000 AXPZ20 KNHC 182222 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC MON DEC 18 2006 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2145 UTC. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 6N77W 6N90W 6N100W 9.5N110W 8N122W 7N130W 6N140W. SCATTERED STRONG WITHIN 60 NM EITHER SIDE OF AXIS BETWEEN 120W-124W. SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 240 NM N OF AXIS BETWEEN 106.5W-109W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 60 NM EITHER SIDE OF THE AXIS BETWEEN 133W-139W. SCATTERED MODERATE CONVECTION IS WITHIN 90 NM EITHER SIDE OF THE AXIS BETWEEN 114W-116W AND ALSO BETWEEN 118W-120W. ...DISCUSSION... THE SUBTROPICS IS DOMINATED BY A RIGOROUS SHORTWAVE TROUGH WITH ITS AXIS EXTENDING FROM 32N117W SOUTHWEST THROUGH 22N124W TO BASE AT 14N134W. DIFFLUENT FLOW PATTERN SOUTHEAST OF THE TROUGH IS RESULTING IN AN AREA OF ENHANCED DEEP THUNDERSTORM ACTIVITY ...MORE THAN TYPICALLY SEEN FOR THIS TIME OF YEAR...NORTH OF THE ITCZ FROM 10.5N-14N BETWEEN 106W-110W. THIS CONVECTION IS ALSO ASSOCIATED WITH A SURFACE TROUGH MOVING WESTWARD ABOUT 15 KT. SOME OF THIS ACTIVITY...ONES WITH THE LOWER CLOUD TOPS...WILL TRANSLATE WESTWARD OVER THE NEXT 3-4 DAYS. UPPER LEVEL DEBRIS MOISTURE FROM THE DEEP TROPICS IS BEING CHANNELED NORTHEASTWARD TOWARDS MEXICO AHEAD OF THE TROUGH. MOST RECENT SATELLITE WATER VAPOR IMAGERY DEPICTS A BAND OF DRY UPPER AIR WITHIN 240 NM EITHER SIDE OF A LINE ROUGHLY EXTENDING FROM 30N120W TO 23N128W 14N138W. WEAK MID/UPPER LEVEL RIDGING JUST W OF THE AREA EXTENDS FROM 23N144W NORTHEASTWARD THROUGH 27N140W TO SHARPENING CREST WELL NORTH OF THE AREA NEAR 34N123W. THIS RIDGE IS FORECAST TO LIKELY SHIFT SOUTHEASTWARD INTO THE WESTERN PORTION OF THE DISCUSSION AREA AS ANOTHER STRONG SHORTWAVE CURRENTLY WEST OF THE AREA EXTENDING FROM ABOUT 32N144W SOUTHWESTWARD TO THE HAWAIIAN MOVES RAPIDLY EASTWARD REACHING CENTRAL AND SOUTHERN CALIFORNIA WED. THE TROPICS CONTINUES TO BE DOMINATED BY MID TO UPPER RIDGING ALONG 5N WEST OF 110W. CONVECTION ALONG THE ITCZ IS ENHANCE UNDER THIS RIDGE MAINLY BETWEEN 118W-125W. TO THE EAST OF THIS RIDGING...A MID/UPPER LEVEL TROUGH DIGS WELL SOUTHWARD INTO THE TROPICS FROM SOUTHEASTERN MEXICO...WHERE IT APPEARS RATHER SUBTLE...SOUTH ALONG 97W TO THE EQUATOR. THE UPPER LEVEL FLOW IS SOUTHWESTERLY EAST OF THE TROUGH...THEN BECOMES ANTICYCLONIC 90W IN RESPONSE TO A MID/UPPER LEVEL ANTICYCLONE NEAR 8N88W. MODERATE TO STRONG SUBSIDENCE AND ASSOCIATED DRY AIR COVERS THE EASTERN PORTION OF THE AREA SOUTH OF 15N EAST OF 102W. ONLY ISOLATED SHOWERS AND THUNDERSTORMS MOVING WESTWARD 10-15 KT ARE NOTED SOUTH OF 8N EAST OF 94W. LOW LEVELS...HIGH PRESSURE OF 1032 MB IS ANALYZED NORTH OF THE AREA NEAR 33.5N132W WITH A RIDGE EXTENDING SOUTHEASTWARD THROUGH 26N122W TO 23N114W. HIGH PRESSURE COVERS THE AREA NORTH OF 15N WEST OF 110W. SURFACE COLD FRONT ASSOCIATED WITH THE NEXT MID/UPPER LEVEL TROUGH AS MENTIONED EARLIER IN DISCUSSION IS NEARING THE DISCUSSION AREA FROM 32N145W TO WELL WEST OF THE AREA NEAR 26N156W. THIS FRONT WILL BEGIN TO MOVE INTO THE NORTHWEST CORNER OF THE REGION BY ABOUT LATE WED INTO THU MORNING...AND WILL LIKELY PRECEDED BY A BAND OF SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS. A 150 NM WIDE BAND...RESIDUAL CLOUDS/SHOWERS FROM AN OLD FRONTAL BOUNDARY EXTENDS FROM 22.5N116W WESTWARD ALONG 20N124.5W 17N135W TO 17N140W. SCATTERED TO BROKEN COLD AIR STRATOCUMULUS CLOUDS WITH POSSIBLE ISOLATED SHOWERS ARE NOTED NORTH OF 20N AND WEST OF 117W. CLOUDS EAST OF 130W ARE MOVING SOUTH-SOUTHWEST AND THOSE WEST OF 130W ARE MOVING GENERALLY WESTWARD EXCEPT NORTHWEST NORTH OF 25N AND WEST OF 135W IN RESPONSE TO SOUTH-EASTERLY FLOW AHEAD OF THE APPROACHING COLD FRONT. GAP WINDS...N-NE WINDS TO 20 KT PRESENTLY IN GULF OF TEHUANTEPEC EXPECTED TO LAST FOR ABOUT 24 HOURS. NE WINDS TO 20 KT SEAS TO 8 FT IN THE GULF OF PAPAGAYO EXPECTED TO CONTINUE FOR 48 HOURS AS JUST ENOUGH OF A TIGHT PRESSURE GRADIENT OVER CENTRAL AMERICA AND THE WESTERN CARIBBEAN HOLDS. $$ AGUIRRE