000
AXPZ20 KNHC 281509
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC FRI DEC 28 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 FROM 08N82W TO 07N90W WHERE LOW LEVEL 
WINDS SUGGEST A TRANSITION TO ITCZ WHICH EXTENDS TO 09N120W TO 
06N130W TO BEYOND 07N140W. SCATTERED MODERATE ISOLATED STRONG 
CONVECTION WAS NOTED WITHIN 120 NM S OF AXIS BETWEEN 82W AND 
87W. SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS NOTED 
FROM 09N TO 13N BETWEEN 113W AND 122W. SCATTERED MODERATE 
CONVECTION WAS NOTED WITHIN 90 NM N OF AXIS W OF 135W.

...DISCUSSION...

HIGH PRESSURE 1025 MB IS CENTERED N OF THE AREA NEAR 31N137W 
WITH RIDGE EXTENDING SE TO NEAR 19N111W. THE PRESSURE GRADIENT 
BETWEEN THIS AREA OF HIGH PRESSURE AND LOWER PRESSURE IN THE 
VICINITY OF THE ITCZ IS MAINTAINING FRESH TO STRONG TRADEWINDS 
FROM 10N TO 20N W OF 125W. THE RIDGE WILL REMAIN THROUGH THE 
FORECAST PERIOD...MAINTAINING THE AREA OF FRESH TO STRONG 
TRADEWINDS.

MUCH OF THE AREA N OF 20N W OF 115W ARE DOMINATED BY NORTHERLY 
SWELLS IN THE 8 TO 11 FT RANGE. A WEAK FRONT WILL MOVE INTO THE 
NW PART OF THE FORECAST AREA BY EARLY SAT. THOUGH WINDS BEHIND 
THE FRONT WILL REMAIN LESS THAN 20 KT...IT WILL USHER IN A FRESH 
SET OF NW SWELLS INTO THE AREA...WITH SEAS REACHING NEAR 13 FT 
BY SUN MORNING. THE AREA FROM 10N TO 20N W OF 120W IS DOMINATED 
BY MIXED NW SWELL AND NE TRADEWIND SWELL. THESE SWELLS WILL 
MAINTAIN THROUGH THE FORECAST PERIOD. 

GAP WINDS...

WINDS WILL PULSE ACROSS THE GULF OF PAPAGAYO OVER THE NEXT 
COUPLE OF DAYS. WINDS WILL PEAK EACH NIGHT NEAR 25 KT DURING THE 
OVERNIGHT AND EARLY MORNING HOURS WITH THE ADDED COMPONENT OF 
NOCTURNAL DRAINAGE FLOW...THEN WILL DIMINISH BELOW 25 KT DURING 
THE AFTERNOON AND EARLY EVENING HOURS. 

GULF OF TEHUANTEPEC...A COLD FRONT JUST OFF THE TEXAS COAST WILL 
REACH THE NW BAY OF CAMPECHE SAT MORNING WITH THE NORTHERLY 
WINDS SURGING THROUGH THE CHIVELA PASS INTO THE GULF OF 
TEHUANTEPEC BY SAT AFTERNOON. THESE N WINDS WILL RAPIDLY BUILD 
TO GALE FORCE SAT EVENING...WITH NEAR STORM CONDITIONS EXPECTED 
OVERNIGHT SATURDAY. 

$$
AL