EWD WHILE STRENGTHENING. AS A RESULT...THE PRESSURE GRADIENT 
WILL INCREASE OVERNIGHT THU NIGHT OFF THE COAST OF BAJA 
CALIFORNIA BETWEEN THE HIGH AND INCREASED TROUGHING OVER THE 
INTERMOUNTAIN WESTERN U.S. AND NW MEXICO. THIS WILL BRING A 
FRESH TO STRONG N-NW BREEZE TO NE FORECAST WATERS OFF BAJA 
CALIFORNIA NORTE...WITH SEAS BUILDING TO AROUND 12 FT BY FRI 
AFTERNOON.  
 
ANOTHER SET OF NW SWELL SHOULD REACH THE FAR NW PORTION THU 
EVENING AND WILL PROPAGATE SE ACROSS THE NW WATERS BY FRI. THIS 
SWELL EVENT IS FORECAST TO MIX WITH CROSS EQUATORIAL SOUTHERLY 
SWELL AND THE NE WIND WAVES GENERATED BY THE TRADES RESULTING IN 
AN AREA OF SEAS OVER 8 FT W OF A LINE FROM 30N116W TO 23N130W TO 
15N140W. THE HIGHEST SEAS OF 10 TO 13 FT ARE EXPECTED TO IMPACT 
THE WATERS N OF 27N BETWEEN 118W AND 130W.  

$$
GR