000
AXPZ20 KNHC 161602
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SUN DEC 16 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 
1430 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
MONSOON TROUGH EXTENDS FROM 08.5N75W TO 06.5N79W TO 10N84W TO 
06N108W...WHERE IT TRANSITIONS TO ITCZ AXIS...CONTINUING ON TO 
06N130W TO BEYOND 05.5N140W. ISOLATED TO SCATTERED MODERATE 
CONVECTION NOTED WITHIN 150 NM S OF TROUGH AXIS BETWEEN 80W AND 
84W...AND WITHIN 180 NM N OF AXIS BETWEEN 98W AND 126W. 
SCATTERED MODERATE TO STRONG CONVECTION NOTED FROM 06.5N TO 15N 
W OF 129W. 

...DISCUSSION...

DEEP LAYERED HIGH PRESSURE REMAINS CENTERED OVER THE E CENTRAL 
PACIFIC...N OF THE HAWAIIAN ISLANDS...WITH A 1029 MB SURFACE 
HIGH CENTERED NEAR 32N152W. THE ASSOCIATED BROAD SURFACE RIDGE 
EXTENDS W TO E AND DOMINATES MUCH OF THE CENTRAL PACIFIC...AND 
EXTENDS E-SE ACROSS THE LOCAL AREA TO NEAR 19N111W. A TIGHT 
PRESSURE GRADIENT PERSISTS BETWEEN THE RIDGE AND LOWER PRESSURE 
IN THE VICINITY OF THE ITCZ...AND IS MAINTAINING A NE TO SW 
ALIGNED ZONE OF FRESH TO STRONG TRADEWINDS FROM 07N TO 21N W OF 
130W AND FROM 09N TO 18N BETWEEN 120W AND 130W...WHERE SEAS ARE 
RUNNING 8 TO 12 FT. THIS ZONE OF STRONG TRADEWINDS CONTINUES WWD 
WELL BEYOND 140W AND INTO THE TROPICAL CENTRAL PACIFIC...DUE S 
OF THE SURFACE HIGH. THESE WINDS WERE DEPICTED WELL IN OVERNIGHT 
SCATTEROMETER PASSES. TO THE E...A SUFFICIENT PRESSURE GRADIENT 
ALSO PERSISTS BETWEEN THE E END OF THE RIDGE AND A TROUGH OF LOW 
PRESSURE ALONG THE SIERRA MADRE OCCIDENTALES OF MEXICO...AND IS 
MAINTAINING AN AREA OF FRESH TO LOCALLY STRONG NW TO N WINDS OFF 
THE COAST OF MEXICO FROM 17N TO 21N E OF 108W. MODERATE NW SWELL 
MOVING THROUGH THOSE REGIONAL WATERS IS MIXING WITH NLY WIND 
WAVES TO PRODUCE SEAS 6-8 FT ACROSS THE AREA. THIS AREA OF FRESH 
WINDS WILL SHIFT N INTO S PORTIONS OF THE GULF OF CALIFORNIA 
THIS EVENING THROUGH MON EVENING BEFORE DIMINISHING.

THE DEEP LAYERED RIDGING WILL PERSIST THROUGH MON MORNING... 
WITH THE SURFACE RIDGE PREVAILING OVER THE NORTHERN PART OF THE 
AREA...BEFORE IT GRADUALLY WEAKENS MON THROUGH EARLY TUE AHEAD 
OF AN APPROACHING STRONG COLD FRONT. THIS WILL ACT TO DECREASE 
THE AREAL COVERAGE OF FRESH TO STRONG TRADEWINDS AS WELL AS 
DIMINISH WINDS OFF THE COAST OF MEXICO AND THE S GULF OF 
CALIFORNIA BY MON NIGHT. THIS STRONG COLD FRONT IS EXPECTED TO 
ENTER THE NW PART OF THE FORECAST AREA BY LATE MON NIGHT AND 
QUICKLY REACH BAJA CALIFORNIA NORTE TUE EVENING. STRONG HIGH 
PRES BUILDING BEHIND THE FRONT WILL INDUCE FRESH TO STRONG WINDS 
N TO NE WINDS BEHIND THE FRONT....WITH BUILDING SEAS IMMEDIATELY 
BEHIND THE FRONT IN LARGE NW SWELL.

GAP WINDS...    
SOUTHERLY RETURN FLOW HAS DEVELOPED ACROSS THE GULF OF MEXICO 
DURING THE PAST 24-36 HOURS...AND ENDED THE NORTHERLY FORCING 
TYPICALLY NEEDED FOR N GAP WINDS THROUGH THE GULF OF 
TEHUANTEPEC...WHERE WINDS ARE NOW LIGHT AND VARIABLE. 
HOWEVER...A SIGNIFICANT GAP WIND EVENT ACROSS THE GULF OF 
TEHUANTEPEC IS LIKELY BY THE END OF THE WEEK AS THE STRONG FRONT 
MOVING ACROSS THE DISCUSSION AREA LATE MON THROUGH WED FINALLY 
SWEEPS ACROSS THE GULF OF MEXICO...FORCING POTENTIAL STORM FORCE 
WINDS THROUGH THE GULF OF TEHUANTEPEC BY SUNRISE FRI. ELSEWHERE 
ALONG THE PACIFIC COASTS OF CENTRAL AMERICA...LIGHT TO MODERATE 
GAPS WINDS PREVAIL THIS MORNING AS ONLY LIGHT TO MODERATE E TO 
NE TRADE WINDS PREVAIL ACROSS THE W AND SW CARIBBEAN. GAP WINDS 
THERE WILL ALSO FRESHEN FRI INTO NEXT WEEKEND AS THE STRONG 
FRONTAL SYSTEM MOVES ACROSS THE GULF OF MEXICO.

$$
STRIPLING