000 AXPZ20 KNHC 091553 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC WED DEC 09 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 1500 UTC. ...ITCZ... AXIS ANALYZED ALONG 06N78W TO 08N105W TO 08N117W TO 10N124W TO 07N140W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS WITHIN 180 NM N OF THE AXIS BETWEEN 125W AND 130W...AND IS ALSO WITHIN 90 NM N OF THE AXIS W OF 132W. ...DISCUSSION... LONG PERIOD NW SWELL (WAVE PERIODS BETWEEN 19 TO 20 SECONDS) WITH SIGNIFICANT WAVE HEIGHTS AS HIGH AS 20 FEET HAVE MOVED INTO THE NW WATERS. THIS SWELL IS MOVING OUT AHEAD OF A COLD FRONT POSITIONED FROM 30N134W TO 24N139W. THIS FRONT IS ASSOCIATED WITH AN UPPER LEVEL TROUGH EXTENDING FROM 40N135W TO 33N132W TO 23N139W AS INDICATED BY WATER VAPOR SATELLITE IMAGERY. 20 TO 25 KT SW WINDS CAN CURRENTLY BE FOUND WITHIN 150 NM AHEAD OF THE FRONT. SHIP ZCDA9 HAS BEEN TRAVERSING FROM THE NE TO THE SW OVER THE PAST SEVERAL HOURS AHEAD OF THE FRONT...AND WAS REPORTING SW WINDS OF UP TO 33 KT... HOWEVER QUALITY CONTROL INDICATED THAT THE SHIP HAS A HISTORY OF A HIGH BIAS OF AROUND 8 KT. ADDITIONAL NW SWELL IS ALSO ALREADY IN PLACE E OF THE NEW SET OF NW SWELL...TO ALONG THE COAST OF THE BAJA PENINSULA DUE TO A SYSTEM THAT MOVED INTO THE SW U.S. AND NW MEXICO YESTERDAY. THE NEW BATCH OF HIGHER SWELL WILL CONTINUE TO PROPAGATE TO THE SE ACROSS THE DISCUSSION AREA REACHING TO THE EQUATOR AND BEYOND WITHIN THE NEXT 48 HOURS. ANOTHER UPPER TROUGH IS LOCATED TO THE SE...EXTENDING FROM NEAR THE N/S BAJA PENINSULA BORDER TO 28N128W TO 09N141W. VERY DRY AIR AND STRONG WESTERLY WINDS ALOFT ARE LOCATED W OF THIS TROUGH...WITH THIS AREA VOID OF ANY CONVECTION AT THE SURFACE. HOWEVER...CONVERGENCE BETWEEN THIS TROUGH AND THE ITCZ TO THE S IS ENHANCING CONVECTION ALONG THE ITCZ W OF 125W. TO THE E...A LARGE UPPER ANTICYCLONE IS CENTERED NEAR 16N94W WITH AN UPPER RIDGE AXIS EXTENDING FROM THE NW CARIBBEAN SEA ALL THE WAY TO 11N117W. W OF THE ANTICYCLONE CENTER... MIDDLE TO UPPER LEVEL MOISTURE IS ADVECTING FROM THE ITCZ TO THE N AND NE AROUND THE NW PORTION OF THE ANTICYCLONE...WITH A BROAD AREA OF MID AND HIGH LAYERED CLOUDS IN PLACE. E OF 115W UNDER THE UPPER RIDGE...DRY AND STABLE AIR EXISTS S OF 20N E OF 114W WITH STRONG SUBSIDENCE/SINKING AIR IN PLACE AS INDICATED ON WATER VAPOR SATELLITE IMAGERY. ELSEWHERE...A 1011 MB LOW PRESSURE SYSTEM IS EMBEDDED WITHIN THE ITCZ...POSITIONED NEAR 09N120W...ALONG A SURFACE TROUGH EXTENDING FROM 06N120W TO 17N118W. AN EARLIER 0544 UTC ASCAT PASS SHOWED NE WINDS OF 20 KT JUST W OF THE TROUGH AXIS AND N OF THE LOW CENTER. INFRARED SATELLITE IMAGERY INDICATED SCATTERED MODERATE AND ISOLATED STRONG CONVECTION WITHIN 180 NM IN ALL QUADRANTS OF THE LOW...AND WITHIN 90 NM W OF THE TROUGH AXIS FROM 11N TO 17N. THIS CONVECTION IS BEING ENHANCED BY UPPER LEVEL DIFFLUENCE COUPLED WITH PLENTIFUL LOW LEVEL MOISTURE AS INDICATED BY TOTAL PRECIPITABLE WATER SATELLITE IMAGERY...ALONG WITH INCREASED VERTICAL MOTION IN THE VICINITY OF THE TROUGH AXIS. THE LOW AND TROUGH WILL CONTINUE TO MOVE TO THE W AROUND 10 KT TODAY...BUT WILL DISSIPATE WITHIN THE NEXT 48 HOURS AS THESE FEATURES ENCOUNTER INCREASING SW SHEAR ALOFT. TO THE E...A 1009 MB AREA OF LOW PRES HAS FORMED NEAR 06N80W...OR ABOUT 90 NM S OF THE COAST OF PANAMA. CONVECTION ASSOCIATED WITH THIS LOW REMAINS MINIMAL AND IS DISPLACED TO THE N OF THE LOW DUE TO STRONG SOUTHERLY WINDS ALOFT. GAP WINDS... GULF OF PAPAGAYO...SHIP A8IZ2 NEAR 10N89W AT 0600 UTC CONFIRMED THAT NE WINDS DOWNWIND OF THE GULF OF PAPAGAYO WERE ABOVE 20 KT EARLIER THIS MORNING AS THE EASTERLY TRADES IN THE W CARIBBEAN CONTINUE TO MOVE ACROSS NICARAGUA AND COSTA RICA INTO THE E PACIFIC. HOWEVER... THE TRADE WINDS IN THE FAR SW CARIBBEAN HAVE BEGUN TO DIMINISH...AND SITE MNRS (RIVAS, NICARAGUA) RIGHT ON THE COAST REPORTED NE WINDS AT 6 KT AT 1400 UTC...THUS WINDS OVER THE ADJACENT WATERS ARE LIKELY IN THE PROCESS OF DIMINISHING TO LESS THAN 20 KT. NE FLOW WILL EVENTUALLY INCREASE BACK TO 20 KT OR GREATER ONCE AGAIN BY LATE THU NIGHT AS THE PRES GRADIENT BUILDS IN ACROSS THE WESTERN CARIBBEAN AND AS THE DRAINAGE FLOW OFF THE CENTRAL AMERICA LANDMASS ALSO INCREASES. $$ LEWITSKY