000
AXPZ20 KNHC 270959
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0945 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM 08N78W TO 09N86W TO 04N92W WHERE
LOW LEVEL WINDS SUGGEST THE ITCZ BEGINS...AND CONTINUES TO 
04N92W TO 09N110W TO 08N120W TO 08N140W. SCATTERED MODERATE 
CONVECTION IS WITHIN 60 NM S OF THE ITCZ AXIS BETWEEN 110W-113W
...AND WITHIN 120 NM N OF THE ITCZ AXIS BETWEEN 113W-117W. 

...DISCUSSION...

AN UPPER TROUGH MOVING EASTWARD EXTENDS FROM A LOW PRES SYSTEM 
MOVING INTO THE GREAT BASIN SW THROUGH 32N122W TO 26N132W TO 
17N140W. THE TROUGH SUPPORTS A DISSIPATING COLD FRONT ACROSS
FAR NW MEXICO AND NORTHERN BAJA CALIFORNIA. AMPLE UPPER LEVEL
MOISTURE IN THE FORM OF MOSTLY BROKEN HIGH CLOUDS ARE NOTED 
STREAMING ENE TO SE OF THE TROUGH AS FAR SE TO A LINE FROM 
MANZANILLO MEXICO TO 10N108W. BROKEN LOW AND MID LEVEL CLOUDS 
MOVING WSW WITH ISOLATED SHOWERS AND TSTMS ARE UNDERNEATH THE 
HIGH CLOUDS.

THE AFOREMENTIONED UPPER TROUGH IS IN BETWEEN A HIGHLY AMPLIFIED
RIDGE JUST TO THE W OF THE AREA...AND ANOTHER ONE OVER THE SE 
PORTION OF THE AREA BETWEEN 92W AND 130W WITH A MEAN RIDGE AXIS 
ALONG 19N104W 13N105W 06N110W. AN UPPER TROUGH OVER THE FAR 
EASTERN PART OF THE AREA EXTENDS FROM HONDURAS S TO 08N88W...AND 
THEN SE TO NEAR 01N79W. SATELLITE WATER VAPOR IMAGERY SHOWS 
EXTENSIVE MODERATE SUBSIDENCE MAINTAINING A RATHER STABLE 
ATMOSPHERIC ENVIRONMENT OVER THE AREA TO THE SE OF THE HIGH 
CLOUDINESS MENTIONED ABOVE. ONLY INTERMITTENT ISOLATED TSTMS ARE 
NOTED THERE.

THE UPPER TROUGH THAT EXTENDS FROM 32N122W TO 26N132W TO 17N140W
IS FORECAST TO BECOME ABSORBED WITH A BROAD TROUGH THAT DEVELOPS 
OVER THE W CENTRAL PORTION OF THE AREA LATE FRI IN RESPONSE TO 
AN UPPER LEVEL LOW THAT DIVES SEWD TOWARDS CENTRAL CALIFORNIA. 
AN ASSOCIATED WEAK COLD FRONT IS EXPECTED TO SWEEP SE ACROSS THE 
FAR NE WATERS LATE FRI INTO SAT. PRIOR TO THIS ON THU...A 1028 
MB HIGH CENTER ANALYZED N OF THE AREA AT 35N134W WITH A RIDGE SE 
TO SOUTHERN BAJA CALIFORNIA WILL SHIFT SE TO NEAR 32N130W WHILE 
WEAKENING SLIGHTLY. AN ASCAT PASS FROM 0636 UTC THIS MORNING 
REVEALED FRESH TO STRONG NE TRADES OVER THE WESTERN PORTION 
WITHIN THE AREA ROUGHLY FROM 10N TO 21N W OF 130W...AND ALSO 
FROM 09N TO 17N BETWEEN 120W AND 130W WHERE SEAS ARE 9 TO 11 FT 
IN MIXED NW AND NE SWELLS. WITH THE 1028 MB HIGH FORECAST TO 
WEAKEN...THE RESULTANT PRES GRADIENT TO ITS S WILL SLACKEN SOME 
ALLOWING FOR THE TRADES TO DIMINISH SLIGHTLY IN LATITUDINAL 
EXTENT THROUGH THIS EVENING. STRONGER HIGH PRES THEN BUILDS SE 
INTO THE AREA BEGINNING FRI INCREASING THE PRES GRADIENT OVER 
MUCH OF THE WESTERN AND CENTRAL PORTIONS FURTHER ENHANCED WITH 
THE DEVELOPMENT OF A SURFACE TROUGH IN THE GENERAL VICINITY OF 
119W/120W FROM 11N TO 17N FORECAST TO MOVE WESTWARD. THE 
INCREASING PRES GRADIENT SHOULD LEAD TO TRADES INCREASING ONCE 
AGAIN IN AREAL COVERAGE OVER THOSE AREAS. LARGE NW SWELLS WILL 
GENERATE SEAS OF 8 TO 13 FT NW OF A LINE FROM ABOUT 26N115W TO 
10N122W TO 05N140W OVER THE NEXT 24 TO 48 HRS. THE HIGHEST OF 
THESE SEAS ARE EXPECTED TO BE CONFINED TO N OF AROUND 26N AND 
BETWEEN 119W AND 127W.

GAP WINDS...
THE 0314 HIGH RESOLUTION ASCAT PASS INDICATED N GALE FORCE WINDS 
OF 30-35 KT THROUGH THE GULF OF TEHUANTEPEC AND S TO NEAR 15N 
BETWEEN 94W AND 96W AS A VERY TIGHT PRES GRADIENT PREVAILS 
ACROSS SE MEXICO. THE COLD HIGH PRES N OF AREA RESPONSIBLE FOR 
THESE GALE CONDITIONS IS FORECAST TO MODIFY AND SHIFT EASTWARD 
THROUGH THIS AFTERNOON ALLOWING FOR THESE WINDS TO DIMINISH TO 
20 KT OR LESS.

NE TO E WINDS OF 20-25 KT WILL PULSE THROUGH THE GULF OF 
PAPAGAYO THROUGH THE NEXT 48 HRS MAINLY DURING THE OVERNIGHT AND 
EARLY MORNING HOURS WITH THE AID OF NOCTURNAL DRAINAGE FLOW.  

$$
AGUIRRE