000 AXPZ20 KNHC 090940 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC WED DEC 09 2009 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0830 UTC. ...ITCZ... THE ITCZ AXIS IS ALONG 05N77W TO 07N95W TO 08N110W TO 12N118W TO 07N140W. SCATTERED MODERATE CONVECTION CAN BE FOUND WITHIN 120 NM S OF THE ITCZ AXIS FROM 124W TO 134W AND WITHIN 90 NM N OF THE ITCZ AXIS BETWEEN 125W AND 130W. ...DISCUSSION... LONG PERIOD NW SWELL WITH SIGNIFICANT WAVE HEIGHTS AS HIGH AS 20 FEET HAVE MOVED INTO NW WATERS. THIS SWELL IS MOVING AHEAD OF THE ASSOCIATED COLD FRONT FROM 30N135W TO 24N140W. 20 TO 25 KT SW WINDS CAN CURRENTLY BE FOUND WITHIN 180 NM AHEAD OF THE FRONT AND ISOLATED SHOWERS LIE AHEAD OF THIS FRONT PRIMARILY N OF 26N...WITH THESE SHOWERS BECOMING MORE ORGANIZED NEAR THE FRONTAL BOUNDARY. NW SWELL WAS ALREADY IN PLACE OVER THE WESTERN HALF OF THE FORECAST AREA AS WELL AS ALONG THE COAST OF THE BAJA PENINSULA DUE TO THE SYSTEM THAT MOVED INTO THE SW U.S. AND NW MEXICO YESTERDAY. THE NEW BATCH OF SWELL...IN THE 18 TO 20 SECOND RANGE...WILL PROPAGATE SOUTH ALONG THE BAJA PENINSULA AND REACH THE EQUATOR OVER W WATERS TODAY. MEANWHILE...THE ASSOCIATED COLD FRONT WILL BEGIN TO WEAKEN OVER N CENTRAL WATERS. SEAS WILL SUBSIDE TO THE 8 TO 14 FT RANGE BY THIS TIME FRI MORNING...BUT WILL ENCOMPASS MUCH OF THE FORECAST AREA W OF 110W. A 1011 MB LOW PRES SYSTEM EMBEDDED IN THE ITCZ NEAR 12N118W LIES NEAR THE REAR RIGHT QUADRANT OF A SOUTHWESTERLY UPPER JET AND UNDER AN UPPER RIDGE AXIS STEMMING FROM AN ANTICYCLONE NEAR 16N97W AND EXTENDING WESTWARD TO 11N127W. TOTAL PRECIPITABLE WATER SATELLITE IMAGERY SHOWS MOISTURE IS POOLED NEAR THE LOW AND ITS TROUGH WHICH EXTENDS THROUGH THE LOW FROM 08N119W TO 18N117W. THE UPPER LEVEL DIFFLUENCE COUPLED WITH THE PLENTIFUL LOW LEVEL MOISTURE NEAR THE LOW HAVE ALLOWED FOR SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION TO DEVELOP WITHIN 390 NM S QUADRANT OF THE LOW. SCATTERED MODERATE CONVECTION CAN ALSO BE FOUND NEAR THE ITCZ BETWEEN THIS LOW AND A SURFACE TROUGH EMBEDDED IN THE ITCZ FROM 12N128W TO 07N133W IN THIS REGION INCREASED VERTICAL MOTION. A BAND OF CIRRUS ASSOCIATED WITH THE UPPER MOISTURE TRANSPORT OF THE JET LIES FROM THIS AREA OF CONVECTION TO 20N AND THEN NORTHEASTWARD INTO BAJA CALIFORNIA. THE ANTICYCLONE AND ITS RIDGE ARE EXPECTED TO RETREAT EASTWARD OVER THE NEXT TWO DAYS AS THE UPPER TROUGH ASSOCIATED WITH THE COLD FRONT OVER NW WATERS PUSHES EASTWARD. THE UPPER JET LIES ON THE LEADING EDGE OF THIS POSITIVELY TILTED TROUGH AND THE REAR RIGHT QUADRANT OF THIS WEAKENING UPPER JET WILL REMAIN RELATIVELY STATIONARY...ALLOWING THE BEST CHANCE OF CONVECTION TO STAY IN THE SAME REGION ALONG THE ITCZ OVER THE NEXT DAY OR SO. ELSEWHERE...SATELLITE WATER VAPOR IMAGERY SHOWS MODERATE SUBSIDENCE OVER THE AREA S OF 15N E OF 115W. THERE IS NO NOTABLE DEEP CONVECTION IN THIS REGION...WITH ONLY SCATTERED SHOWERS FOCUSED NEAR TWO WEAK TROUGHS EMBEDDED IN THE ITCZ FROM 12N108W TO 06N116W AND FROM 09N96W TO 03N97W...RESPECTIVELY. CLOSER TO SHORE...SHIPS LAOX5 AND 9HJB9 HAVE CONFIRMED WINDS TO 20 KT E OF 108N TO THE MEXICAN COAST BETWEEN 18N AND 21N. THE NW TO N WINDS HERE ARE DUE TO THE STRONG PRES GRADIENT BETWEEN THE HIGH PRES RIDGE EXTENDING FROM A 1022 MB SURFACE HIGH NEAR 29N122W TO 21N107W AND LOWER PRES ANALYZED OVER THE WESTERN GULF OF MEXICO AND OVER CENTRAL MEXICO SOUTH OF THE SIERRA MADRE OCCIDENTAL. THIS PRES GRADIENT IS EXPECTED TO SLACKEN THU AS THE COLD FRONT PUSHES THROUGH N WATERS WEAKENING THE RIDGE AND PRESSURES RISE OVER THE WESTERN GULF BEHIND A NEW COLD FRONT. GAP WINDS... GULF OF PAPAGAYO...SHIP A8IZ2 NEAR 10N89W AT 0600 UTC CONFIRMS THAT NE WINDS DOWNWIND OF THE GULF OF PAPAGAYO CONTINUE TO BE ABOVE 20 KT THIS MORNING AS THE EASTERLY TRADES IN THE W CARIBBEAN CONTINUE BLEED THROUGH NICARAGUA AND COSTA RICA INTO THE PACIFIC. HOWEVER...THE TRADE WINDS IN THE FAR SW CARIBBEAN HAVE BEGUN TO DIMINISH. LOOK FOR WINDS TO DROP BELOW 20 KT DOWNWIND OF PAPAGAYO BY AFTERNOON AS A RESULT...BUT NE FLOW SHOULD AGAIN INCREASE TO 20 KT EARLY FRI MORNING AS THE PRES GRADIENT BUILDS IN THE WESTERN CARIBBEAN AND THE DRAINAGE FLOW OFF THE LANDMASS INCREASES MAXIMUM. $$ SCHAUER