000
AXPZ20 KNHC 180946
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC WED DEC 18 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 
0945 UTC.

...SPECIAL FEATURE...
 
GULF OF TEHUANTEPEC...GALE CONDITIONS ARE EXPECTED TO PERSIST
THROUGH THIS EVENING...THEN DIMINISH TO 20 TO 30 KT LATE TONIGHT
THROUGH MID MORNING ON THU. THE MAXIMUM SEAS ARE CURRENTLY AT
15 FT DOWNSTREAM OF THE GULF OF TEHUANTEPEC AND WILL GRADUALLY
SUBSIDE TO LESS THAN 8 FT THU EVENING.
 
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 

THE MONSOON TROUGH EXTENDS SW FROM THE COLOMBIAN COAST AT 07N78W 
TO 07N80W...THEN NW TO 09N85W...THEN SW AGAIN TO 06N95W...THEN
W TO 07N100W WHERE SCATTEROMETER WINDS INDICATE A TRANSITION TO 
AN ITCZ. THE ITCZ CONTINUES W TO 08N120W TO BEYOND 08N140W.

SCATTERED MODERATE ISOLATED STRONG CONVECTION IS ALONG THE MONSOON
TROUGH AND ITCZ WITHIN 120 NM EITHER SIDE OF A LINE FROM 07N78W TO
77N87W TO 08N112W TO 08N120W...THEN WIDENS TO WITHIN 180 NM OF LINE
FROM 08N120W TO 10N130W...THEN NARROWS WITHIN 30 NM OF LINE FROM 
10N135W TO 09N140W.
   
...DISCUSSION... 

GULF OF PAPAGAYO...NE-E WINDS WILL PULSE AT 20-25 KT DURING THE 
MAXIMUM NOCTURNAL DRAINAGE TONIGHT THROUGH FRI NIGHT...THEN MAX 
AT 15-20 KT ON SAT NIGHT. THE NE SWELL PROPAGATING SW FROM THE 
GULF OF PAPAGAYO WILL MIX WITH LONG PERIOD CROSS-EQUATORIAL 
SWELL...RESULTING IN COMBINED SEAS OF 6-9 FT AS FAR S AS 07N95W
ON THU AFTERNOON. EXPECT THE NOCTURNAL MAX TO ONLY REACH 15-20 
KT ON SAT NIGHT INTO SUN MORNING.  

A SURFACE RIDGE EXTENDS FROM 32N137W TO 16N105W WITH NE 15-20 KT
TRADES BETWEEN THE RIDGE AND ITCZ ACROSS THE WATERS W OF 117W.
LONG PERIOD NW SWELL IS MIXING WITH THE ASSOCIATED NE TRADE WIND
SWELL...AND ALSO WITH LONG PERIOD CROSS-EQUATORIAL SOUTHERLY 
SWELL...RESULTING IN COMBINED SEAS OF 6-9 FT WITHIN THE AREA
FROM 08-16N. THE GRADIENT WILL TIGHTEN TODAY WITH NE-E 15-25 KT
TRADES ENHANCED ACROSS THE DISCUSSION WATERS FROM 08-20N W OF 
130W WITH SEAS 6-9 FT TONIGHT.  

A COLD FRONT WILL APPROACH THE NORTHERN PORTION OF THE BAJA 
CALIFORNIA PENINSULA TONIGHT. STRENGTHENING HIGH PRESSURE 
IN THE WAKE OF THE FRONT WILL SUPPORT NORTHERLY 20-25 KT WINDS 
ACROSS THE DISCUSSION AREA N OF 25N ON THU NIGHT WITH SEAS BUILDING
TO 14 FT NEAR 30N124W. THE GRADIENT WILL BEGIN TO RELAX ON FRI
AS THE FRONT PASSES THROUGH THE GULF OF CALIFORNIA. THE NORTHERLY
WINDS WILL DIMINISH TO 15-20 KT ACROSS THE DISCUSSION AREA W OF
115W ON SAT.  
 
GULF OF CALIFORNIA...NW WINDS ARE CURRENTLY AT 10-15 KT ACROSS 
ENTIRE THE GULF WATERS ARE EXPECTED TO QUICKLY DIMINISH TO 5-10 
KT THIS MORNING...THEN BECOME SOUTHERLY LATER TODAY. THE 
SOUTHERLY WINDS WILL INCREASE OVER THE NORTHERN GULF WATERS LATE 
TONIGHT INTO EARLY THU AHEAD OF A PRE-FRONTAL TROUGH ARRIVING ON 
THU AFTERNOON FOLLOWED BY A COLD FRONT ON THU NIGHT. THE FRONT 
SHOULD REACH AS FAR S AS 27N ON FRI NIGHT ACCOMPANIED BY A SW-W-
NW 10-15 KT WIND SHIFT.  

$$
NELSON