000
AXPZ20 KNHC 250341
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC FRI DEC 25 2009

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

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0315 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 8N79W 5N95W 8N111W 8N120W 8N140W. 
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 180 NM 
N OF THE AXIS BETWEEN 123W-127W. SCATTERED MODERATE CONVECTION 
IS S OF THE ITCZ WITHIN 30 NM OF 5N119W.

...DISCUSSION...

A LARGE UPPER LEVEL TROUGH HAS CROSSED IN THE FAR WESTERN 
PORTION OF THE AREA...AND EXTENDS FROM 30N126W TO 18N128W TO 
12N132W TO 9N134W TO W OF THE AREA AT 4N140W. AT THE SURFACE
...A COLD FRONT IS ABOUT 210 NM NW OF THE AREA. WIDELY SCATTERED 
SHOWERS AND ISOLATED WEAK TSTMS ARE JUST NW OF THE AREA AHEAD OF 
THE FRONT. SURFACE WINDS OVER THE NW PORTION OF THE AREA HAVE 
RESPONDED TO THE FRONT...AND ARE SE TO S 20 TO 25 KT N OF 25N W 
OF 135W WITH SEAS 10 TO 15 FT IN A NW SWELL. THE FRONT IS 
FORECAST TO REACH FROM NEAR 31N135W TO 25N140W IN 24 HRS...AND 
FROM 30N125W TO 25N132W DISSIPATING TO 20N140W IN 48 HRS WITH NW 
SWELLS BUILDING UP TO 19 FT BEHIND IT IN 24 HRS...SUBSIDING
SLIGHTLY IN ABOUT 48 HRS.

THE REMAINDER OF THE DISCUSSION AREA E OF THE TROUGH IS UNDER 
THE DOMINANCE OF RATHER BROAD MID/UPPER LEVEL RIDGING WITH A 
FAINT RIDGE AXIS EXTENDING FROM 30N118W TO 18N110W TO A 
MID/UPPER LEVEL ANTICYLONE MOVING ENE NEAR 10N98W. A 1021 MB 
HIGH CENTER IS N OF THE AREA NEAR 37N127W WITH A RIDGE SW TO 
30N131W TO 24N136W. A JET STREAM BRANCH EXTENDS NE FROM 18N132W 
TO 23N123W WHERE IT MERGES WITH ANOTHER JET BRANCH FROM THE NW. 
THE MERGED BRANCH THAN MAKES AN EASTWARD TRAJECTORY TOWARDS 
CENTRAL BAJA CALIFORNIA AND ACROSS NORTHERN MEXICO TO INTO THE 
WESTERN GULF OF MEXICO. MAXIMUM JET CORE WIND SPEEDS AS NOTED BY 
SATELLITE DERIVED WIND DATA ARE IN THE RANGE OF 60-100 KT. OVER 
THE FAR NE PORTION CONFLUENT FLOW PATTERN IS NOTED TO THE NE OF 
THE MID/UPPER LEVEL RIDGE. A SMALL POCKET OF DRY AIR HAS PUSHED 
EASTWARD TO OVER FAR NORTHERN BAJA CALIFORNIA AND NORTHERN 
MEXICO.

THE UPPER FLOW AHEAD OF THE TROUGH CONTINUES TO PULL A PLUME OF 
MOSTLY MID AND UPPER LEVEL MOISTURE DERIVED FROM THE ITCZ 
CONSISTING OF MOSTLY BROKEN HIGH CLOUDS NE AND E OVER THE AREA 
FROM 9N TO 19N W OF 120W...AND N OF 12N E OF 120W TO ACROSS
BAJA CALIFORNIA AND OVER NORTHERN AND CENTRAL MEXICO...AND
AS FAR E AS THE GULF OF MEXICO. SCATTERED TO BROKEN PATCHES OF 
LOW CLOUDS WITH ISOLATED SHOWERS ARE N OF 19N W OF 125W.

ELSEWHERE AT THE SURFACE...A WEAK AND PERSISTENT WEAK 1011 MB 
LOW MOVING W ABOUT 7 KT IS NEAR 8N126W WITH A TROUGH N TO 11N.  
AN AREA OF NE TO E 20 KT TRADE WINDS INDUCED BY A TIGHTENING OF 
THE PRES GRADIENT BETWEEN SURFACE HIGH PRES TO THE N AND NW OF 
THE LOW IS LOCATED FROM 15N TO 22N BETWEEN 120W AND 132W. WITH 
THE LOW WEAKENING FURTHER AND HIGH PRES TO THE N ALSO WEAKENING 
IN ADVANCE OF A STRONGER COLD FRONT APPROACHING THE FAR NW 
PORTION OF THE AREA...THESE WINDS WILL DIMINISH THROUGH THE  
NEXT 24 HRS...BUT SEAS UP TO 12 FT IN LARGE NW SWELLS WILL BE 
POSSIBLE OVER THE FAR W AND NW SECTIONS THROUGH FRI. TRADES
MAY INCREASE OVER THE FAR WESTERN PORTION OF THE AREA LATE
SAT INTO SUN AS STRONGER HIGH PRES BUILDS EASTWARD INTO THE NW
PORTION OF THE AREA.

THE SOUTHERN PORTION OF A RATHER SHARP MID/UPPER LEVEL TROUGH 
EXTENDS FROM THE FAR WESTERN CARIBBEAN SEA SSW TO ACROSS CENTRAL 
AMERICA...AND REACHES TO NEAR 4N87W. EARLIER SHOWER ACTIVITY NEAR
THE TAIL END OF TROUGH HAVE SINCE DISSIPATED. THE UPPER FLOW 
PATTERN BETWEEN THE TROUGH AND THE WESTERN EXTENSION OF 
MID/UPPER LEVEL RIDGING THAT EXTENDS OVER S AMERICA ALONG 8N IS 
ADVECTING UPPER LEVEL ITCZ MOISTURE NORTHWARD ACROSS PANAMA FROM 
N OF 5N. SATELLITE WATER VAPOR IMAGERY SHOWED ABUNDANT MODERATE 
SUBSIDENCE INDICATIVE OF DRY SINKING AIR AND VERY STABLE 
CONDITIONS COVERING JUST ABOUT THE ENTIRE AREA S AND SE OF THE 
ABOVE MENTIONED PLUME OF CLOUDS.

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