000
AXPZ20 KNHC 172133
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SAT NOV 17 2012

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 
2100 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
MONSOON TROUGH FROM 08.5N84W TO 06N92W WHERE IT TRANSITIONS TO 
ITCZ...CONTINUING TO 06N115W TO 07N128W TO BEYOND 07N140W. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION WITHIN 90 NM N OF 
AXIS BETWEEN 120W AND 124W...AND FROM 06N TO 10N BETWEEN 124W 
AND 130W.

...DISCUSSION...
A WEAKENING COLD FRONT ENTERS THE FORECAST AREA NEAR 30N121W AND 
EXTENDS SW TO 25N128W. THE COLD FRONT WILL DISSIPATE BY SUN. 
HIGH PRES IN THE WAKE OF THE FRONT WILL BUILD ACROSS THE N PART 
OF THE AREA. THIS WILL TIGHTEN THE PRESSURE GRADIENT BETWEEN THE 
RIDGE AND THE ITCZ RESULTING IN AN INCREASE IN THE TRADE WIND 
FLOW...ESPECIALLY BETWEEN 10N AND 20N W OF 130W...BY TONIGHT. 
EXPECT NE TO E WINDS OF 20 TO 25 KT WITH BUILDING SEAS OF 8 TO 
10 FT. A SURFACE TROUGH...EMBEDDED IN THE ITCZ...EXTENDS FROM 
11N127W TO 07N130W. THE 1754 UTC ASCAT PASS SHOWED NE WINDS OF 
20 TO 25 KT AHEAD OF THE TROUGH AXIS. THIS FEATURE IS PRODUCING 
SOME SHOWER AND TSTM ACTIVITY FROM 06N TO 10N BETWEEN 124W AND 
130W.

LONG PERIOD NW SWELL CONTINUES TO PUSH ACROSS THE NW PART OF THE 
REGION WITH COMBINED SEAS TO 9 FT. THIS SET OF NW SWELLS WILL 
CONTINUE TO PROPAGATE S AND E ACROSS THE REGIONAL WATERS OVER 
THE NEXT DAY WITH SEAS CONTINUING TO SLOWLY SUBSIDE. ADDITIONAL 
PULSES OF NW SWELLS WILL ENTER THE NW PART OF THE AREA BY EARLY 
SUN...WITH SEA HEIGHTS REACHING 12 FT OVER THE FAR NW PART OF 
THE AREA. 

GAP WINDS...
PERSISTENT NORTHERLY WINDS 20-30 KT CONTINUE TO BE ENHANCED BY 
NOCTURNAL DRAINAGE FLOW ACROSS THE GULF OF TEHUANTEPEC... 
REACHING MINIMAL GALE FORCE ROUGHLY BETWEEN 0600 AND 1200 UTC. 
THIS GAP WIND FLOW IS EXPECTED TO PERSIST FOR SEVERAL MORE DAYS. 
THE ISSUANCE OF THE HIGH SEAS FORECAST...HSFEP2/FZPN03 KNHC... 
AT 1800 UTC REFLECTS THIS ON AND OFF MINIMAL GALE FORCE WIND 
EVENT. 

PULSING OF NOCTURNAL WINDS ARE ALSO EXPECTED ACROSS THE GULF OF 
PAPAGAYO REACHING AROUND 20 KT FROM 0600 TO 1200 UTC...WITH SEAS 
OF 6-7 FT THROUGH AND DOWNWIND OF THE GULF.  

$$
GR