000
AXPZ20 KNHC 161009
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC WED DEC 16 2015

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
0930 UTC.               
 
...SPECIAL FEATURE...

ONE OF THE STRONGEST COLD FRONTS OF THE SEASON THUS FAR IS
FORECAST TO MOVE SE ACROSS THE GULF OF MEXICO LATE THU AND
FRI...AND REACH THE CENTRAL BAY OF CAMPECHE THU EVENING.
NORTHERLY WINDS WILL BEGIN TO SPILL THROUGH THE ISTHMUS OF
TEHUANTEPEC THU EVENING AND QUICKLY REACH GALE FORCE AFTER
MIDNIGHT THU NIGHT. A 1030 MB HIGH PRES CENTER WILL MOVE INTO
CENTRAL TEXAS BEHIND THE COLD FRONT ON FRI AND FORCE A VERY
STRONG AND BROAD GULF OF TEHUANTEPEC GAP WIND EVENT FRI THROUGH
THE UPCOMING WEEKEND...WITH WINDS EXPECTED TO REACH 50 KT...
STORM FORCE...FRI AFTERNOON THROUGH EVENING...BEFORE WINDS
DIMINISH VERY SLIGHTLY TO THE 40-45 KT RANGE EARLY SAT THROUGH
SAT NIGHT. SEAS DOWNSTREAM OF TEHUANTEPEC WILL BUILD GREATER
THAN 20 FT BY FRI EVENING. 

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

A WEAK TROUGH EXTENDS FROM 08.5N83.5W TO 10N90W TO 08.5N99W TO
10N113W. ITCZ EXTENDS FROM 09.5N123W TO BEYOND 04.5N140W.
SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED WITHIN 240NM
NW AND 60 NM SE OF ITCZ W OF 123W. 
 
...DISCUSSION...

EXPANSIVE 1035 MB HIGH PRESSURE CENTERED NORTH OF THE AREA NEAR
36N135W IS SLOWLY DRIFTING SE. A RIDGE AXIS EXTENDS FROM THE
HIGH SOUTHEASTWARD TO NEAR 21N113W. A COLD FRONT MOVING S-SE
THROUGH THE GULF OF CALIFORNIA YESTERDAY HAS MOVE SOUTHEAST OF
THE GULF AND DISSIPATED IN THE VICINITY OF LAS ISLAS TRES MARIAS
MEXICO. THE PRESSURE GRADIENT BETWEEN THE HIGH AND LOWER
PRESSURES ALONG THE OLD FRONTAL REMNANTS AND THE ITCZ MAINTAINS
A BROAD ZONE OF 20-25 KT TRADE WINDS IN AN AREA GENERALLY W OF
122W AND N OF THE ITCZ. LARGE NW SWELL CONTINUES TO MOVE THROUGH
THE AREA AND IS MIXING WITH NE WIND WINDS IN THIS TRADE
WINDZONETO PRODUCE SEAS OF GENERALLY 10 TO 13 FT. THE LONG
PERIOD NW SWELL IS ALSO PRODUCING SEAS TO 8 TO 11 FT ACROSS THE
REMAINDER OF THE AREA WATERS N OF THE EQUATOR AND W OF 110W.
THIS AREA OF FRESH TO STRONG WINDS WILL GRADUALLY SHRINK AND
SHIFT SW OVER THE NEXT FEW DAYS...BECOMING CONFINED TO THE AREA
FROM 10N TO 24N AND W OF 120W BY THU NIGHT AS THE HIGH PRESSURE
WEAKENS AND DRIFTS SOUTHWARD TO ALONG 31N.  

THE PRESSURE GRADIENT BETWEEN HIGH PRESSURE OVER THE GREAT BASIN
AND A DEVELOPING SURFACE TROUGH ALONG THE COAST OF MEXICO IS
FORECAST TO TIGHTEN IN THE VICINITY OF THE GULF OF CALIFORNIA
TODAY AND ALLOW NW TO N WINDS TO INCREASE TO 20 TO 25 KTTHIS
AFTERNOON AND EVENING...AND CONTINUE THROUGH FRI AS THESE WINDS
SPREAD THE ENTIRE LENGTH OF THE GULF. GLOBAL MODELS SUGGESTS
WINDS COULD REACH 30 KT THU AFTERNOON AND NIGHT ACROSS CENTRAL
PORTIONS. ASSOCIATED SEAS WILL BUILD TO 8-10 FT ON THU.  
 
A WEAKENING EXTRATROPICAL CYCLONE OVER THE BERING SEA IS NOW
GENERATING A ROUND OF LONG PERIOD...20 TO 22 SECOND...NW SWELL
CURRENTLY MOVING INTO THE FAR NW PORTION OF THE FORECAST AREA.
THESE SWELLS WILL MOVE SE AND EXTEND FROM CENTRAL BAJA
CALIFORNIA TO 18N130W LATE TODAY AND FROM CABO CORRIENTES TO
05N125W BY LATE THU. THIS VERY LONG PERIOD SWELL MOVING THROUGH
THE AREA WATERS IN THE 6-9 FT RANGE WILL GENERATE VERY LARGE AND
POWERFUL SURF ACROSS THE REEFS...SHOALS AND COASTAL ZONES OF THE
MEXICO AND CENTRAL AMERICA DURING THE NEXT 48 HOURS. MARINE
INTERESTS FROM BAJA CALIFORNIA AND NEARBY ISLANDS SOUTHWARD
SHOULD REMAIN ALERT FOR THESE HAZARDOUS MARINE CONDITIONS AND
ONGOING DANGEROUS SURF CONDITIONS.   
 
$$
STRIPLING