000
AXPZ20 KNHC 200239
TWDEP 

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

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

MONSOON TROUGH AXIS EXTENDS FROM 11N86W TO 05N90W. ITCZ AXIS 
CONTINUES FROM 05N90W TO 06N105W TO 03N125W TO 02N140W. A 
CLUSTER OF MODERATE TO ISOLATED STRONG CONVECTION IS WITHIN 45 
NM OF 05N90W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS 
WITHIN 90 NM S OF AXIS BETWEEN 112W AND 118W...AND WITHIN 75 NM 
EITHER SIDE OF AXIS BETWEEN 125W AND 130W. 

...DISCUSSION... 

THE NE PACIFIC IS RELATIVELY QUIET WITH NO GALES...NO GAP WIND 
EVENTS AND NO STRONG FRONTS. SEAS ARE GENERALLY UNDER 8 FT 
ACROSS MUCH OF THE FORECAST WATERS. SEAS OF 8 FT CAN ONLY BE 
FOUND FROM 04N TO 12N BETWEEN 114W AND 125W DUE TO PRIMARILY A 
SW SWELL COMPONENT. 

A 1021 MB HIGH PRES CENTERED NEAR 30N126W EXTENDS A RIDGE SE 
ACROSS THE FORECAST REGION TO NEAR 19N110W. A LIGHT TO GENTLE 
BREEZE IS NOTED OVER THE N-CENTRAL WATERS UNDER THE INFLUENCE OF 
THIS SYSTEM. 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 ACROSS THE CENTRAL AND WESTERN PORTIONS OF 
THE DISCUSSION AREA. SCATTEROMETER DATA CONFIRMED THE PRESENCE 
OF THESE WIND SPEEDS. THE AFOREMENTIONED AREA OF SWELLS AND NE 
15-20 KT TRADE WINDS IS FORECAST TO MOVE WWD OVER THE NEXT 48 
HRS AS THE HIGH PRES CENTER SHIFTS SW. THIS FEATURE WILL BE 
REPLACED BY A BIT STRONGER HIGH PRES LATE WED INTO THU...WITH A  
NEW RIDGE BUILDING IN AND MAINLY DOMINATING THE WATERS N OF 10N 
W OF 115W BY THU. EXPECT AN INCREASE IN WINDS AND SEAS ACROSS 
THE NE WATERS...PARTICULARLY N OF 29N AND E OF 125W BY THU 
EVENING AS PRES GRADIENT TIGHTENS BETWEEN THE HIGH AND LOWER 
PRES OVER THE SW CONUS AND NW MEXICO.
 
A COLD FRONT HAS REACHED THE FAR NW CORNER OF THE AREA AND 
CURRENTLY EXTENDS FROM 30N137W TO 27N140W. THE FRONT IS FORECAST 
TO DISSIPATE OVER THE NW WATERS BY WED AS IT CONTINUES TO MOVE 
SE. WINDS OF 20 KT OR LESS AND SEAS TO AROUND 8 FT ARE NOTED IN 
THE WAKE OF THE FRONT.

ALOFT...A RIDGE/TROUGH/RIDGE PATTERN DOMINATES THE FORECAST 
AREA. AN UPPER LEVEL TROUGH EXTENDS FROM NE MEXICO TO A 
DEVELOPING UPPER LOW AT 15N116W THEN CONTINUES SE TO NEAR 
02N105W. TO THE W OF THE TROUGH...HIGHLY AMPLIFIED UPPER RIDGING 
DOMINATES THE WEST PORTION OF THE FORECAST AREA. THE TROUGH IS 
FORECAST TO LIFT NE THROUGH THU LEAVING BEHIND THE UPPER LOW... 
WHICH WILL MOVE ESE. ANOTHER RIDGE IS NOTED E OF 100W COVERING 
SE MEXICO AND CENTRAL AMERICA.  

$$
GR