000 AXPZ20 KNHC 200936 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC FRI JUN 20 2008 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 0915 UTC. ...TROPICAL WAVES... TROPICAL WAVE S OF 15N ALONG 101W MOVING W 10 TO 15 KT. LITTLE TO NO CONVECTION IS ASSOCIATED WITH THE WAVE...AND THE WAVE IS EXTRAPOLATED FORWARD. ...ITCZ... INTERTROPICAL CONVERGENCE ZONE 06N77W TO 09N88W TO 10N101W TO 13N110W TO 12N122W TO 08N130W TO 08N140W. SCATTERED MODERATE CONVECTION IS WITHIN 150 NM E OF LINE FROM 07N95W TO 13N98W. SCATTERED MODERATE CONVECTION IS WITHIN 90 NM EITHER SIDE OF AXIS BETWEEN 110W AND 112W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS WITHIN 240 NM S OF AXIS FROM 112W TO 122W. ...DISCUSSION... BETWEEN FRI LAST WEEK AND WED THIS WEEK A STRONG PRESSURE GRADIENT BETWEEN CLIMATOLOGICAL LOW PRESSURE OVER THE DESERT SW AND SURFACE HIGH PRESSURE OVER THE NE PACIFIC WAS GENERATING NEAR-CONSTANT GALE CONDITIONS OFFSHORE THE CALIFORNIA AND OREGON COASTS. ALTHOUGH THE GALE EVENT IS NOW OVER AND WINDS ARE CONSIDERABLY LOWER...ASSOCIATED N TO NE SWELL TO NEAR 8 FT IS STILL ARRIVING OVER THE FAR NORTHERN WATERS N OF 29N BETWEEN 118W AND 130W. MOREOVER...THE N TO NE SWELL CONTINUES TO MIX WITH A NEARLY CONTINUOUS SUPPLY OF LONG PERIOD SW SWELL PROPAGATING OUT OF THE SOUTHERN HEMISPHERE. HOWEVER...MODEL GUIDANCE INDICATES THAT 8 FT NORTHERLY SWELL SHOULD DIMINISH ENTIRELY THIS MORNING ...WITH SEAS EXPECTED TO SUBSIDE FURTHER...DOWN TO 5 TO 7 FT W OF THE BAJA PENINSULA BY SAT. THE LULL IN WINDS AND SEAS SHOULD BE SHORT-LIVED THOUGH...SINCE A SHORTWAVE NOW OVER THE NE PACIFIC IS EXPECTED TO REACH THE WEST COAST AND MOVE INLAND OVER THE NW. AS THIS OCCURS...HIGH AND LOW PRESSURE IN THE SAME POSITIONS AS THE WEEK BEFORE...SHOULD RE-STRENGTHEN AND CAUSE NLY WINDS TO PICK UP AGAIN...BUT THIS TIME IN A MORE NARROW REGION OFFSHORE THE CALIFORNIA AND WESTERN BAJA CALIFORNIA COASTS. EXPECT SEAS TO BUILD TO AS HIGH AS 8 FT WITHIN 180 NM W OF THE BAJA CALIFORNIA COAST N OF 27N BY LATE SUN. OVER THE SOUTHERN WATERS LONG PERIOD SW SWELL PROPAGATING OUT OF THE SOUTHERN HEMISPHERE CONTINUES TO CROSS THE EQUATOR AND ENGULF MUCH OF THE TROPICAL EASTERN PACIFIC. AS A RESULT...A LARGE AREA OF 8 TO 9 FT SEAS PERSISTS...GENERALLY S OF 10N W BETWEEN 100W AND 126W. IN ADDITION TO THE SWELL...A 0306 UTC QUIKSCAT PASS SHOWED A NARROW REGION OF ENHANCED NERLY TRADES TO 20 KT ROUGHLY FROM 10N TO 13N W OF 135W...SUGGESTING THAT NE WIND WAVES ARE COMBINING WITH SW SWELL OVER THIS REGION. OVER THE NEXT FEW DAYS...NOAA WAVEWATCH III GUIDANCE SHOWS THE LARGE AREA OF SW SWELL GREATLY SHRINKING AND SUBSIDING...WITH THE AREA OF 8 FT SEAS S OF THE EQUATOR BY SAT MORNING. HOWEVER...NEWER SOUTHEASTERLY SWELL ALREADY PASSING THROUGH THE TROPICAL SOUTH PACIFIC IS EXPECTED TO ARRIVE OVER THE WATERS S OF 10N W OF 120W AND EXPAND EASTWARD LATER THIS WEEKEND...THOUGH WAVE HEIGHTS SHOULD STAY JUST BELOW 8 FT. ELSEWHERE...VISIBLE SATELLITE IMAGERY FROM LATE YESTERDAY AS WELL AS MORE RECENT LOW-LEVEL CLOUD-WIND VECTORS INDICATE THE PRESENCE OF A BROAD AND ELONGATED AREA OF LOW PRESSURE EMBEDDED WITHIN THE ITCZ ROUGHLY NEAR 11N122W...WHICH HAS BEEN MOVING W TO WNW AT 10 TO 15 KT THE LAST FEW DAYS. LIKE YESTERDAY... ASSOCIATED CONVECTION IS NEARLY NON-EXISTENT...EVEN THOUGH THE UPPER-LEVEL FLOW IS MORE DIFFLUENT THAN IT WAS YESTERDAY. FARTHER EAST...A 0124 UTC QUIKSCAT PASS REVEALED A SECOND... BETTER- ORGANIZED AREA OF LOW PRESSURE NEAR 12N110W...MARCHING W AT 10 TO 15 KT. ALTHOUGH ASSOCIATED CONVECTION WAS EARLIER INTERMITTENT AND DISORGANIZED...RECENT SATELLITE IMAGERY SHOWS SOME MARGINAL INCREASE IN ORGANIZATIONAL STRUCTURE. RECENT QUIKSCAT PASSES ALSO SHOWED A LARGE AREA OF ENHANCED CROSS- EQUATORIAL FLOW FEEDING INTO THIS SYSTEM FROM 110W TO 120W... POSSIBLY INDICATING THAT SOMETHING IS AFOOT. ALTHOUGH ELY VERTICAL WIND SHEAR IS LIGHT AND IS EXPECTED TO REMAIN LIGHT THE NEXT FEW DAYS...THE SYSTEM WILL GRADUALLY WILL FIND A GRADUAL DECREASE IN OCEANIC SEA SURFACE TEMPERATURES ON ITS WESTWARD TRACK WHICH COULD LIKELY LIMIT FURTHER DEVELOPMENT. REGARDLESS OF WHETHER THIS SYSTEM FORMS...THE ACTIVE PHASE OF THE MADDEN-JULIAN OSCILLATION /MJO/ IS NOW IN THE WESTERN PACIFIC AND WILL LIKELY PROPAGATE INTO THE CENTRAL AND EASTERN PACIFIC WITHIN A WEEK TO TEN DAYS...LIKELY ENHANCING THE POTENTIAL FOR TROPICAL CYCLONE DEVELOPMENT. FINALLY...STRONG TRADES IN THE CENTRAL AND EASTERN CARIBBEAN EARLIER THIS WEEK HAVE NOW SPREAD FARTHER WEST INTO THE WESTERN CARIBBEAN AND ARE CONTRIBUTING TO THE DEVELOPMENT OF A GAP WIND EVENT IN THE GULF OF PAPAGAYO. IN FACT...A 2344 UTC QUIKSCAT PASS FROM YESTERDAY ALREADY REVEALED THE PRESENCE OF 20 KT NE WINDS WITHIN 30 NM EITHER SIDE OF 11N E OF 86.5W. THE GAP WINDS SHOULD CONTINUE INCREASING AND EXPAND FARTHER DOWNSTREAM TODAY ...WITH NE 20 TO 25 KT WINDS POSSIBLE BY SAT MORNING. AS WINDS GRADUALLY EXPAND AND THE FETCH AREA INCREASES...EXPECT SEAS TO BUILD TO 8 OR 9 FT SAT AND POSSIBLY PEAK AROUND 10 FT BY SAT AFTERNOON. MODELS SHOW THE GAP WINDS PERSISTING INTO SUN BUT THEN GRADUALLY ABATING LATE SUN INTO MON. $$ KIMBERLAIN