000
AXPZ20 KNHC 200939
TWDEP 

TROPICAL WEATHER DISCUSSION                                   
NWS NATIONAL HURRICANE CENTER MIAMI FL                       
1005 UTC TUE JAN 20 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
0900 UTC.               
 
...SPECIAL FEATURES... 

GULF OF TEHUANTEPEC GALE WARNING...THE LATEST HIGH RESOLUTION
ASCAT-B PROVIDED OBSERVATIONS OF GALE FORCE WINDS ACROSS THE
GULF AND DOWNWIND TO NEAR 14N96W. THE PRESSURE GRADIENT BETWEEN
STRONG HIGH PRESSURE OVER EASTERN MEXICO AND LOWER PRESSURE
ASSOCIATED WITH A SURFACE TROUGH OVER THE FAR EASTERN NORTH
PACIFIC IS MAINTAINING THESE GALE FORCE WINDS. THE HIGH PRESSURE
WILL SHIFT NE AND WINDS OVER THE SW GULF OF MEXICO WILL VEER TO
THE E AND SE TODAY. THIS WILL DECREASE WINDS FUNNELING INTO THE
GULF OF TEHUANTEPEC AND WINDS WILL DIMINISH BELOW GALE FORCE BY
THIS AFTERNOON. WINDS AND SEAS WILL CONTINUE TO DIMINISH DURING
THE DAY TODAY. BY TONIGHT...EXPECT NORTHERLY WINDS OF 20-25 KT
WITH THE ASSISTANCE OF THE NOCTURNAL DRAINAGE FLOW AND SEAS TO
AROUND 8 FT. NE TO E SWELL ASSOCIATED WITH THIS EVENT COMBINED
WITH A GALE WIND EVENT OVER THE GULF OF PAPAGAYO IS MIXING WITH
LONG PERIOD NW SWELL TO PRODUCE A VERY LARGE AREA OF SEAS 8 FT
OR GREATER THAT EXTENDS SW TO BEYOND 100W.

GULF OF PAPAGAYO GALE WARNING...A TIGHT PRESSURE GRADIENT ACROSS
CENTRAL AMERICA IS SUPPORTING MINIMAL GALE FORCE WINDS IN THE
GULF OF PAPAGAYO AND FRESH TO STRONG WINDS ACROSS A LARGE
PORTION OF THE AREA FROM 08N TO 12N E OF 92W. WINDS ARE EXPECTED
TO DIMINISH BELOW GALE FORCE THIS AFTERNOON...BUT THE AREA OF
FRESH TO STRONG WINDS WILL EXTEND FARTHER W REACHING 96W/97W.
EXPECT PULSING WINDS OF 20-25 KT ACROSS THIS GULF TONIGHT...AND
THU NIGHT.  

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

THE ITCZ AXIS EXTENDS FROM 05N87W TO 04N104W TO 04N114W TO
05N130W TO 01N140W. A COUPLE OF WEAK TROUGHS ARE EMBEDDED WITHIN
THE ITCZ...ONE NEAR 108W AND THE OTHER NEAR 118W. SCATTERED
MODERATE CONVECTION IS NOTED FROM 05N TO 09N BETWEEN 102W AND
108W. NO SIGNIFICANT CONVECTION ELSEWHERE.
 
...DISCUSSION...

A 1024 MB HIGH PRESSURE CENTERED NEAR 27N126W EXTENDS A RIDGE SE
TO NEAR THE REVILLAGIGEDO ISLANDS. THE PRESSURE GRADIENT BETWEEN
THE RIDGE AND LOWER PRESSURE ASSOCIATED WITH THE ITCZ IS
MAINTAINING FRESH TRADES FROM 06N-15N W OF 128W. THE AREA OF
HIGH PRESSURE WILL WEAKEN OVER THE NEXT 24 HOURS AND TRADES N OF
THE ITCZ OVER THE WESTERN WATERS WILL DIMINISH TO 20 KT OR LESS
BY THURSDAY. A COLD FRONT WILL MOVE INTO THE NW WATERS TONIGHT.
SW WINDS AHEAD OF THE FRONT WILL INCREASE TO NEAR GALE FORCE
OVER THE FAR NW WATERS LATER TODAY. THE FRONT WILL PROPAGATE
INTO THE AREA AND REACH FROM 30N134W TO 26N140W BY THU MORNING
AND FROM 30N131W TO 23N140W BY THU EVENING. THIS FRONT WILL
USHER IN A FRESH SET OF NW SWELLS WITH COMBINED SEAS REACHING
NEAR 18-20 FT BY THU MORNING IN THE FAR NW WATERS. 

FRESH TO STRONG N-NE WINDS FUNNELING FROM THE SW CARIBBEAN
THROUGH THE GULF OF PANAMA ARE EXTENDING DOWNSTREAM TO NEAR 04N
WITH SEAS TO 8-10 FT PER AN ALTIMETER PASS. WINDS ARE EXPECTED
TO DIMINISH TO 20 KT THIS EVENING WITH SEAS SUBSIDING TO 6-7 FT
AS THE PRES GRADIENT IN THE W CARIBBEAN RELAXES. NW WINDS ARE
EXPECTED TO INCREASE TO 20-25 KT IN THE CENTRAL GULF OF
CALIFORNIA ON THU...THEN DIMINISH ON FRI.

NE SWELL GENERATED BY THE COMBINED ONGOING GALE WIND EVENTS IN
TEHUANTEPEC AND PAPAGAYO ARE MERGING DOWNSTREAM TO PRODUCE A
VERY LARGE AREA OF SEAS 8 FT OR MORE EXTENDING BEYOND 100W.
LARGE LONG PERIOD NW SWELL CONTINUES TO PROPAGATE ACROSS THE
FORECAST AREA...WITH THE LEADING EDGE OF THIS SWELL EVENT
REACHING WATERS E OF 100W AND MIXING WITH CROSS EQUATORIAL SW
SWELL AND THE NE SWELL GENERATED IN THE GAP WIND REGIONS. AS A
RESULT...SEAS 8 FT OR GREATER DOMINATES NEARLY ALL OF THE
FORECAST WATERS. THE MAIN EXCEPTIONS ARE GULF OF CALIFORNIA AND
LEE OF GALAPAGOS ISLANDS. 

LOOKING AHEAD...MOST OF THE GLOBAL MODELS CONTINUE TO SUGGEST A
GALE TO MINIMAL STORM FORCE WIND EVENT ACROSS THE GULF OF
TEHUANTEPEC ON FRI. THIS WILL BE ASSOCIATED WITH A STRONG COLD
FRONT MOVING ACROSS THE WESTERN GULF OF MEXICO. WINDS ARE
EXPECTED TO REACH MINIMAL GALE FORCE BY EARLY FRI MORNING...THEN
SUDDENLY INCREASE TO 40-45 KT BY FRI AFTERNOON AS A STRONG HIGH
PRES OF 1030 MB EXTENDS A RIDGE SOUTHWARD FROM TEXAS ALONG THE
MEXICAN COASTAL PLAINS. A VERY TIGHT PRES GRADIENT ACROSS THE
ISTHMUS OF TEHUANTEPEC IS FORECAST TO SUPPORT THESE VERY STRONG
WINDS THAT MAY REACH NEAR 50 KT BY FRI EVENING OR NIGHT. 

$$ 
GR