458  
AXPZ20 KNHC 072205  
TWDEP  
 
TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL  
2123 UTC TUE NOV 7 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH  
2145 UTC.  
   
..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH
 
 
 
THE MONSOON TROUGH AXIS EXTENDS FROM 10N85W TO 09N90W TO 09N100W  
TO 11N110W TO LOW PRESSURE NEAR 10N116W 1012 MB TO 09N140W.  
SCATTERED MODERATE ISOLATED STRONG CONVECTION WITHIN 60 NM S OF  
AXIS BETWEEN 116W AND 118W, AND WITHIN 30 NM OF AXIS BETWEEN 88W  
AND 92W. SCATTERED MODERATE CONVECTION IS WITHIN 60 NM OF AXIS  
BETWEEN 124W AND 131W.  
   
..DISCUSSION
 
 
OFFSHORE WATERS WITHIN 250 NM OF MEXICO...  
 
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 STRONG OFFSHORE OF THE  
NORTHERN WATERS THU NIGHT THROUGH FRI. A COLD FRONT IS EXPECTED  
TO WEAKEN BEFORE REACHING THE AREA ON FRIDAY, 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 FRIDAY, THEN SPREAD SOUTHWARD  
THROUGH ALL THE WATERS W OF BAJA ON SATURDAY WHILE SUBSIDING  
SLIGHTLY.  
 
GULF OF TEHUANTEPEC: PULSES OF STRONG NORTHERLY DRAINAGE FLOW,  
WITH SEAS BUILDING TO MAXIMUM OF ABOUT 10 FT, ARE FORECAST  
THROUGH EARLY THURSDAY. THESE NORTHERLY WINDS ARE THEN EXPECTED  
TO INCREASE TO NEAR GALE FORCE BY LATE THURSDAY MORNING INTO  
EARLY THURSDAY AFTERNOON AND TO MINIMAL GALE FORCE BY LATE  
THURSDAY AFTERNOON OR EVENING. GALE FORCE WINDS ARE FORECAST TO  
PERSIST THROUGH EARLY FRIDAY MORNING, WITH SEAS THEN BUILDING UP  
TO 10 OR 14 FT. AS THE TIGHT PRESSURE GRADIENT OVER SOUTHEASTERN  
MEXICO SLACKENS DURING FRIDAY AFTERNOON, THE GALE FORCE WINDS  
WILL THEN DIMINISH TO BELOW GALE FORCE AND ASSOCIATED SEAS WILL  
SUBSIDE SOME. THE PRESSURE GRADIENT WILL TIGHTEN AGAIN BY FRIDAY  
EVENING USHERING IN ANOTHER ROUND OF NORTHERLY GALE FORCE THROUGH  
THE ISTHMUS OF TEHUANTEPEC AND ACROSS THE GULF. PRESENTLY, IT  
APPEARS BASED ON LATEST NAM/GFS MODEL GUIDANCE THAT THIS NEXT  
EPISODE OF GALE FORCE WINDS WILL BE SMALL IN COVERAGE.  
 
GULF OF CALIFORNIA: MODERATE TO LOCALLY FRESH NW WINDS WILL  
CONTINUE THROUGH TONIGHT. THE PRESSURE GRADIENT WILL TIGHTEN A  
LITTLE RESULTING IN A NARROW SWATH OF FRESH TO STRONG NW WINDS  
FROM 25N TO 28N ON WEDNESDAY. THE PRESSURE GRADIENT WILL RELAX  
WITH MODERATE NW FLOW ONLY TO THE S OF 26N BY THURSDAY EVENING.  
MAINLY LIGHT AND VARIABLE WINDS AND SEAS OF 2 FT OR LESS WILL  
THEN PREVAIL FOR THE END OF THE WEEK INTO THE UPCOMING WEEKEND.  
 
OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND  
WITHIN 750 NM OF ECUADOR...  
 
GULF OF PAPAGAYO: PULSING MODERATE TO LOCALLY FRESH N TO NE  
WINDS ARE FORECAST DURING THE OVERNIGHT HOURS THROUGH WEDNESDAY,  
WITH SEAS BUILDING TO 5 OR 6 FT DOWNSTREAM 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 REMAINDER OF THE WEEK.  
 
REMAINDER OF THE AREA...  
 
WATER VAPOR IMAGERY REVEALS A LONGWAVE TROUGH THAT STRETCHES FROM  
SOUTHERN CALIFORNIA SOUTHWESTWARD TO 32N126W TO 25N135W AND TO AN  
ELONGATED UPPER LOW LOCATED AT 16N140W. A VERY PRONOUNCED JET  
STREAM BRANCH ALONG THE TROUGH IS ATTENDANT BY STRONG SW WINDS  
THAT ARE ADVECTING ABUNDANT OVERCAST TO BROKEN MID AND HIGH  
LEVEL CLOUDS NORTHEASTWARD TOWARDS NORTHERN AND CENTRAL BAJA  
CALIFORNIA AS WELL AS EXTREME SOUTHERN CALIFORNIA. THESE CLOUDS  
EXTENT WITHIN 480 NM TO THE SE OF THE TROUGH AXIS. ISOLATED  
SHOWERS ARE POSSIBLE UNDERNEATH MOST OF THESE CLOUDS.  
 
AT THE SURFACE, A 1016 MB LOW IS ANALYZED NEAR 31N126W, WITH A  
DISSIPATING OCCLUDED FRONT ENTERING THE FORECAST AREA NEAR  
30N123W AND EXTENDING SSW TO 26N124W TO 20N130W. THE LOW IS  
FORECAST TO CONTINUE TO PULL NORTHEASTWARD AWAY FROM THE  
DISCUSSION AREA THROUGH WEDNESDAY. THE FRONT IS EXPECTED TO  
GRADUALLY DISSIPATE BY WEDNESDAY EVENING. ANOTHER COLD FRONT IS  
FORECAST TO REACH A POSITION FROM NEAR 32N138W TO 29.5N140W BY  
EARLY WEDNESDAY AFTERNOON FOLLOWED BY A NEW SET OF LONG PERIOD NW  
SWELL. THE FRONT WILL THEN REACH FROM NEAR 32N131W TO 28N135W  
AND DISSIPATING STATIONARY TO 28N140W. THE ASSOCIATED LONG PERIOD  
NW SWELL, WITH RESULTANT SEAS OF 8 TO 13 FT WILL PROPAGATE  
SOUTHEASTWARD THROUGH THE NORTHERN FORECAST WATERS WHILE  
DECAYING. SEAS OF 8 FT OR GREATER WILL COVER THE WATERS N OF 14N  
W OF 125W AND N OF A LINE FROM 21N119W TO 14N125W BY FRIDAY  
AFTERNOON, THEN BEGIN TO SUBSIDE TO NEAR 8 FT BEYOND FRIDAY AS  
THE SWELL AREA SHRINKS.  
 

 
AGUIRRE  
 
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