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Eastern Pacific Tropical Weather Discussion (Text)

000
AXPZ20 KNHC 200920
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC THU DEC 19 2013

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.

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

MONSOON TROUGH AXIS EXTENDS FROM 08N78W TO 07N90W TO 06N99W... 
WHERE IT TRANSITIONS TO THE ITCZ TO 08N115W TO 09N127W TO 
09N140W. SCATTERED MODERATE FROM 11N TO 13N BETWEEN 123W AND 
128W...AND FROM 09N TO 12N BETWEEN 128W AND 132W.  

...DISCUSSION... 

A FAST MOVING COLD FRONT HAS PUSHED INTO THE N WATERS AND NOW 
EXTENDS NORTHERN BAJA CALIFORNIA NEAR 30N115W TO 25N125W TO 
26N140W. A LARGE AND STRONG AREA OF HIGH PRES...ANALYZED 1036 MB 
NEAR 40N139W ON THE 0600 UTC SURFACE MAP...IS NOTED IN THE WAKE 
OF FRONT. THE ASSOCIATED TIGHT PRES GRADIENT IS SUPPORTING NW TO 
N WINDS OF 20-30 KT N OF THE FRONT WITH SEAS OF 8-12 FT E OF 
120W. MUCH LARGER SEAS OF 10-16 FT IN NW SWELL ARE BEHIND THE 
FRONT BETWEEN 120W AND 130W WITH SEAS OF 8 TO 11 FT W OF 130W. 
THE FRONT IS FORECAST TO DISSIPATE IN ABOUT 24 HOURS WITH A 
FRONTAL TROUGH MOVING ACROSS NW MEXICO LATE FRI. THE NW TO N 
WINDS BEHIND THE FRONT WILL GRADUALLY DIMINISH THROUGH SAT AS 
THE PRES GRADIENT ATTRIBUTED TO THE STRONG HIGH PRES N OF THE 
AREA SLACKENS SOME. LARGE NLY SWELLS BEHIND THE FRONT WILL 
SLOWLY SUBSIDE TO 10-12 FT BY FRI NIGHT...AND TO 8-11 FT BY SAT 
NIGHT. 

A STRONG SURFACE RIDGE EXTENDS INTO THE AREA FROM THE ABOVE 
MENTIONED 1036 MB HIGH PRES. PRES GRADIENT BETWEEN THE HIGH AND 
LOWER PRESSURE ALONG THE ITCZ IS PRODUCING FRESH TO STRONG TRADE 
WINDS BETWEEN THE RIDGE AND ITCZ...PARTICULARLY FROM 10N TO 25N 
W OF 130W. THE GRADIENT WILL RELAX SOME THROUGH SAT NIGHT AS 
HIGH PRES MOVES S AND SLIGHTLY WEAKENS.

LONG PERIOD NW SWELLS...WAVE PERIODS BETWEEN 20-22 SEC...WILL 
REACH THE FAR NW CORNER LATE TODAY AND PROPAGATE ACROSS THE NW 
WATERS ON SAT...REACHING THE REMAINDER OF THE WESTERN PART OF 
THE FORECAST AREA SAT NIGHT. MOST OF THE DISCUSSION AREA W OF 
115W WILL BE UNDER THE INFLUENCE OF THIS SWELL EVENT BY SUN 
NIGHT. 

GULF OF TEHUANTEPEC...THE RECENT LONG DURATION GALE EVENT ACROSS 
THE GULF OF TEHUANTEPEC ENDED. RECENT SCATTEROMETER DATA ONLY 
SHOW NORTHERLY WINDS OF 10-15 KT ACROSS THIS AREA. THE NEXT GAP 
WIND EVENT IS FORECAST TO BEGIN LATE SUN NIGHT INTO MON WITH 
WINDS REACHING GALE FORCE AGAIN. THIS NEXT EVENT WILL LIKELY BE 
ANOTHER STRONG ONE AS MARINE GUIDANCE INDICATES THAT IT WILL 
PERSIST THROUGH THE MIDDLE OF NEXT WEEK.

GULF OF PAPAGAYO...NE-E WINDS OF 20-25 KT WILL CONTINUE TO BLOW 
DOWNSTREAM OF PAPAGAYO OVER THE NEXT 48 HOURS. THE WINDS ARE 
GREATEST DURING THE OVERNIGHT AND EARLY MORNING HOURS WITH THE 
ASSISTANCE OF THE NOCTURNAL DRAINAGE FLOW...AND SOME ADDED 
ENHANCEMENT FROM THE EASTERLY GRADIENT FLOW FROM THE CARIBBEAN 
SEA. 

GULF OF CALIFORNIA...THE LATEST ASCAT PASS SHOWED SW WINDS OF 
20-25 KT OVER THE EXTREME NRN PORTION OF THE GULF AHEAD OF THE 
AFOREMENTIONED COLD FRONT. THESE WINDS WILL BEGIN TO DIMINISH 
TODAY AS THE FRONT WEAKENS. HIGH PRES WILL BUILD BACK INTO THE 
REGION THIS WEEKEND FROM THE NW...AND INCREASE THE PRES GRADIENT 
TO SUPPORT NW WINDS OF 15-20 KT ACROSS THE ENTIRE GULF OF 
CALIFORNIA ON SUN EVENING.

$$
GR