000
AXPZ20 KNHC 270332
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC THU DEC 27 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0300 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM 06N77W TO 05N92W. ITCZ EXTENDS 
FROM 05N92W TO 08N105W TO 07N140W. SCATTERED MODERATE CONVECTION 
IS NOTED WITHIN 90 NM N OF ITCZ AXIS BETWEEN 112W AND 118W.

...DISCUSSION...

THE MAIN ISSUE IS THE ONSET OF GALE FORCE WINDS THROUGH THE GULF 
OF TEHUANTEPEC THIS AFTERNOON. RECENT REPORTS FROM IXTEPEC ON 
THE PACIFIC SIDE OF THE GULF OF TEHUANTEPEC INDICATE GUSTS TO 35 
KT...INDICATIVE OF SUSTAINED CONDITIONS OVER THE ADJACENT GULF 
OF TEHUANTEPEC WATERS...PERSISTING THROUGH THE NIGHT ACROSS THE 
GULF OF TEHUANTEPEC. THE COLD HIGH PRES N OF AREA RESPONSIBLE 
FOR THE GALE WILL MODIFY AND SHIFT E RAPIDLY THROUGH THE NIGHT 
AS WELL...ALLOWING GAP WINDS TO DIMINISH THROUGH LATE THU. 
LOOKING AHEAD...GLOBAL MODELS INDICATE THE NEXT GALE EVENT FOR 
THE GULF OF TEHUANTEPEC WILL BE LATE SAT INTO SUN MORNING.

WINDS WILL PULSE THROUGH THE GULF OF PAPAGAYO OVER THE NEXT 
COUPLE OF DAYS WITH STRONGEST WINDS OCCURRING DURING THE 
OVERNIGHT AND EARLY MORNING HOURS WITH THE AID OF NOCTURNAL 
DRAINAGE FLOW. 

AN UPPER TROUGH EXTENDING FROM A LOW PRES SYSTEM MOVING INTO THE 
GREAT BASIN TO 25N140W AND MIGRATING EASTWARD INTO THE 
CALIFORNIA COAST IS SUPPORTING A COLD FRONT MOVING THROUGH 
SOUTHERN CALIFORNIA INTO NORTHERN BAJA. THE SOUTHERN EXTENT OF 
THE UPPER TROUGH EXTENDING FROM 30N135W TO 20N140W IS BECOMING 
CUT OFF FROM THE MAIN FLOW. AS A RESULT...THE ASSOCIATED FRONTAL 
BOUNDARY EXTENDING EAST TO WEST N OF 28N W OF 120W IS STALLING 
AND WEAKENING. 

FARTHER SOUTH...ASCAT PASSES FROM 1745 UTC AND 1930 UTC 
INDICATED FRESH TO STRONG NE TRADE WINDS REMAIN ACTIVE FROM 11N 
TO 18N W OF 130W. THE AREAL EXTENT OF THESE TRADES HAS BEEN 
SHRINKING AS THE UPPER TROUGH AND ASSOCIATED FRONT PUSHED SOUTH 
OF 30N AND ERODED THE SURFACE RIDGE IN THE AREA ALONG 28N. GFS 
AND ECMWF OUTPUT INDICATES THE CUT OFF PORTION OF THE UPPER 
TROUGH WILL SHIFT EASTWARD N OF 20N REACHING 120W BY LATE FRI. 
THIS WILL SUPPORT DEVELOPMENT OF A WEAK SURFACE TROUGH ALONG THE 
ITCZ BETWEEN 115W AND 120W...WHICH IN TURN WILL SUPPORT ENHANCED 
TRADES WINDS TO 20 TO 25 KT FROM 10N TO 15N NEAR THE TROUGH.

$$
CHRISTENSEN