000 AXPZ20 KNHC 160322 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC THU APR 16 2009 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0300 UTC. ...ITCZ... THE INTERTROPICAL CONVERGENCE ZONE IS ALONG A LINE FROM 06N77W TO 04N84W TO 05N104W TO 08N120W TO 06N140W. SCATTERED MODERATE CONVECTION CAN BE FOUND WITHIN 120 NM S OF THE ITCZ AXIS FROM 86W TO 91W AND WITHIN 45 NM N AND 120 NM S OF THE ITCZ AXIS FROM 127W TO 135W. ...DISCUSSION... N OF 20N... A DEEP LAYERED LOW PRES SYSTEM CURRENTLY OVER THE GREAT BASIN WILL SLOWLY MOVE EASTWARD THROUGH THE ROCKY MOUNTAINS OVER THE NEXT TWO DAYS. AT THE SURFACE...THE PRES GRADIENT BETWEEN LOW PRES OVER THE GREAT BASIN AND THE HIGH PRES CENTER NEAR 33N132W HAS BROUGHT WINDY CONDITIONS TO NE WATERS. THE ASCAT PASSES FROM 1838 AND 1658 UTC SHOW A REGION W OF NORTHERN BAJA CALIFORNIA TO APPROXIMATELY 122W WHERE WINDS ARE TO 20 KT. CONSIDERING THE GAP IN ASCAT COVERAGE OVER THE REGION OF PEAK WINDS NEAR 30N AND AN EARLIER SHIP OBSERVATION...PHFV...REPORTING WINDS TO 24 KT NEAR 28N115W AT 1700 UTC...BELIEVE WINDS IN THE REGION REMAIN IN THE 20 TO 25 KT RANGE FOR NOW. EXPECT THE AREA OF STRONG WINDS TO DIMINISH OVER THE NEXT TWO DAYS AS THE LOW PRESSURE SYSTEM SLOWLY MOVES E INTO THE PLAINS. N TO NW SWELL HAS GENERATED SEAS IN THE 12 TO 15 FT RANGE OFF THE NORTHERN BAJA CALIFORNIA COAST AS FAR W AS 125W. AS THE WINDS DIMINISH ALONG THE WEST COAST OF THE U.S. AND NW MEXICO...THE SEAS WILL ALSO COME DOWN TO APPROXIMATELY 10 FT OFF BAJA CALIFORNIA OVER THE NEXT 36 HOURS AS THIS SWELL REACHES THE SOUTHERN HALF OF THE PENINSULA. THE STRONG PRESSURE GRADIENT OVER WESTERN NORTH AMERICA HAS ALSO INCREASED WINDS IN THE NORTHERN GULF OF CALIFORNIA. THE QUIKSCAT PASS FROM 1308 UTC SHOWED SW WINDS AHEAD OF THE COLD FRONT ASSOCIATED WITH THE DEEP LAYERED LOW PRESSURE SYSTEM OVER THE WESTERN UNITED STATES INCREASING TO THE 20 TO 30 KT RANGE. THE MORE RECENT ASCAT PASS FROM 1658 UTC HAD PATCHY COVERAGE OVER THE AREA BUT STILL SHOWED WINDS TO 20 KT AND SHIFTING NORTHERLY. ACCORDING TO THE 0000 UTC SURFACE ANALYSIS...THE COLD FRONT HAS DISSIPATED OVER THE GULF OF CALIFORNIA...LIFTING NORTHWARD AS IT TREKS E THROUGH THE HIGH TERRAIN...MAKING WAY FOR NORTHERLY LOW LEVEL FLOW TO SURGE SOUTHWARD THROUGH THE GULF OF CALIFORNIA THU. S OF 20N... AN ASHFALL ADVISORY IS IN EFFECT FROM THE ONGOING ERUPTION OF LA CUMBRE VOLCANO ON ISLA FERNANDINA IN THE GALAPAGOS ISLANDS LOCATED AT 00.4S91.5W. ON THE RECOMMENDATION OF THE NESDIS SATELLITE ANALYSIS BRANCH...THE ASHFALL ADVISORY WILL REMAIN IN EFFECT FOR AT LEAST THE NEXT FEW DAYS DUE TO THE UNCERTAINTY IN THE TIMING OF THE END OF THE VOLCANIC ACTIVITY. AT LEAST THE LAST TWO RUNS OF THE GFS HAVE TURNED THE WINDS OVER THE REGION MORE SOUTHERLY INITIALLY AND INTO THE FORECAST PERIOD. THE WINDS HAVE DOMINANTLY BEEN FROM THE EAST THIS AFTERNOON/EVENING. THE REMAINING MODEL GUIDANCE IS VERIFYING BETTER BY KEEPING THE WIND DIRECTION EAST-SOUTHEASTERLY. THEREFORE...WINDS ARE FORECAST TO REMAIN E-SE NEAR 10 KT IN THIS AREA FOR THE NEXT FEW DAYS. MARINERS SHOULD EXERCISE CAUTION DUE TO REDUCED VISIBILITIES CAUSED BY VOLCANIC ASH DOWNWIND OF THE VOLCANO FROM 02S TO 01N BETWEEN 91W AND 97W FOR AT LEAST THE NEXT FEW DAYS. IN ADDITION...NASA OMI IMAGERY FROM 15/2211 UTC SHOWS A LARGE PLUME OF ELEVATED LEVELS OF SULFUR DIOXIDE FROM 02S TO 03N BETWEEN 91W AND 112W. EXPOSURE TO SULFUR DIOXIDE GAS CAN BE DANGEROUS... CAUSING IRRITATION TO EYES AND SKIN. ELSEWHERE...THE QUIKSCAT PASS FROM 1122 UTC REVEALED WINDS DOWNWIND OF THE GULF OF PAPAGAYO TO 25 KT THIS MORNING. THE SUBSEQUENT ASCAT PASS AT 1520 UTC MISSED THE CORE AREA OF WINDS...BUT DID MANAGE TO ENCOUNTER THE WESTERN EDGE OF THE WIND SWATH NEAR 10N90W WHERE WINDS WERE REPORTED TO 20 KT. THE 20 KM NAM FORECAST KEEPS WINDS ABOVE 20 KT HERE FOR THE NEXT FEW DAYS. SINCE IT HAS CAPTURED THE EVENT WHILE THE GFS IS CURRENTLY TOO WEAK...THE FORECAST RELIES ON THE STRONGER NAM. SCATTERED MODERATE CONVECTION CAN BE FOUND WITHIN 45 NM N AND 120 NM S OF THE ITCZ AXIS FROM 127W TO 135W IN A REGION OF UPPER LEVEL DIFFLUENCE WHERE A PORTION OF THE 50 KT WESTERLY UPPER JET ALONG 01N IS DIVERTED NORTHWARD UPSTREAM OF AN UPPER LEVEL ANTICYCLONE CENTERED NEAR 07N115W. THERE IS ALSO RELATIVELY STRONG LOW LEVEL CONVERGENCE HERE ALONG THE ITCZ WHERE 20 TO 25 KT NE WINDS ARE MEETING UP WITH 15 TO 20 KT E TO SE FLOW. TRADE WINDS...NE TO E FLOW IS CURRENTLY IN THE 20 TO 25 KT RANGE PRIMARILY W OF 125W ACCORDING TO THE 1838 TO 1844 UTC ASCAT PASSES. TRADES SHOULD SPREAD EASTWARD OVER THE NEXT 24 HOURS AS THE RIDGE AXIS STRENGTHENS AS SHIFTS SLIGHTLY EASTWARD. $$ SCHAUER CLARK