000
AXPZ20 KNHC 292205
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC TUE DEC 29 2009

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

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2130 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS CENTERED ALONG 5N77W 
5N90W 5N104W 6N112W 7N124W 6N140W. SCATTERED MODERATE CONVECTION
IS WITHIN 120 NM S OF THE AXIS BETWEEN 116W-122W.
 
...DISCUSSION...

A MID/UPPER LEVEL TROUGH EXTENDS FROM THE WESTERN U.S. SW TO 
27N120W TO 24N128W TO 22N140W. TO ITS SW VERY BROAD UPPER RIDGING
COVERS THE AREA S OF 18N AND W OF 110W. A RATHER SUBTLE SHORTWAVE
TROUGH IS OVER THE FAR EASTERN PORTION OF THE AREA FROM 20N109.5W
TO 15N103W THEN S TO 8N102W AND SW TO 00N105W. JUST ABOUT THE
ENTIRE AREA BETWEEN THE MID/UPPER LEVEL AND RIDGE IS UNDER 
PRETTY FAST ZONAL FLOW WITH SATELLITE WATER VAPOR INDICATING
MODERATE SUBSIDENCE AND ASSOCIATED STABLE ATMOSPHERIC CONDITIONS
NOTED AS PATCHES OF BROKEN STRATOCUMULUS CLOUDS MOVING SSW TO
N OF 13N. UPPER LEVEL MOISTURE IS SPILLING UP AND AROUND A 
LARGE MID/UPPER LEVEL RIDGE W OF THE AREA SOUTHEASTWARD INTO THE 
FAR NORTHERN BOUNDARY OF THE AREA BEHIND THE MID/UPPER LEVEL 
TROUGH. STRONG JEST STREAM BRANCH JUST N OF THE ITCZ IS 
ADVECTING UPPER LEVEL ITCZ MOISTURE NE ACROSS SOUTHERN MEXICO 
AND INTO TEXAS. AN UPPER ANTICYCLONE CENTERED OVER THE CENTRAL 
CARIBBEAN SEA EXTENDS A RIDGE ACROSS CENTRAL AMERICA INTO THE 
EPAC MAINLY E OF 87W. 

AT THE SURFACE...HIGH PRESSURE OF 1026 MB IS CENTERED NEAR 
29N130W WITH A RIDGE TO NEAR 21N112W. RELATIVELY LOWER PRES TO 
THE S IN COMBINATION WITH THE HIGH TO THE N CONTINUES TO RESULT
IN A LARGE SWATH OF FRESH TO STRONG TRADE WINDS OVER AN AREA
S OF 18N W OF 130W AND FROM 7N TO 18N BETWEEN 116W AND 130W.
THE HIGH CENTER IS FORECAST TO MIGRATE E TO NEAR 29N123W IN 24 
HRS AS A COLD FRONT MAKES HEADWAY TOWARDS THE FAR NW CORNER OF 
THE AREA. EXPECT AREA OF TRADES TO INCREASE EASTWARD THROUGH THE 
NEXT 48 HRS AS THE HIGH SHIFTS E. IN ADDITIONS NW WINDS OF 20 TO 
25 KT ARE EXPECTED TO INCREASE THROUGH MUCH OF THE GULF OF 
CALIFORNIA AS WELL DUE TO AN INCREASING PRES GRADIENT BETWEEN 
THE HIGH AND LOWER PRES THROUGH THE GULF OF CALIFORNIA AND FAR 
OVER NW MEXICO.

WITH RESPECT TO ABOVE MENTIONED COLD FRONT...SW WINDS ARE 
FORECAST TO INCREASE OVER THE NW PORTION OF THE AREA BEGINNING 
WED MORNING WITH A NW SWELL TRAIN PRODUCING SEAS OF UP 12 FT 
ACROSS THAT AREA.

GAP WINDS...
GULF OF TEHUANTEPEC...GALE FORCE WINDS HAVE RECENTLY DIMINISHED
TO 30 KT THIS AFTERNOON...AND ARE FORECAST TO FURTHER DIMINISH
TO 20 KT WED AND TO LESS THAN 20 KT BY THU AFTERNOON WITH SEAS
SUBSIDING TO LESS THAN 8 FT ALSO BY THU AFTERNOON.

GULF OF PAPAGAYO...NE TO WINDS OF 20 TO 25 KT ARE EXPECTED TO
LAST THROUGH THU EVENING...AND POSSIBLY LONGER.

SEA CONDITIONS ARE DOMINATED BY LONG PERIOD NW SWELL (WAVE 
PERIODS OF UP TO 17 SECONDS) WITH SIGNIFICANT WAVE HEIGHTS AS 
HIGH AS 13 FT. THIS SWELL EVENT WILL CONTINUE TO SPREAD SE 
REACHING NEAR 90W IN ABOUT 48 HOURS.

FOR ADDITIONAL INFORMATION PLEASE VISIT 
HTTP://WWW.HURRICANES.GOV/MARINE
  
$$
AGUIRRE