000 AXPZ20 KNHC 200929 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC THU MAY 20 2010 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 0715 UTC. ...TROPICAL WAVES... TROPICAL WAVE ALONG 83W N OF 02N IS MOVING W AT 10 KT. SCATTERED MODERATE TO STRONG CONVECTION CAN BE FOUND N OF 05N WITHIN 210 NM E AND 270 NM W OF WAVE WHICH INCLUDES THE COASTAL AREAS FROM PANAMA THROUGH THE GULF OF FONSECA. THE WAVE LIES ON THE SE SIDE OF AN UPPER ANTICYCLONE. CONDITIONS ALOFT ARE MODERATELY DIFFLUENT AND THEY ARE EXPECTED TO REMAIN SO FOR THE NEXT FEW DAYS. THIS SHOULD ALLOW CONVECTION TO CONTINUE NEAR THIS WAVE. TROPICAL WAVE FROM 12N103W TO 03N104W IS MOVING W AT 15 KT. THIS WAVE IS ASSOCIATED WITH A WELL DEFINED MID LEVEL CIRCULATION. CONVECTION NEAR THE WAVE HAS DECREASED MARKEDLY OVER THE LAST 6 HOURS AS THE WAVE HAS ENCOUNTERED INCREASING EAST-NORTHEASTERLY SHEAR. ...ITCZ... THE INTERTROPICAL CONVERGENCE ZONE AXIS IS ALONG 08N85W TO 08N102W TO 07N115W TO 08N125W TO 05N140W. SCATTERED MODERATE CONVECTION CAN BE FOUND WITHIN 180 NM S OF THE ITCZ AXIS BETWEEN 89W AND 91W AS WELL AS WITHIN 45 NM S OF THE ITCZ AXIS BETWEEN 95W AND 97W. ...DISCUSSION... A WEAKENING COLD FRONT IS GRAZING NW WATERS AND IS USHERING IN HIGH PRES BEHIND IT STEMMING FROM A 1029 MB HIGH NEAR 35N143W. THERE IS A TIGHT PRES GRADIENT IN PLACE BETWEEN THE RIDGING OVER MUCH OF THE FORECAST AREA N OF 20N AND TROUGHING FROM THE SOUTHERN PLAINS THROUGH CENTRAL MEXICO. NW TO N WINDS ALONG THE W COAST OF BAJA CALIFORNIA ARE IN THE 20-25 KT RANGE ACCORDING TO THE 0134 WINDSAT PASS AND SHIP DGSE REPORTED 27 KT NEAR 23N111W AT 0600 UTC. THE STRONG PRES GRADIENT OVER NE WATERS WILL BE MAINTAINED THROUGH THE FORECAST PERIOD AS THE ENERGY ASSOCIATED WITH THE AFOREMENTIONED COLD FRONT MOVES INTO THE SW U.S. AND REINFORCES THE TROUGHING OVER THE CONTINENT WHILE THE SUBTROPICAL HIGH CONTINUES TO BUILD BEHIND THE COLD FRONT. LOOK FOR 20-25 KT WINDS TO EXPAND W TO NEAR 125W OVERNIGHT TONIGHT AND REMAIN IN PLACE THROUGH FRI. ALSO...LOOK FOR NE TRADE WINDS TO EXPAND N OVER THE NEXT FEW DAYS AS A RESULT OF THE INCREASED PRES GRADIENT BETWEEN THE BUILDING SUBTROPICAL HIGH AND THE ITCZ TO THE S. AN UPPER LEVEL ANTICYCLONE IS CENTERED NEAR 14N94W WITH A RIDGE AXIS EXTENDING SE THROUGH SOUTHERN NICARAGUA. THE DIFFLUENT CONDITIONS INDUCED BY THE RIDGE ALOFT IS ENHANCING THE AFOREMENTIONED MODERATE TO STRONG CONVECTION ASSOCIATED WITH A TROPICAL WAVE ALONG 83W. THE RIDGE ALSO EXTENDS SW OF THE ANTICYCLONE CENTER TOWARD 12N120W AND THEN TURNS S TOWARD ANOTHER ANTICYCLONE NEAR 08N126W. MEANWHILE...A 50-70 KT W-SW UPPER JET PARALLELS THE RIDGE AXIS WITH ITS JET CORE APPROXIMATELY 510 NM N OF THIS RIDGE. THE JET IS TRANSPORTING CONVECTIVE DEBRIS FROM THE ITCZ NORTHEASTWARD INTO SOUTHERN MEXICO. A 1009 MB LOW PRES CENTER IS EMBEDDED IN THE ITCZ NEAR 08N125W...UNDER THE WESTERN ANTICYCLONE. DESPITE FAVORABLE CONDITIONS ALOFT AND AVAILABLE LOW LEVEL MOISTURE...THERE IS NO SIGNIFICANT CONVECTION CURRENTLY ASSOCIATED WITH THIS LOW. CROSS-EQUATORIAL LONG PERIOD SW SWELL HAS REACHED MUCH OF THE PACIFIC COASTLINE WITHIN THE FORECAST AREA WITH WAVE HEIGHTS IN THE 4-6 FT RANGE...WITH THE EXCEPTION OF THE W COAST OF BAJA CALIFORNIA WHERE NW WIND WAVES HAVE DRIVEN SEAS UP TO 6-8 FT. THE HIGHEST ENERGY WAVE FIELD...WITH SWELL UP TO 20 SECONDS AND SIGNIFICANT WAVE HEIGHTS TO 11 FT...IS CURRENTLY PROPAGATING THROUGH SW WATERS PRIMARILY SW OF A LINE FROM 00N98W TO 20N130W. THIS WAVE TRAIN IS EXCEPTED TO REACH THE MEXICAN AND CENTRAL AMERICAN COAST BY FRI MORNING AND WILL INCREASE WAVES TO 10 FT IN 20 SECOND SWELL IN THE COASTAL WATERS FRI INTO THE WEEKEND...MAKING FOR DANGEROUS SURF CONDITIONS ESPECIALLY ON SOUTH FACING BEACHES. SEAS ARE EXPECTED TO RISE ABOVE 8 FEET OVER THE ENTIRE FORECAST AREA BY SAT MORNING AS THE SW SWELL SPREADS NORTH THROUGH THE REGION. $$ SCHAUER