000
AXPZ20 KNHC 162131
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC FRI NOV 16 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 08N82W TO 06N94W...WHERE IT TRANSITIONS TO 
ITCZ..CONTINUING TO 08N121W TO 07N126W TO 09N131W TO BEYOND 
08N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS FROM 
06N TO 10N BETWEEN 119W AND 122W. 

...DISCUSSION...
A 1020 MB HIGH PRESSURE IS CENTERED NEAR 27N119W. A 1005 MB LOW 
PRESSURE CENTER IS LOCATED N OF THE AREA NEAR 34N128W. THE 
ASSOCIATED COLD FRONT ENTERS THE FORECAST REGION NEAR 30N128W 
THEN CONTINUES S AND SW TO 23N140W. THE PRESSURE GRADIENT 
BETWEEN THE FEATURES IS MAINTAINING FRESH TO STRONG SW WINDS 
WITHIN 120 NM E OF THE COLD FRONT N OF 27N. THE LOW PRESSURE 
CENTER HAS STARTED TO LIFT OUT TO THE NE. THIS WILL DRAG THE 
ASSOCIATED COLD FRONT EASTWARD OVER THE NEXT DAY...BUT ALSO LEAD 
TO THE COLD FRONT DISSIPATING BY SUN MORNING. HIGH PRESSURE WILL 
THEN BUILD BACK ACROSS THE N PART OF THE AREA SUN. CURRENTLY... 
THE TRADEWINDS REMAIN BELOW 20 KT...BUT THEY ARE EXPECTED TO 
INCREASE TO 20-25 KT AS HIGH PRESSURE STARTS TO BUILD BACK 
ACROSS THE FORECAST WATERS ON SUN.  

LONG PERIOD NW SWELL ASSOCIATED WITH THE LOW PRESSURE SYSTEM IS 
PUSHING ACROSS THE NW PART OF THE REGION WITH COMBINED SEAS TO 
10 FT. THIS SET OF NW SWELLS WILL PROPAGATE S AND E ACROSS THE 
REGIONAL WATERS OVER THE NEXT COUPLE OF DAYS WITH SEAS SUBSIDING 
TO 8-9 FT. A NEW SET OF NW SWELLS WILL ENTER THE NW PART OF THE 
AREA WITH COMBINED SEAS REACHING 12 FT BY SUN MORNING. 

GAP WINDS...
A GALE WARNING CONTINUES ACROSS THE GULF OF TEHUANTEPEC. LATEST 
HIGH RESOLUTION ASCAT PASS REPORTED WINDS OF 30 KT OVER THIS 
AREA. WITH A 5 KT LOW BIAS...IT IS LIKELY THAT GALE FORCE WINDS 
ARE OCCURRING OVER THE AREA AND SUPPORTS THE CONTINUANCE OF THE 
GALE WARNING. WINDS WILL DIMINISH TO JUST BELOW GALE FORCE 
DURING THE AFTERNOON HOURS ON SAT. HOWEVER...DURING THE 
OVERNIGHT AND EARLY MORNING HOURS...THE ADDED COMPONENT OF 
NOCTURNAL DRAINAGE FLOW WILL PUSH WINDS BACK ABOVE GALE FORCE IN 
THE GULF OF TEHUANTEPEC. SO...WILL CONTINUE WITH THE GALE 
WARNING THROUGH SUN MORNING TO ACCOUNT FOR THIS PULSING OF WINDS 
TO GALE FORCE. 

WINDS ACROSS THE FAR WESTERN CARIBBEAN HAVE BECOME NORTHERLY... 
WITH LESS WIND NOT FUNNELING THROUGH THE GAP IN TOPOGRAPHY OVER 
NICARAGUA AND EXITING INTO THE EASTERN PACIFIC WATERS. PULSING 
OF NOCTURNAL WINDS IS THUS ONLY EXPECTED TO REACH AROUND 20 KT 
ACROSS THE GULF OF PAPAGAYO DURING THE NEXT FEW DAYS...AND SEAS 
THROUGH AND DOWNWIND OF THE GULF WILL REMAIN AROUND 6-7 FT.  

$$
GR