000
AXPZ20 KNHC 071549
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SAT JAN 07 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 
1545 UTC.

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

MONSOON TROUGH AXIS EXTENDS FROM 07N77W TO 05N80W TO 08N86W TO 
05N93W...WHERE IT TRANSITIONS TO ITCZ...CONTINUING ON TO 06N115W 
TO 09N135W TO BEYOND 07N140W. SCATTERED MODERATE CONVECTION 
NOTED WITHIN 60-90 NM EITHER SIDE OF THE AXIS BETWEEN 130W AND 
135W. 

...DISCUSSION...

A 1032 MB HIGH PRES IS CENTERED N OF THE AREA NEAR 38N132W WITH 
RIDGE EXTENDING SE TO NEAR 22N115W. THE PRESSURE GRADIENT 
BETWEEN THE AREA OF HIGH PRESSURE AND LOWER PRESSURE IN THE 
VICINITY OF THE ITCZ IS MAINTAINING FRESH TRADEWINDS IN AN AREA 
FROM 09N TO 19N W OF LINE FROM 09N130W TO 19N133W. LONG PERIOD 
NW SWELL WITH PERIODS OF 18-20 SECONDS ALONG THE LEADING EDGE OF 
THE SWELL TRAIN CONTINUES TO MOVE SE THROUGH THE FORECAST WATERS
WITH COMBINED SEAS 8 TO 12 FT CURRENTLY COVERING MUCH OF THE 
AREA W OF 120W. THESE SWELLS WILL CONTINUE TO PROPAGATE SE 
THROUGH THE WEEKEND WHILE SLOWLY SUBSIDING W OF 120W THROUGH 
SUN. 

THE PRESSURE GRADIENT BETWEEN THE HIGH PRESSURE CENTER MENTIONED 
ABOVE AND TROUGHING ACROSS SRN CALIFORNIA IS PRODUCING FRESH 
NORTHERLY WINDS N OF 27N BETWEEN 118W AND 128W...WITH SEAS AS 
HIGH AS 15 FT ALONG THE BORDER AT 30N SHIFTING SE. AS THE AREA 
OF HIGH PRESSURE WEAKENS OVER THE WEEKEND...WINDS WILL DIMINISH 
BELOW 20 KT BY EARLY SUN. 

GULF OF TEHUANTEPEC...WITH THE AIR MASS OVER THE GULF OF MEXICO 
FURTHER MODIFIED...THE DENSITY DIFFERENCE BETWEEN THE AIR MASS 
OVER THE GULF OF MEXICO AND THE EASTERN PACIFIC HAS DECREASED. 
THIS HAS REDUCED FLOW THROUGH THE CHIVELA PASS INTO THE GULF OF 
TEHUANTEPEC...AND EXCEPT FOR NOCTURNAL DRAINAGE FLOW NEAR 20 
KT...WINDS GENERALLY WILL REMAIN BELOW 20 KT THROUGH MON.

GULF OF PAPAGAYO...FRESH TO STRONG NORTHEASTERLY GRADIENT WIND 
OVER THE WESTERN CARIBBEAN IS FLOWING THROUGH THE GAPS IN THE 
TOPOGRAPHY OVER NICARAGUA AND COSTA RICA AND SPILLING THROUGH 
THE GULF OF PAPAGAYO. WINDS WILL PEAK NEAR 25 KT DURING THE 
EARLY MORNING HOURS WITH THE ADDED COMPONENT OF NOCTURNALLY 
DRIVEN KATABATIC WINDS AND THEN REDUCE TO AROUND 20 KT 
THROUGHOUT THE DAY AND EVENING HOURS. LITTLE CHANGE IN THIS 
PATTERN IS EXPECTED THROUGH EARLY MON.

N TO NE SWELL PRODUCED FROM THE COMBINED STRONG GAP FLOW FROM 
PAPAGAYO AND TEHUANTEPEC COVERS MUCH OF THE AREA S OF 15N 
BETWEEN 100W AND 120W. THESE SWELLS ARE MIXING WITH NW SWELL 
MOVING THROUGH THE WATERS W OF 120W...AND CAUSING CONFUSED SEAS. 

HIGH PRESSURE IS FORECAST TO BUILD ACROSS THE GREAT BASIN REGION 
TONIGHT AND SUN. THIS WILL TIGHTEN THE PRES GRADIENT THROUGH THE 
GULF OF CALIFORNIA ON SUN AND LEAD TO NWLY WINDS INCREASING TO 
20 TO 25 KT BY SUN MORNING...GRADUALLY SPREADING S THROUGH THE 
GULF TO 25N BY SUN AFTERNOON. ALTHOUGH NOT CURRENTLY FORECAST...
IN HOUSE DIAGNOSTIC TOOLS SUGGEST WINDS MAY REACH 30 KT BRIEFLY 
LATE SUN AND SUN NIGHT. SOME OF THIS GRADIENT WIND WILL VEER NE 
AND FLOW ACROSS THE BAJA PENINSULA AND SPILL THROUGH THE 
TOPOGRAPHIC GAPS AND OFFSHORE OF THE W COAST OF BAJA SUNDAY 
NIGHT AND MONDAY MORNING...PRODUCING GAP WINDS AROUND 20 KT. 

$$
COBB