000
AXPZ20 KNHC 222203
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC TUE DEC 22 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...

ITCZ AXIS IS CENTERED ALONG 7N80W 5N90W 4N103W 5N115W 8N122W 
8N131W 9N140W. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM
S OF THE AXIS E OF 79W.

...DISCUSSION...

LONGWAVE TROUGH W OF THE AREA APPROACHING 144W WILL CONTINUE 
EASTWARD EXPECTED TO MOVE INTO THE WESTERN PORTION OF THE AREA 
WITHIN THE NEXT 24 HRS. A SMALL CYCLONIC CIRCULATION E OF THE 
TROUGH HAS PULLED NNE IS PRESENTLY JUST NW OF THE AREA NEAR 
31N138W. E OF THE AREA OVER THE DISCUSSION AREA...BROAD 
MID/UPPER ANTICYCLONIC
FLOW IS RATHER PRONOUNCED WITH A MEAN RIDGE AXIS EXTENDING FROM
30N128W TO 20N124W TO 15N122W TO NEAR 8N118W. A JET STREAM BRANCH
ENTERS THE AREA AHEAD OF THE TROUGH THROUGH 22N140W...AND EXTENDS
NE  29N131W THEN CONTINUES E TOWARDS CENTRAL BAJA CALIFORNIA. 
STRONG SW TO W WINDS WITH SPEEDS OF 60-90 KT ARE WITHIN THE JET
CORE FROM 23N TO 27N BETWEEN 120W AND 131W. OVER THE FAR NE 
PORTION...A STRONG SHORTWAVE TROUGH HAS JUST ABOUT MOVED INLAND
SOUTHERN CALIFORNIA WITH FAST WLY FLOW FOLLOWING BEHIND IT. THE
ASSOCIATED SURFACE COLD FRONT EXTENDS FROM FAR NW MEXICO SW TO
CENTRAL BAJA CALIFORNIA NEAR 28N114W AND TO NEAR 26N117W WHERE
IT BECOMES RATHER DIFFUSE. A PLUME OF UPPER LEVEL MOISTURE 
CONSISTING OF BROKEN TO OVERCAST MID AND HIGH CLOUDS DUE TO THE 
TROUGH COVERS THE EASTERN SECTION OF THE AREA WITHIN 150 NM 
EITHER SIDE OF A LINE FROM 24N123W TO 25N117W TO ACROSS CENTRAL 
BAJA AND TO ACROSS NORTHERN MEXICO. THE MOISTURE EMANATES FROM 
ITCZ CONVECTION WEST OF 130W AND ALSO DUE TO THE GENERAL RISING 
MOTION ON THE EAST FLANK OF THE TROUGH. MOISTURE AND MULTIPLE 
LEVEL BROKEN TO OVERCAST CLOUDS ARE OVER MEXICO NORTH OF 24N AND 
ARE ASSOCIATED WITH THE SHORTWAVE APPROACHING FROM THE WEST. 

ANOTHER TROUGH IS OVER EASTERN MEXICO WITH A NEGATIVELY TILTED 
TROUGH AXIS FROM THE YUCATAN PENINSULA NEAR 21N88W TO 
SOUTHWESTERN COLOMBIA. SOUTHERLY FLOW EAST OF THE TROUGH AXIS IS 
BRINGING MOISTURE FROM ITCZ CONVECTION NORTH OVER CENTRAL 
AMERICA EAST OF COSTA RICA. DRYING IS NOTED OVER COSTA RICA 
WESTWARD AS THE TROUGH SWINGS EAST. IN THIS MOIST REGION 
MULTIPLE LEVEL OVERCAST TO BROKEN CLOUDS ARE NORTH OF THE ITCZ 
WITH SOME EMBEDDED CONVECTION.  

WEST OF THE TROUGH AXIS AND EAST OF THE MOISTURE MENTIONED IN 
THE FIRST PARAGRAPH...THAT IS THE AREA BETWEEN THE TWO TROUGHS 
...IS A LARGE SCALE DEEP LAYER WEAKENING RIDGE WITH MOSTLY DRY 
AND CLOUD FREE MIDDLE AND UPPER LEVELS. 

OTHER THAN THE COLD FRONT MENTIONED ABOVE A WEAK RIDGE IS NORTH 
OF 15N. WEAK LOW PRESSURE 1011 MB IS CENTERED NEAR 14N124W WITH 
A BROAD TROUGH SOUTH TO THE ITCZ. OTHERWISE A BROAD TROUGH 
CENTERED ON THE ITCZ IS ANALYZED AT THE SURFACE.

GAP N WINDS OF 20 KT ARE OCCURRING THROUGH THE GULF OF 
TEHUANTEPEC AND ARE EXPECTED TO DIMINISH WITHIN ABOUT 6 HRS.

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