000
AXPZ20 KNHC 211502
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL 
1605 UTC SAT DEC 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.
 
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 

THE MONSOON TROUGH EXTENDS FROM 10N85W TO 08N90W TO 08N111W 
WHERE LOW LEVEL WINDS SUGGEST A TRANSITION TO ITCZ WHICH EXTENDS 
TO 09N115W TO 11N132W TO BEYOND 10N140W. SCATTERED MODERATE 
ISOLATED STRONG CONVECTION WAS NOTED WITHIN 90 NM N AND 60 NM S 
OF MONSOON TROUGH BETWEEN 97W AND 111W. SCATTERED MODERATE 
CONVECTION WAS NOTED WITHIN 90 NM N AND 30 NM S OF ITCZ BETWEEN 
120W AND 125W. SCATTERED MODERATE CONVECTION WAS NOTED WITHIN 90 
NM OF ITCZ W OF 130W. 

...DISCUSSION... 

HIGH PRESSURE OF 1030 MB CENTERED N OF THE AREA NEAR 39N140W 
EXTENDS A RIDGE SE ACROSS THE FORECAST WATERS TO NEAR 17N111W. 
THE PRESSURE GRADIENT BETWEEN THE HIGH PRESSURE AND LOWER 
PRESSURE IN THE VICINITY OF THE ITCZ IS MAINTAINING A SMALL AREA 
OF FRESH TO STRONG TRADES FROM 10N TO 15N W OF 132W. THE AREA OF 
HIGH PRESSURE WILL REMAIN N OF THE AREA TROUGH MON MORNING 
MAINTAINING THIS SMALL AREA OF FRESH TO STRONG TRADES. 

LONG PERIOD NW SWELLS...WITH WAVE PERIODS BETWEEN 19-21 SEC 
ALONG THE LEADING EDGE...ARE MOVING ACROSS THE FAR NW PORTION OF 
THE FORECAST AREA. THE SWELL WILL CONTINUE TO PROPAGATE SE  
COVERING MUCH OF THE FORECAST AREA W OF 110W BY MON MORNING. 

GULF OF TEHUANTEPEC...THE NEXT GAP WIND EVENT IS EXPECTED TO 
BEGIN MON MORNING WITH WINDS RAPIDLY INCREASING TO GALE FORCE 
DURING THE AFTERNOON HOURS. WINDS WILL FURTHER INCREASE TO 40 KT 
MON EVENING AND TO 45 KT MON NIGHT WITH BUILDING SEAS TO 18-19 
FT. THE GALE FORCE GAP WIND EVENT IS EXPECTED TO PERSIST THROUGH 
TUE NIGHT. FRESH WINDS AND SEAS TO 8 FT DOWNSTREAM OF THE GULF 
WILL REACH AS FAR AS 105W BY TUE NIGHT. 

GULF OF PAPAGAYO...WINDS WILL PULSE OVER THE GULF OF PAPAGAYO 
PEAKING NEAR 25 KT DURING THE LATE NIGHT AND EARLY MORNING HOURS 
WITH THE ADDED COMPONENT OF NOCTURNAL DRAINAGE FLOW.  

GULF OF CALIFORNIA...HIGH PRES WILL BUILD ACROSS THE GREAT BASIN 
REGION THROUGH THE WEEKEND. BY EARLY MON...THE PRESSURE GRADIENT 
BETWEEN THE AREA OF HIGH PRESSURE AND TROUGHING OVER MEXICO WILL 
STRENGTHEN WINDS OVER THE GULF OF CALIFORNIA WITH SEAS BUILDING 
TO NEAR 7 FT. 
 
$$
AL