000
AXPZ20 KNHC 061549
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC FRI JAN 06 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 COLOMBIA NEAR 07N77W TO 06N85W 
TO 04N92W...WHERE IT TRANSITIONS TO ITCZ...CONTINUING ON TO 
03N96W TO 07N110W TO 09N135W TO BEYOND 07N140W. SCATTERED 
MODERATE CONVECTION NOTED WITHIN 90-120 NM EITHER SIDE OF AXIS 
BETWEEN 96W AND 125W...AND WITHIN 90 NM S OF AXIS BETWEEN 130W 
AND 138W.

...DISCUSSION...

ALOFT...MIDDLE TO UPPER LEVEL RIDGING CONTINUES ACROSS MUCH OF 
EASTERN PORTIONS OF THE AREA...FROM NEAR 10N100W EXTENDING NW TO 
32N122W. A MIDDLE TO UPPER LEVEL CYCLONE OVER SE TEXAS...CUT OFF 
FROM THE MEAN FLOW ACROSS THE U.S. AND ASSOCIATED TROUGH AXIS 
DOMINATES THE FLOW OVER THE AREA E OF THE RIDGE...GENERALLY OVER
MEXICO E OF 105W. W OF THE RIDGE...A LINGERING MIDDLE TO UPPER 
LEVEL TROUGH EXTENDED FROM NEAR 33N135W TO SE OF THE BIG ISLAND 
OF HAWAII NEAR 13N155W. THE RIDGE WILL WEAKEN AND FLATTEN DURING 
THE NEXT 24 HOURS AS THE CUT OFF LOW SHIFTS E ACROSS THE NRN 
GULF...WHILE THE TROUGH TO THE W SHARPENS AND STRENGTHENS OVER 
THE WEEKEND...ALLOWING THE RIDGE TO REBUILD ABOUT 10 DEGREES TO 
THE W BY SUN.

AT LOWER LEVELS...A 1032 MB HIGH PRES IS CENTERED N OF THE AREA 
NEAR 39N132W WITH RIDGE EXTENDING SE TO NEAR 15N115W. THE 
PRESSURE GRADIENT BETWEEN THE HIGH PRESSURE AND LOWER PRESSURE 
IN THE VICINITY OF THE ITCZ TO THE S IS MAINTAINING A NARROW 
ZONE OF FRESH TRADEWINDS FROM 06N TO 10N W OF 118W...WHILE THIS 
ZONE BROADENS FROM 07N TO 22N W OF 138W. SEAS ARE NEAR 8 FT 
ACROSS THIS AREA E OF 130W...AND IN THE 9 TO 14 FT RANGE W OF 
130W AS LARGE LONG PERIOD NW SWELL CONTINUES TO MOVE INTO THE 
AREA. THESE LONG PERIOD NW SWELLS ARE CREATING SEAS OF 8 TO 14 
FT ACROSS THE NW HALF OF THE AREA THIS MORNING. A 0800 UTC JASON 
ALTIMETER PASS INDICATED SEAS OF 14 FT NEAR 30N128W. THESE SEAS
WILL MOVE SE AND GRADUALLY SUBSIDE BY SUN. 

GULF OF TEHUANTEPEC...DESPITE THE FACT THAT WINDS HAVE VEERED E 
TO SE OVER THE W GULF OF MEXICO...NLY WINDS CONTINUE TO FUNNEL 
THROUGH THE CHIVELA PASS INTO THE GULF OF TEHUANTEPEC DUE TO THE 
DIFFERENCES IN THE AIR MASSES BETWEEN THE GULF OF MEXICO AND THE 
EASTERN PACIFIC. THIS IS RESULTING IN 20-25 KT N WINDS. THE N TO 
NE WINDS CONTINUE DOWNSTREAM BEYOND 100W AND CONTINUE TO 
CONVERGE N OF THE ITCZ...FORCING MODEST CONVECTION ALONG AND N 
OF THE ITCZ MENTIONED ABOVE. AS THE AIR MASS ACROSS THE GULF OF 
MEXICO MODIFIES FURTHER...WIND SPEEDS WILL TREND DOWNWARD OVER 
THE GULF OF TEHUANTEPEC...WITH WINDS EXPECTED TO DIMINISH BELOW 
20 KT BY THIS EVENING. 

GULF OF PAPAGAYO...FRESH TO STRONG NORTHEASTERLY GRADIENT WIND 
FLOW OVER THE WESTERN CARIBBEAN IS FLOWING THROUGH THE GAP IN 
THE TOPOGRAPHY OVER NICARAGUA AND ACROSS THE GULF OF PAPAGAYO. 
THIS IS EXPECTED TO CONTINUE FOR AT LEAST ANOTHER 24 
HOURS...WITH WINDS PEAKING NEAR 25 KT DURING THE EARLY MORNING 
HOURS WITH THE ADDED COMPONENT OF NOCTURNALLY DRIVEN KATABATIC 
WINDS.

ELSEWHERE E OF 110W...N TO NE SWELL ASSOCIATED WITH THE COMBINED 
STRONG GAP FLOW FROM PAPAGAYO AND TEHUANTEPEC COVERS MUCH OF THE 
AREA S OF 15N BETWEEN 93W AND 120W. THESE SWELLS ARE MIXING WITH 
NW SWELL W OF 100W AND CAUSING CONFUSED SEAS. SEAS ACROSS THE 
AREA BETWEEN 100W AND 120W WILL BUILD TO 8 TO 10 FT THROUGH 
SUNDAY AS THE NW SWELL PROPAGATES THROUGH THE REGIONAL WATERS. 

HIGH PRESSURE IS FORECAST TO MOVE INTO THE NW U.S. OVER THE 
WEEKEND AND BUILD S INTO NRN MEXICO LATE SAT NIGHT INTO SUN. 
THIS WILL TIGHTEN THE PRES GRADIENT THROUGH THE GULF OF 
CALIFORNIA AND LEAD TO NWLY WINDS INCREASING TO 20 TO 25 KT SUN 
AND SUN NIGHT...BEFORE GRADUALLY DIMINISHING MON. 

$$
COBB