000
AXPZ20 KNHC 041533
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SAT DEC 04 2010

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1515 UTC.

...ITCZ...

INTERTROPICAL CONVERGENCE ZONE AXIS IS ALONG 08N83W TO WEAK LOW 
PRES NEAR 07N100W TO 10N118W TO 08N140W. SCATTERED MODERATE 
WITHIN 90 NM N OF AXIS W OF 132W. 

...DISCUSSION...
A SHARP LONGWAVE TROUGH COVERS THE NW PORTION OF THE AREA 
GENERALLY N OF 15N W OF 120W. THERE ARE A COUPLE OF SIGNIFICANT 
SHORTWAVE TROUGHS ROTATING THROUGH THE MEAN TROUGH AXIS. THE 
FIRST SHORTWAVE EXTENDS FROM THE N COAST OF CALIFORNIA SSEWD 
THROUGH 30N124W TO 22N121W AND WAS TURNING NE AT 20 KT. THIS 
TROUGH SUPPORTS A COLD FRONT THAT EXTENDS FROM 30N125W TO 
24N130W TO 17N140W. NW TO N WINDS OF 20 KT ARE NOTED W OF FRONT 
WHICH VEERED TO THE N TO NE S OF 20N. SEAS ARE RANGING FROM 9 TO 
12 FT IN NW SWELL IN THE WAKE OF THE FRONT. 

A SECOND SHORTWAVE TROUGH IS DIVING DOWN THE BACKSIDE OF THE 
BROADER TROUGH AND EXTENDS FROM A MID LEVEL CYCLONE NEAR 36N139W 
THROUGH 30N137W TO 26N140W. THE TROUGH/MID LEVEL CYCLONE WILL 
LEND SUPPORT TO A DEEPENING LOW PRES THAT IS FORECAST TO DIVE 
SOUTH TO NEAR 34N132W EARLY SUN AS A 1002 MB LOW. THE PROXIMITY 
OF THIS FEATURE TO THE DISCUSSION AREA WILL BRING AN INCREASE IN 
WINDS AND SEAS PARTICULARLY N OF 26N W OF 125W. EXPECT W TO NW 
WINDS OF 20 TO LOCALLY 30 KT AND BUILDING SEAS TO 16 TO 17 FT IN 
NW SWELL TONIGHT INTO SUN. THE LOW PRES WILL MOVE NE AND BE 
ABSORBED BY A STRONGER COLD FRONT WHICH IS FORECAST TO REACH THE 
NW PART OF THE DISCUSSION AREA BY TUE. ELSEWHERE...A 1017 MB 
HIGH CENTERED NEAR 25N120W IS EXPECTED TO WEAKEN OVER THE NEXT 
FEW DAYS AS THE AFOREMENTIONED COLD FRONT MOVES EASTWARD AND 
GRADUALLY DISSIPATES.  

FURTHER SOUTH...A 1010 MB LOW PRES IS CENTERED ALONG THE ITCZ 
NEAR 07N100W DRIFTING WESTWARD. THIS SYSTEM IS TRIGGERING 
SPORADIC DEEP CONVECTION AT TIMES WITH A SMALL AREA OF 20 KT 
WINDS WITHIN 60 NM N SEMICIRCLE OF LOW CENTER. A SURFACE TROUGH 
REMAINS EMBEDDED WITHIN THE ITCZ ANALYZED FROM 17N119W TO 
08N122W. GLOBAL MODELS SHOW THIS FEATURE PERSISTING WITHIN THE 
ITCZ THROUGH THE WEEKEND WHILE DRIFTING WESTWARD. WINDS ARE 
FORECAST TO INCREASE TO 20 KT IN THE GRADIENT NW OF THE TROUGH 
AXIS SUN NIGHT AND MON.

GAP WINDS...
CURRENTLY...WINDS ARE BELOW GALE FORCE THROUGH THE GULF OF 
TEHUANTEPEC AREA WITH MINATITLAN MEXICO REPORTING NORTHERLY 
WINDS OF 25 KT WITH GUSTS TO 35 KT. HOWEVER...A HIGH PRESSURE 
RIDGE WILL REMAIN OVER THE SW GULF OF MEXICO AND PORTIONS OF 
INTERIOR SOUTHERN MEXICO THROUGH LATE SUN. SURFACE PRESSURES 
BUILD ON MON IN THE WAKE OF A SURGE OF ARCTIC AIR. THIS WILL 
ALLOW WINDS TO ONCE AGAIN REACH GALE FORCE EARLY MON AND 
CONTINUING INTO TUE OVER THE GULF OF TEHUANTEPEC. A GALE WARNING 
HAS BEEN POSTED IN THE HIGH SEAS FORECAST FOR THE AREA BEGINNING 
1200 UTC MON.  

GAP WINDS FUNNELING THROUGH THE GULF OF PAPAGAYO ARE EXPECTED TO 
CONTINUE OVER THE NEXT 48 HOURS WITH NE WINDS PULSING TO 20 TO 
25 KT AS HIGH PRES BUILDS OVER THE WESTERN CARIBBEAN. WINDS ARE 
NORMALLY GREATEST DURING THE OVERNIGHT AND EARLY MORNING HOURS 
WITH THE ASSISTANCE OF THE NOCTURNAL DRAINAGE FLOW.

$$
COBB