000
AXPZ20 KNHC 180215
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC FRI DEC 18 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0200 UTC.               
 
...SPECIAL FEATURE...

A STORM WARNING REMAINS IN EFFECT FOR THE GULF OF TEHUANTEPEC. A
COLD FRONT CURRENTLY MOVING ACROSS THE GULF OF MEXICO HAS
REACHED THE CENTRAL BAY OF CAMPECHE...AND IS ALLOWING NORTHERLY
WINDS BEHIND THE FRONT TO SPILL THROUGH THE ISTHMUS OF
TEHUANTEPEC AND ACROSS THE GULF OF TEHUANTEPEC. WINDS ACROSS
THESE PACIFIC WATERS ARE FORECAST TO REACH GALE FORCE LATE
TONIGHT INTO EARLY MORNING FRI...AND CONTINUE TO GRADUALLY
INCREASE AND EXPAND IN AREAL EXTENT ON FRI. A 1031 MB HIGH PRES
CENTER WILL MOVE INTO SOUTH-CENTRAL TEXAS BEHIND THE COLD FRONT
ON FRI PRODUCING A VERY STRONG PRES GRADIENT ACROSS THE ISTHMUS
OF TEHUANTEPEC AND FORCING A VERY STRONG AND BROAD GULF OF
TEHUANTEPEC GAP WIND EVENT FRI THROUGH THE UPCOMING WEEKEND.
WINDS ACROSS TEHUANTEPEC ARE EXPECTED TO REACH STORM FORCE...50-
55 KT...BY EARLY FRI EVENING AND LIKELY CONTINUE TO EARLY SAT
MORNING WITH THE ASSISTANCE OF THE NOCTURNAL DRAINAGE FLOW.
THEN...GALE FORCE WINDS ARE FORECAST TO PERSIST THROUGH SUN.
SEAS DOWNSTREAM OF THE GULF OF TEHUANTEPEC WILL BUILD TO 21-22
FT BY FRI EVENING. GLOBAL MODELS ALSO SUGGEST THAT THE WIDTH OF
THE GALE FORCE WINDS WILL BE UNUSUALLY BROAD FRI EVENING THROUGH
EARLY SAT...AND MAY EXTEND EASTWARD ACROSS THE TEHUANTEPEC AREA
TO NEAR 93.5W ACROSS THE OFFSHORE WATERS...AND TO PUERTO ARISTA
ALONG THE COAST OF MEXICO. 
 
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...            

A SURFACE TROUGH EXTENDS FROM 06N85W TO 07N103W TO 06N110W.
ITCZ AXIS EXTENDS FROM 06N110W TO 06N115W TO 03N127W.
NO SIGNIFICANT CONVECTION IS NOTED. 
 
...DISCUSSION...

A SURFACE TROUGH EXTENDS PARALLEL TO THE COAST FROM NW MEXICO TO
NEAR MAZATLAN...BETWEEN 1029 MB HIGH PRES OVER THE EASTERN
PACIFIC AND ANOTHER 1029 MB HIGH PRES CENTERED TO THE NORTH OVER
THE GREAT BASIN. THIS HAS TIGHTENED THE PRES GRADIENT ENOUGH TO
SUPPORT STRONG NW WINDS ALONG THE LENGTH OF THE GULF OF
CALIFORNIA AS WELL AS OFF THE SOUTHERN COAST OF BAJA CALIFORNIA
SUR. SEAS ARE REACHING 8 FT IN THE GULF OF  THE SUBTROPICAL
RIDGE OVER THE EASTERN PACIFIC WILL WEAKEN AHEAD OF AN ADVANCING
COLD FRONT THROUGH EARLY FRI. THIS WILL ALLOW THE STRONG WINDS
TO GRADUALLY TAPER OFF THROUGH THE NEXT 24 HOURS. LOOKING
AHEAD...THE COLD FRONT WILL MOVE INTO BAJA CALIFORNIA NORTE BY
EARLY SUN THEN DISSIPATE. 

LONG PERIOD NW SWELL AT 20 TO 22 SECONDS CONTINUES TO SPREAD
SE ACROSS THE FORECAST WATERS MAINLY N OF 20N AND JUST OFF
THE WATERS FROM CABO CORRIENTES TO NEAR 05N125W...AND WILL
REACH FROM NEAR ACAPULCO MEXICO TO THE EQUATOR EARLY FRI. THIS
VERY LONG PERIOD SWELL MOVING THROUGH THE FORECAST WATERS
WILL GENERATE VERY LARGE AND POWERFUL SURF ACROSS THE
REEFS...SHOALS AND COASTAL ZONES OF MEXICO AND CENTRAL AMERICA
DURING THE NEXT48 HOURS. MARINE INTERESTS FROM BAJA CALIFORNIA
AND NEARBY ISLANDS SOUTHWARD SHOULD REMAIN ALERT FOR THESE
HAZARDOUS MARINE CONDITIONS AND ONGOING DANGEROUS SURF
CONDITIONS. AREAS OF CONFUSED SEAS COVER THE AREA FROM 05N TO
14NBETWEEN 92W AND 105W WHERE THE LONGER PERIOD NW SWELL MIXES
WITH SHORTER PERIOD NE SWELL PROPAGATING OUT OF TEHUANTEPEC.

HIGH PRES OVER THE UNITED STATES WILL SUPPORT STRONG GAP WINDS
THROUGH THE GULF OF PAPAGAYO LATE FRI AND SAT. 

ELSEWHERE...THE 1029 MB SUBTROPICAL HIGH OVER THE EASTERN
PACIFIC WILL SUPPORT STRONG TRADES THROUGH TODAY FROM 11N TO 22N
W OF 125W. THESE TRADE WINDS WILL DIMINISH FRI AS THE HIGH
WEAKENS...THEN STRENGTHEN AGAIN BY SAT AS HIGH PRES BUILDS
BEHIND THE COLD FRONT.

$$ 
CHRISTENSEN