000
AXPZ20 KNHC 030352
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC THU JAN 03 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 
0330 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
MONSOON TROUGH FROM 08N78W TO 06N88W TO 10N108W. ITCZ AXIS FROM 
10N117W TO 05N140W. NO SIGNIFICANT CONVECTION.

...DISCUSSION...
BROAD MID TO UPPER LEVEL RIDGE OVER WESTERN HALF OF BASIN ABLE 
TO HOLD ITS POSITION AGAINST PUSH FROM DEEP LAYER TROUGH 
APPROACHING FROM THE W. UPPER LEVEL CYCLONE SUPPORTING TROUGH 
SHIFT NE ALLOWING RIDGE TO STALL TROUGH AND ITS ATTENDANT COLD 
FRONT IN NW CORNER OF BASIN...FROM 32N130W TO 26N140W.  

LARGE AMPLITUDE UPPER LEVEL TROUGH DIGS S FROM SW CONUS INTO E 
PAC TO 13N103W. AREA OF UPPER LEVEL DIVERGENT FLOW E OF TROUGH 
ENHANCING SCATTERED CONVECTION FROM 12N TO 14N BETWEEN 99W AND 
101W...BUT PRESENTLY DECREASING IN COVERAGE AND INTENSITY. 

...ELSEWHERE AT THE LOWER LEVELS... 
HIGH PRES CENTER 1020 MB AT 27N131W IS WEAKENING AND EXPECTED TO 
DISSIPATE THU OR EARLY FRI. COLD FRONT LOSES ITS UPPER LEVEL 
SUPPORT AND STALLS FROM 30N132W TO 26N140W FRI WITH ITS FRESH NW 
WINDS DIMINISHING BELOW 20 KT BUT BRINGING IN LARGE LONG PERIOD 
NW SWELL UP TO 15 FT WHICH WILL SPREAD SE TO REACH EQUATOR W OF 
110W BY LATE FRI. FRESH NE TRADES EXPECTED TO DIMINISH IN AREA 
BY FRI AS HIGH PRES WEAKENS. 

WEAKENING HIGH PRES ALSO LOOSENS PRES GRADIENT ENOUGH TO REDUCE 
AREA OF FRESH NW WINDS OVER GULF OF CALIFORNIA RESTRICTING THEM 
TO N OF 29N BY FRI.

GAP WINDS...
GULF OF TEHUANTEPEC...NEXT GALE EVENT EXPECTED TO START LATE 
TONIGHT REACHING GALE FORCE WINDS BY EARLY FRI THEN PERSIST 
THROUGH WEEKEND.

$$
WALLY BARNES