054  
AXPZ20 KNHC 091529  
TWDEP  
 
TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL  
1414 UTC THU NOV 9 2017  
 
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  
1500 UTC.  
   
..SPECIAL FEATURES
 
 
GULF OF TEHUANTEPEC GALE WARNING...HIGH PRESSURE SURGING SOUTHWARD  
BEHIND A COLD FRONT MOVING ACROSS THE WESTERN GULF OF MEXICO  
WILL PUSH A COOLER AIR MASS TOWARDS THE EASTERN SLOPES OF THE  
SIERRA ORIENTAL MOUNTAINS ALONG EASTERN MEXICO. THIS WILL FURTHER  
INTENSIFY THE PRESSURE GRADIENT ALREADY IN PLACE ALLOWING FOR  
NORTHERLY WINDS TO INCREASE TO MINIMAL GALE FORCE ACROSS THE  
GULF OF TEHUANTEPEC BY EARLY THIS AFTERNOON. SEAS ARE EXPECTED TO  
BUILD TO THE RANGE OF 10-15 FT WITH THESE GALE CONDITIONS. A  
GALE WARNING IS ALREADY IN EFFECT FOR THE GULF OF TEHUANTEPEC  
THROUGH 48 HOURS. WINDS MAY BRIEFLY DIMINISH JUST BELOW GALE  
FORCE DURING THE AFTERNOON HOURS AFTER TODAY. MODEL GUIDANCE  
SUGGESTS THAT THIS EVENT WILL LAST THROUGH EARLY NEXT WEEK, WITH  
WINDS INCREASING TO 35-40 KT SUN NIGHT THROUGH MONDAY NIGHT.  
DURING THIS TIME PERIOD, SEAS ARE FORECAST TO BUILD TO 14-16 FT.  
   
..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH
 
 
THE MONSOON TROUGH AXIS EXTENDS FROM 10N84W TO 09N100W TO 1010 MB  
LOW PRESSURE NEAR 10N122W TO 09N140W. SCATTERED MODERATE CONVECTION  
IS N OF 06N E OF 82W...INCLUDING THE GULF OF PANAMA, AND FROM 07N  
TO 10N BETWEEN 82W AND 87W. SCATTERED MODERATE TO ISOLATED STRONG  
CONVECTION IS FROM 08N TO 10N BETWEEN 102W AND 107W, AND FROM 08.5N  
TO 11N BETWEEN 120W AND 124W IN ASSOCIATION WITH THE ABOVE MENTIONED  
LOW. SCATTERED MODERATE CONVECTION IS FROM 10N TO 12N BETWEEN 124W  
AND 128W.  
   
..DISCUSSION
 
 
OFFSHORE WATERS WITHIN 250 NM OF MEXICO...  
 
PLEASE SEE THE SPECIAL FEATURES SECTION FOR INFORMATION ON A GULF  
OF TEHUANTEPEC GALE WARNING.  
 
A RIDGE WILL DOMINATE THE WATERS W OF BAJA CALIFORNIA THROUGH THE  
REST OF THE WEEK, WHILE A TROUGH WILL MEANDER BETWEEN THE COAST  
OF NW MEXICO AND THE GULF OF CALIFORNIA. MODERATE TO LOCALLY  
FRESH NW TO N FLOW WILL PREVAIL ACROSS THE WATERS W OF BAJA  
CALIFORNIA, INCREASING TO FRESH TO LOCALLY STRONG OFFSHORE OF  
THE NORTHERN WATERS THIS EVENING THROUGH FRI AS THE PRESSURE  
GRADIENT SLIGHTLY TIGHTENS BETWEEN A HIGH PRESSURE CENTER OVER  
THE NORTHERN FORECAST WATERS AND THE AFOREMENTIONED TROUGH. A  
COLD FRONT IS EXPECTED TO WEAKEN BEFORE REACHING THE AREA ON FRI,  
BUT THE ASSOCIATED LONG PERIOD NW SWELL INDUCING SEAS IN THE  
RANGE OF 8 TO 10 FT WILL PROPAGATE SOUTHEASTWARD ACROSS THE  
WATERS N OF 23N AND TO THE W OF BAJA CALIFORNIA ON FRI, THEN  
SPREAD SOUTHWARD THROUGH ALL OF THE WATERS W OF BAJA ON SAT,  
SUBSIDING TO LESS THAN 8 FT BY EARLY SUN. LOOKING AHEAD, THE  
PRESSURE GRADIENT W OF BAJA CALIFORNIA WILL TIGHTEN EVEN MORE  
MON THROUGH TUE, WITH INCREASING OF 20-25 KT AND BUILDING SEAS  
OF 8 TO 9 FT ACROSS THE WATERS N OF 24N OR 25N.  
 
GULF OF CALIFORNIA: A RELATIVELY TIGHT PRESSURE GRADIENT IS  
SUPPORTING MODERATE TO FRESH NW FLOW ACROSS THE CENTRAL AND  
SOUTHERN GULF, WITH GENTLE TO MODERATE NW FLOW TO THE N. SEAS ARE  
2 FT OR LESS IN THE NORTHERN GULF, AND 4 TO 6 FT ELSEWHERE. THE  
GRADIENT WILL SLACKEN WITH WINDS DIMINISHING TO LIGHT TO GENTLE  
THROUGHOUT FOR THE END OF THE WEEK THROUGH SAT, WITH SEAS  
SUBSIDING TO 2 FT OR LESS, EXCEPT 4 TO 6 FT NEAR THE ENTRANCE OF  
THE GULF. THE PRESSURE GRADIENT WILL TIGHTEN BACK A BIT FOR THE  
END OF THE WEEKEND INTO EARLY NEXT WEEK WITH GENTLE TO MODERATE  
NW WINDS ACROSS THE ENTIRE GULF.  
 
ELSEWHERE, MAINLY GENTLE TO MODERATE NW FLOW AND 4 TO 6 FT SEAS  
WILL PREVAIL FOR THE NEXT SEVERAL DAYS.  
 
OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND  
WITHIN 750 NM OF ECUADOR...  
 
GULF OF PAPAGAYO: NOCTURNAL DRAINAGE FLOW WILL SUPPORT PULSING  
MODERATE TO FRESH WINDS DURING THE OVERNIGHT HOURS FOR THE NEXT  
SEVERAL DAYS, WITH SEAS OCCASIONALLY BUILDING TO 5 OR 6 FT  
DOWNSTREAM OF THE GULF NEAR 11N87W.  
 
LIGHT AND VARIABLE WINDS AND 4 TO 6 FT SEAS ARE EXPECTED ELSEWHERE  
TO THE N OF 09N, WHILE MODERATE TO LOCALLY FRESH SOUTHERLY WINDS  
AND 5 TO 7 FT SEAS ARE FORECAST S OF 09N THROUGH THE NEXT SEVERAL  
DAYS.  
 
REMAINDER OF THE AREA...  
 
A COLD FRONT IS MOVING ACROSS THE NORTHERN FORECAST WATERS AND  
EXTENDS FROM 30N130W TO 27N140W. A NEW SET OF LONG PERIOD NW  
SWELL FOLLOWS THE FRONT, WITH SEAS UP TO 12 FT OR 13 FT. THIS  
SWELL EVENT WILL PROPAGATE SE ACROSS THE AREA REACHING THE WATERS  
W OF BAJA CALIFORNIA AS PREVIOUSLY MENTIONED. THE FRONT WILL  
WEAKEN AND EVENTUALLY STALL FROM 30N128W TO 26N140W EARLY ON FRI.  
SEAS OF 8 FT OR GREATER WILL COVER THE WATERS N OF 15N W OF 115W  
BY FRI EVENING, THEN BEGIN TO SUBSIDE TO NEAR 8 FT THROUGHOUT  
THE WATERS BY SUN EVENING.  
 
A TRANSIENT AND WEAK LOW PRESSURE REMAINS ALONG THE MONSOON  
TROUGH NEAR 10N122W, AND WILL CONTINUE TO MOVE WESTWARD THROUGH  
THE UPCOMING WEEKEND AND INTO EARLY NEXT WEEK. MODEL GUIDANCE  
INDICATES A TIGHTENING PRESSURE GRADIENT BETWEEN THE LOW AND  
AND BUILDING HIGH PRESSURE TO THE N DURING THE WEEKEND INTO EARLY  
NEXT WEEK. THIS MAY ALLOW FOR TRADES TO INCREASE TO FRESH TO STRONG  
ACROSS THE WATERS S OF 20N AND N OF THE MONSOON TROUGH/ITCZ,  
SUPPORTING FRESH SEAS OF 8 TO 10 FT.  
 

 
GR  
 
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