000
AXPZ20 KNHC 030948
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC MON DEC 03 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 
0900 UTC.

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

MONSOON TROUGH EXTENDS FROM 09N84W TO 06N100W TO 07N110W WHERE 
IT TRANSITIONS TO THE ITCZ EXTENDING TO 09N120W TO BEYOND 
07N140W. SCATTERED MODERATE CONVECTION IS WITHIN 60 NM OF TROUGH 
BETWEEN 105W AND 107W. SCATTERED MODERATE ISOLATED STRONG 
CONVECTION IS FROM 06N TO 10N BETWEEN 112W AND 128W. SIMILAR 
CONVECTION IS ALSO NOTED WITHIN 60 NM S OF ITCZ AXIS BETWEEN 
132W AND 135W.

...DISCUSSION...

ALOFT...AN UPPER LEVEL TROUGH EXTENDS FROM NW MEXICO THROUGH 
CENTRAL BAJA CALIFORNIA INTO THE EPAC WATERS ALONG 24N120W 
18N134W. MODERATE TO STRONG SUBSIDENCE AND IMPLIED DRY AIR MASS 
IS NOTED ALONG AND BEHIND THE TROUGH AXIS. SOME MID/UPPER LEVEL 
MOISTURE IS AVAILABLE AHEAD OF THE TROUGH AXIS WITH A WEAK JET 
CORE OF 50 KT OVER SOUTHERN BAJA CALIFORNIA AND NW MEXICO. SE OF 
THE TROUGH...UPPER DIFFLUENCE IS HELPING TO SUPPORT CONVECTION 
ALONG THE ITCZ AXIS PARTICULARLY FROM 06N TO 10N BETWEEN 112W 
AND 128W. A RIDGE COVERS NORTHERN SOUTH AMERICA...CENTRAL 
AMERICA AND THE PACIFIC WATERS E OF 100W. 

AT THE SURFACE...NW SWELLS GENERATED BY THE LARGE EXTRATROPICAL 
CYCLONE THAT WAS LOCATED OVER THE GULF OF ALASKA DURING THE 
PREVIOUS DAYS CONTINUE TO PUSH INTO THE FORECAST REGION WITH 
SEAS TO 10 FT IN THE NE PART OF THE AREA. THIS SWELL EVENT WILL 
CONTINUE TO PROPAGATE S AND E ACROSS THE REGIONAL WATERS WHILE 
SLOWLY SUBSIDING. SWELLS FROM THIS EVENT AT LEAST 8 FT CURRENTLY 
COVER MOST OF THE REGION WEST OF 110W. THIS SWELL EVENT IS 
FORECAST TO FADE BY TUESDAY. ON THIS DAY...ADDITIONAL PULSES OF 
NW SWELLS SHOULD REACH THE FAR NW PORTION RAISING SEAS TO 8 FT 
NW OF A LINE FROM 30N136W TO 28N140W BY TUE NIGHT.

A RELATIVELY WEAK 1022 MB HIGH PRESSURE IS CENTERED NEAR 26N130W 
WITH A RIDGE EXTENDING WESTWARD TO PAST 140W INCLUDING A 
SECONDARY HIGH PRESSURE 1021 MB CENTER AT 26N140W. THE PRESSURE 
GRADIENT BETWEEN THIS AREA OF HIGH PRESSURE AND LOWER PRESSURE 
IN THE VICINITY OF THE ITCZ IS MAINTAINING FRESH TO STRONG NE 
TRADEWINDS. SCATTEROMETER DATA CONFIRMED THE PRESENCE OF THESE 
WINDS. THIS WEATHER PATTERN WILL PERSIST DURING THE NEXT COUPLE 
OF DAYS AS HIGH PRES REMAINS NEARLY STATIONARY AND SLIGHTLY 
INTENSIFIES. THE MOST RECENT ALTIMETER PASS INDICATED SEA 
HEIGHTS OF 8-11 FT ACROSS THE N WATERS DUE TO THE NW SWELL EVENT 
AND IN THE REGION OF INCREASING TRADE WINDS. 

GAP WINDS...
FRESH TO STRONG N TO NE WINDS WILL CONTINUE TO FUNNEL THROUGH 
THE CHIVELA PASS INTO THE GULF OF TEHUANTEPEC WITH SEAS OF 8-9 
FT. DURING THE NEXT TWO DAYS...WINDS WILL PEAK NEAR 25 KT DURING 
THE OVERNIGHT AND EARLY MORNING HOURS WITH THE AID OF THE 
NOCTURNAL DRAINAGE FLOW. WINDS WILL THEN DIMINISH TO NEAR 20 KT 
DURING THE AFTERNOON HOURS. LOOKING AHEAD...GLOBAL MODELS 
CONTINUE TO INDICATED A NEW GULF OF TEHUANTEPEC GAP WIND EVENT 
OCCURRING WEDNESDAY AND THURSDAY...BUT LIKELY REMAINING BELOW 
GALE FORCE. ALL GLOBAL MODELS SHOW NORTHERLY WINDS OF 20-30 KT 
WITH BUILDING SEAS OF 8-10 FT.

WINDS WILL PULSE IN THE GULF OF PAPAGAYO TO 20 KT DURING THE 
OVERNIGHT HOURS THEN DIMINISHING BELOW 20 KT DURING THE 
AFTERNOON HOURS. 

$$
GR