000
AXPZ20 KNHC 312140
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.

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

THE MONSOON TROUGH EXTENDS FROM 06N78W TO 09N110W. ITCZ 
CONTINUES FROM 09N110W TO 05N140W. SCATTERED MODERATE CONVECTION 
IS NOTED WITHIN 30 NM EITHER SIDE OF MONSOON TROUGH AXIS BETWEEN 
79W AND 81W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS 
NOTED FROM 09N TO 11N BETWEEN 96W AND 99W. SCATTERED MODERATE 
ISOLATED STRONG CONVECTION ALSO NOTED FROM 10N TO 14N BETWEEN 
108W AND 114W. NUMEROUS MODERATE ISOLATED STRONG CONVECTION 
PERSISTS ALONG COAST OF MEXICO N OF 17N BETWEEN 102W AND 104W.

...DISCUSSION...

A SHARP LONG WAVE UPPER TROUGH EXTENDS FROM THE NORTHERN PLAINS 
STATES...ACROSS NORTHERN BAJA CALIFORNIA...TO NEAR 05N140W. 
UPPER DIVERGENCE ALOFT ON THE SE SIDE OF THIS FEATURE HAS BEEN 
SUPPORTING CLUSTERS OF SHOWERS AND THUNDERSTORMS FOR THE PAST 
SEVERAL DAYS AS THE UPPER TROUGH PUSHES EAST. CURRENTLY...ONE OF 
THESE CLUSTERS IS MOVING ONSHORE OVER THE COAST OF THE MEXICAN 
STATE OF GUERRERO NEAR ACAPULCO. ADDITIONAL SHOWERS AND 
THUNDERSTORMS CAN BE EXPECTED OVER THE COAST OF SOUTHERN MEXICO 
THROUGH TUE AS THE UPPER TROUGH LINGERS OVER THE AREA. 

A SURFACE TROUGH ASSOCIATED WITH THE UPPER TROUGH APPEARS TO BE 
FORMING ALONG 110W N OF THE MONSOON TROUGH/ITCZ AXIS. THIS IS 
INTERACTING WITH 1029 MB HIGH PRES CENTERED NEAR 31N128W TO 
MAINTAIN A BROAD WEDGE SHAPED AREA OF 20 TO 25 KT TRADE WINDS 
ACROSS THE E PACIFIC FROM ROUGHLY 10N TO 20N W OF 110W. SEAS IN 
THIS AREA ARE 8 TO 12 FT IN FRESH NE WIND WAVES MIXING WITH 
LONGER PERIOD NW SWELL THAT COVERS MOST OF THE AREA W OF 110W. 

FARTHER NORTH...A SECOND ROUND OF NW SWELL CONTINUES TO PUSH 
INTO THE AREA COVERING N OF 22N W OF 135W. BY LATE TUE...FRESH 
TO STRONG SW WILL PRECEDE A COLD FRONT APPROACHING THE FAR NW 
CORNER OF THE DISCUSSION AREA...BUT DIMINISH THROUGH WED AS THE 
FRONT SHIFTS E. THIS WILL ALSO WEAKEN THE HIGH PRES CURRENTLY 
ALONG 30N...ALLOWING THE AREA OF TRADE WINDS OVER THE DEEP 
TROPICS TO SHRINK IN SIZE FROM THE EAST. 

GULF OF TEHUANTEPEC...WINDS OVER THE GULF OF TEHUANTEPEC HAVE 
DIMINISHED BELOW GALE FORCE...AND WILL CONTINUE TO RAPIDLY 
DIMINISH AS HIGH PRES N OF THE AREA WEAKENS AND SHIFTS EAST. 

GULF OF PAPAGAYO...SIMILARLY STRONG AND PERSISTENT GAP FLOW 
THROUGH THE GULF OF PAPAGAYO WILL START TO DIMINISH THROUGH TUE. 
NE TO E SWELL FROM THESE EVENTS WILL PERSIST FOR ANOTHER COUPLE 
OF DAYS FROM GENERALLY 05N TO 12N BETWEEN 95W AND 110W...MIXING 
WITH NW SWELL W OF 105W BY TUE.

GULF OF CALIFORNIA...HIGH PRES BUILDING OVER THE GREAT BASIN 
ALONG WITH LOW PRES OVER N CENTRAL MEXICO WILL ALLOW NW WINDS TO 
INCREASE TO 20 TO 25 KT OVER MUCH OF THE GULF OF CALIFORNIA 
STARTING TOMORROW...PERSISTING THROUGH EARLY THU.

$$
CHRISTENSEN