000 AXPZ20 KNHC 162136 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC THU APR 16 2009 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1945 UTC. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 05N77W TO 07N89W TO 05N103W TO 07N116W TO 05N140W. SCATTERED MODERATE CONVECTION CAN BE FOUND WITHIN 180 NM S OF AXIS FROM 89W TO 94W. ...DISCUSSION... N OF 20N... THE TIGHT PRESSURE GRADIENT BETWEEN A 1031 MB HIGH CENTERED NEAR 32N130W AND BROAD LOW PRES OVER THE WESTERN ROCKIES AND GREAT BASIN IS PRODUCING A SWATH OF NW WINDS TO 25 KT WITHIN 300 NM W OF THE BAJA PENINSULA COAST N OF 25N. THESE WINDS ARE EXPECTED TO GRADUALLY DIMINISH AS HIGH PRES N OF AREA WEAKENS AND RETREATS FARTHER N. NW WINDS UP TO 25 KT ARE ALSO NOTED THE GULF OF CALIFORNIA N OF 27N ACCORDING TO THE 1242 UTC QUIKSCAT PASS AND CONFIRMED BY THE 1638 UTC ASCAT PASS. MODEL GUIDANCE INDICATES THAT WINDS WILL SHIFT FURTHER SOUTH OVER THE NEXT 24 HOURS. SEAS ARE ANALYZED UP TO 11 FT OFF THE BAJA PENINSULA COASTLINE WITH NW SWELL. CONDITIONS SHOULD STEADILY SUBSIDE OVER THE NEXT FEW DAYS AS WINDS RELAX IN THIS REGION. S OF 20N... WHILE THE LA CUMBRE VOLCANO ON ISLA FERNANDINA IN THE GALAPAGOS ISLANDS LOCATED AT 00.4S91.5W CONTINUES TO ERUPT...THE GOVERNMENT OF ECUADOR REPORTS THAT THE RESULTING PLUME CONTAINS VAPOR AND GASES WITH NO SIGNIFICANT ASH. THE WASHINGTON VAAC HAS DISCONTINUED ASHFALL ADVISORIES. HOWEVER...MARINERS SHOULD STILL EXERCISE CAUTION AS GASES...INCLUDING SULFUR DIOXIDE...EXTEND AS MUCH AS 1200 NM TO THE W OF THE VOLCANO. NASA/OMI IMAGERY FROM 1758 UTC SHOWS ELEVATED LEVELS OF SULFUR DIOXIDE IN THE AREA FROM 02S AND 03N BETWEEN 91W AND 112W. EXPOSURE TO THIS GAS CAN BE DANGEROUS...CAUSING IRRITATION TO EYES AND SKIN. GAP WINDS... NE WINDS OF 20 KT CONTINUE TO FUNNEL THROUGH THE GULF OF PAPAGAYO. THIS FLOW SHOULD CONTINUE TO PULSE OVER THE NEXT FEW DAYS...ESPECIALLY IN THE EARLY MORNING HOURS WHEN DRAINAGE FLOW IS AT A MAXIMUM. TRADE WINDS... THE QUIKSCAT PASS FROM AROUND 1420 UTC SHOWED EASTERLY TRADES TO 25 KT ACROSS A LARGE PORTION OF THE FORECAST AREA N OF THE ITCZ W OF ABOUT 116W. BY FRI NIGHT AND SAT THE SURFACE HIGH TO THE NORTH IS EXPECTED TO WEAKEN...MOVE FARTHER N...AND SHIFT THE RIDGE AXIS TO THE WEST OVER FORECAST WATERS. THIS SHOULD ALLOW THE TRADES TO DIMINISH IN SPEED AND AREA. CONVECTION... SCATTERED MODERATE CONVECTION CAN BE FOUND WITHIN 75 NM OF LINE FROM 12N107W TO 05N137W. THIS CONVECTION COINCIDES WITH AN ELONGATED REGION OF BROAD UPPER LEVEL DIFFLUENCE WITH SOUTHEASTERLY FLOW 40 TO 50 KT N OF THE AXIS AND NORTHEASTERLY TO EASTERLY FLOW AT 20 TO 30 KT S OF THE AXIS. THE CONVECTION IS IN A REGION OF STRONG LOW LEVEL CONVERGENCE BETWEEN 25 KT TRADE WINDS TO THE NORTH AND 10 TO 15 KT EASTERLY WINDS TO THE SOUTH ACCORDING TO THE 1418 UTC QUIKSCAT PASS AND IT LIES WITHIN A POOL OF LOW TO MID LEVEL MOISTURE WITH PRECIPITABLE WATER VALUES IN THE 2.0 TO 2.25 INCH RANGE. THIS AXIS IS EXPECTED TO GRADUALLY SHIFT WESTWARD OVER THE NEXT DAY OR TWO. SCATTERED MODERATE CONVECTION CAN ALSO BE FOUND WITHIN 180 NM S OF THE ITCZ AXIS FROM 89W TO 94W IN A REGION OF WEAK UPPER LEVEL DIFFLUENCE IN THE REAR RIGHT QUADRANT OF A JET MAX ON THE LEADING EDGE OF AN UPPER LEVEL TROUGH WHICH EXTENDS FROM CUBA SOUTHWESTWARD THROUGH NICARAGUA AND HONDURAS INTO THE PACIFIC. THIS TROUGH IS EXPECTED TO DISSIPATE AND THE JET MAX WILL CONTINUE EASTWARD THROUGH THE CARIBBEAN. CONVECTION IS EXPECTED TO DIMINISH OVER THE NEXT FEW HOURS HERE AS A RESULT. $$ SCHAUER CLARK