000
AXPZ20 KNHC 311547
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC MON DEC 31 2012

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 NW FROM THE COLOMBIAN COAST AT 08N78W 
ALONG THE PACIFIC COAST OF COSTA RICA TO 09N86W...THEN TURNS SW 
INTO A CYCLONIC CIRCULATION NEAR 05N91W...THEN NW TO 09N108W 
WHERE IT TRANSITIONS TO AN ITCZ. THE ITCZ CONTINUES W TO 09N108W 
TO 08N120W THEN SW THROUGH 05N135W TO BEYOND 05N140W. SCATTERED 
MODERATE ISOLATED STRONG CONVECTION IS OBSERVED FROM 10N TO 17N 
BETWEEN 103W AND 110W.

A SURFACE TROUGH EXTENDS NNE FROM 10N120W TO 15N118W. GFS MODEL 
GUIDANCE SHIFTS THE TROUGH E...FROM 10N115W TO 20N106W TUE... 
ACCOMPANIED BY A NE-E-SE 10-15 KT WIND SHIFT ALONG THE TROUGH 
AXIS. GFS MODEL MAY BE ERRONEOUSLY MOVING THIS TROUGH EASTWARD 
WHEN IN FACT A SECOND TROUGH MAY DEVELOP UNDER THE LARGE AREA OF 
CONVECTION CURRENTLY CENTERED ON 15N106W.

...DISCUSSION...

1028 MB HIGH CENTERED AT 30N134W WITH A RIDGE EXTENDING SE TO 
19N106W. ANTICYCLONIC NE-E-SE 10-15 KT WINDS ARE OBSERVED ACROSS 
THE SUB-TROPICS W OF 125W WHILE NW-N 15-20 KT WINDS ARE OBSERVED 
E OF 125W TO THE BAJA PENINSULA.  NE TRADES ACROSS THE TROPICS S 
OF THE SURFACE RIDGE...FROM 10-20N W OF 115W...CONTINUE AT 20-25 
KT WITH SEAS 8-12 FT IN MIXED NE AND NW SWELL. ELSEWHERE W OF 
LINE FROM 23N112W TO 12N112W TO 04N140W SURFACE WINDS ARE N-NE 
AT 10-20 KT WITH SEAS 7-10 FT PRIMARILY DUE TO LONG PERIOD NE 
AND NW SWELL.

THE HIGH WILL DRIFT E THROUGH TUE THEN SLIGHTLY SE TO 28N128W ON 
WED. THIS WILL MAINTAIN THE FRESH TO STRONG TRADES FROM 07-17N W 
OF 130W WITH SEAS 9-12 FT IN A BROAD MIX OF SWELL. LARGE LONG 
PERIOD NW SWELL MOVING INTO THE NW WATERS N OF 23N W OF 136W ARE 
EXPECTED TO DRIVE SEAS UP TO 13 FT TONIGHT. THESE SWELLS WILL 
SPREAD EASTWARD BUT GRADUALLY SUBSIDE WITH SEAS 6-9 FT REACHING 
THE NORTHERN BAJA PENINSULA LATE TUE NIGHT. A COLD FRONT WILL 
ENTER THE WATERS NEAR 30N140W TUE NIGHT ACCOMPANIED BY A 20-25 
KT SW-NW WIND SHIFT WITH SOUTHERLY GALE WINDS PRECEDING THE 
FRONT OVER THE WATERS N OF 31N. THE HIGH WILL EFFECTIVELY BLOCK 
THE FRONT AND CAUSE IT TO DISSIPATE OVER THE NW WATERS WED-FRI.
 
GULF OF TEHUANTEPEC...NORTHERLY WINDS HAVE DECREASED TO MINIMAL 
GALE AND SHOULD DIMINISH JUST AFTER THIS MORNINGS DIURNAL 
MAXIMUM DRAINAGE...BY 15 UTC...AND CONTINUE TO DIMINISH TO LESS 
THAN 20 KT BY THIS EVENING. THE NEXT EVENT STARTS WED NIGHT.  

GULF OF PAPAGAYO...NE-E 15-25 KT SURGES ARE EXPECTED TO CONTINUE 
AS FAR W AS 94W WHERE THE ASSOCIATED NE SWELLS ARE MIXING WITH 
SW CROSS EQUATORIAL SWELL...AS WELL AS N-NW SWELL PROPAGATING S 
FROM THE TEHUANTEPEC EVENT. THE GRADIENT WILL RELAX LATE TUE. 

GULF OF CALIFORNIA...NW WINDS AT 10-15 KT WILL INCREASE TO 15-20 
KT TONIGHT AND 20-25 KT LATE TUE THROUGH EARLY THU.

$$
MUNDELL