000
AXPZ20 KNHC 241558
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU DEC 24 2009

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 
1545 UTC.

...ITCZ...
ITCZ AXIS IS ALONG 07N78W TO 09N85W TO 05N100W TO 08N112W TO 
08N140W. SCATTERED MODERATE TO STRONG CONVECTION IS NOTED FROM 
06N TO 13N BETWEEN 118W AND 125W. ISOLATED MODERATE ALONG 06N 
BETWEEN 85W AND 91W AND NEAR 07N135W.  

...DISCUSSION...
A SERIES OF UPPER LEVEL TROUGHS DOMINATE THE WESTERN PORTION OF 
THE DISCUSSION AREA. THE FIRST TROUGH AXIS IS NOTED ALONG 
32N128W TO 17N132W. THE SECOND TROUGH IS ALONG 32N138W TO 
18N138W. DRY UPPER AIR IS NOTED W OF THE SECOND TROUGH WHILE 
UPPER MOISTURE IS INDICATED BETWEEN BOTH TROUGHS. FURTHER E AN 
UPPER TROUGH THAT LIES ACROSS CENTRAL N AMERICA ALONG 104W 
CONTINUES S INTO AN UPPER CYCLONE AT 31N191W AND CONTINUES S 
ACROSS OLD MEXICO TO A BASE AT 21N100W. DRY UPPER AIR IS 
SWINGING E THROUGH THE THIS TROUGH OVER THE AREA N OF POINTS 
31N116W TO 23N104W TO 31N94W. 

AN UPPER ANTICYCLONE IS CENTERED OVER THE EQUATOR AT 130W WITH A 
RIDGE EXTENDING N TO A CREST AT 32N122W. A SECOND UPPER 
ANTICYCLONE IS NOTED NEAR 08N114W. AS PREVIOUSLY MENTIONED... 
ITCZ CONVECTION IS ENHANCED UNDER THE RIDGE...FROM 06N TO 13N 
BETWEEN 118W AND 125W...WITH AN INTERMITTENT SURFACE CYCLONE OF 
1010 MB AT 08N125W. ASSOCIATED DEBRIS MOISTURE IS ADVECTED N 
MERGING WITH A PERSISTENT MOISTURE PLUME ALSO TRAPPED UNDER THE 
UPPER RIDGE. SOME OF THE MOISTURE CONTINUES E OF THE RIDGE IN 
UPPER WESTERLIES THROUGH THE DOWNSTREAM UPPER TROUGH...ACROSS 
OLD MEXICO AND THE GULF OF MEXICO...ROUGHLY FROM 18N TO 25N 
BETWEEN 115W AND 85W. THE MOISTURE APPEARS TO BE EVAPORATING 
BETWEEN 110W AND 98W AT THE MOMENT.  

AN UPPER TROUGH EXTENDING S ALONG THE E COAST OF CONUS CONTINUES 
SSW ACROSS THE WESTERN CARIBBEAN AND OVER THE TROPICAL PACIFIC 
ALONG 09N82W TO 05N91W WITH ISOLATED CONVECTION ENHANCED OVER 
THE PACIFIC WATERS. AN UPPER CYCLONE IS NOTED NEAR 06N79W WITH A 
ISOLATED CONVECTION BEGINNING TO FLARE ALONG THE COAST OF 
COLOMBIA AT 07N. DRY UPPER AIR IS INDICATED OVER THE DISCUSSION 
AREA S OF 20N E OF 110W...AND IMMEDIATELY EVAPORATES ANY DEBRIS 
MOISTURE FROM THESE CONVECTIVE BURSTS.
 
AT THE SURFACE...HIGH PRES COVERS THE AREA N OF 17N W OF 115W. 
EASTERLY TRADES OF 20 KT CONTINUE ALONG THE SOUTHERN PERIPHERY 
OF THE RIDGE WITH SOUTHERLY WINDS AT 20 TO 25 KT OVER THE NW 
WATERS IN ADVANCE OF AN APPROACHING COLD FRONT EXPECTED TO ENTER 
THE EXTREME NW PORTION FRI.

GULF OF CALIFORNIA...NORTHERLY FLOW AT 15 TO 20 KT IS EXPECTED 
TO CONTINUE THROUGH FRI NIGHT DIMINISHING BELOW 20 KT EARLY SAT.

GULF OF TEHUANTEPEC...SOUTHERLY WINDS AT 15 TO 20 KT EXPECTED 
TODAY BECOMING N LATE TONIGHT AND INCREASING TO 20 TO 30 KT BY 
LATE FRI THEN DIMINISHING TO 15 TO 20 KT EARLY SAT.

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