000 AXPZ20 KNHC 130245 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC THU JUN 13 2013 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0230 UTC. ...TROPICAL WAVES... A TROPICAL WAVE EXTENDS ALONG 81W N OF 05N ACROSS WESTERN PANAMA INTO THE CARIBBEAN SEA TO NEAR 14N. THE WAVE IS INTERACTING WITH THE MONSOON TROUGH...AS NOTED BY A LARGE SWATH OF SW SURFACE FLOW OVER THE EASTERN PACIFIC. IN ADDITION...AN UPPER LEVEL TROUGH EXTENDING ACROSS THE SW CARIBBEAN IS ALSO INTERACTING WITH THE TROPICAL WAVE AND MONSOON TROUGH TO ENHANCE THE CONVECTION ASSOCIATED WITH THE WAVE. LATEST IR SATELLITE IMAGERY SHOWS SCATTERED MODERATE TO ISOLATED STRONG CONVECTION OVER THE SW CARIBBEAN MAINLY E OF THE WAVE AXIS WHILE CONVECTION HAS DIMINISHED OVER THE EPAC IN ASSOCIATION WITH THIS FEATURE. WAVE GROWTH IS SUPPORTED BY FRESH TO STRONG E FLOW IN THE MID LEVELS OF THE ATMOSPHERE. THESE FAVORABLE CONDITIONS WILL PERSIST THROUGH 48 HOURS AS THE WAVE MOVES INTO THE EASTERN PACIFIC TOWARD 90W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH ALONG 10N86W TO 09N100W TO 1010 MB LOW PRES NEAR 12N114W TO A SECOND 1010 MB LOW PRES NEAR TO 12N118W TO 11N125W THEN ITCZ AXIS TO BEYOND 08N140W. SCATTERED MODERATE TO ISOLATED STRONG WITHIN 90 NM S OF ITCZ AXIS W OF 137W. NO SIGNIFICANT CONVECTION ELSEWHERE. ...DISCUSSION... A 1010 MB LOW PRES REMAINS EMBEDDED WITHIN THE MONSOON TROUGH NEAR 12N114W. A TROUGH EXTENDS FROM THE LOW TO NEAR 17N109W. THE 1940 UTC OSCAT PASS REVEALED THE WIND SHIFT ASSOCIATED WITH THE TROUGH AXIS. SCATTERED MODERATE CONVECTION IS NEAR THE NORTHERN END OF THE TROUGH AXIS COVERING FROM 16N TO 19N BETWEEN 109W AND 112W. A SWIRL OF MAINLY LOW CLOUDS IS RELATED TO THE LOW CENTER. THIS SYSTEM WILL MIGRATE W THROUGH 48 HOURS INTO LESS FAVORABLE AREAS BOTH IN TERMS OF AVAILABLE MOISTURE AND UPPER SUPPORT. FARTHER WEST...A SECOND WEAK LOW PRES IS NOTED NEAR 12N118W AND IS ALSO ALONG THE MONSOON TROUGH. STRONG HIGH PRES SITUATED NW OF AREA NEAR 40N141W EXTENDS A RIDGE SE OVER THE N WATERS TO NEAR 20N110W. THIS SYSTEM IS PRODUCING NE WINDS OF 20 KT OVER THE NW CORNER OF THE FORECAST AREA PER THE MOST RECENT SCATTEROMETER PASSES. TRADE WINDS OF 15- 20 KT ARE ALONG THE SOUTHERN PERIPHERY OF THE RIDGE N OF THE ITCZ AND W OF 132W. THIS HIGH PRES IS FORECAST TO MOVE TOWARDS THE S DURING THE NEXT 24 HOURS AND COULD BRIEFLY INCREASE WINDS TO 25 KT ACROSS THE NW WATERS...PARTICULARLY N OF 26N W OF 130W...LATER TONIGHT INTO THU MORNING. ALOFT...A TROUGH/RIDGE/TROUGH PATTERN DOMINATES MOST OF THE FORECAST AREA N OF 20N W OF 110W WHERE MODERATE TO STRONG UPPER LEVEL SUBSIDENCE PREVAILS. AN ELONGATED UPPER CYCLONE IS OVER SOUTHERN BAJA CALIFORNIA WITH A TROUGH EXTENDING S TO ABOUT 17N116W. UPPER DIVERGENCE ALOFT BETWEEN THIS FEATURE AND AN UPPER ANTICYCLONE CENTERED OVER SOUTH-CENTRAL MEXICO IS SUPPORTING THE WEAK SURFACE LOW PRES AREAS PREVIOUSLY MENTIONED. AN ANTICYCLONE LOCATED NEAR 19N142W EXTENDS A RIDGE OVER THE WEST CENTRAL WATERS TO NEAR 17N128W. EASTERLY WINDS ALOFT COVER THE REMAINDER OF THE DISCUSSION AREA...MAINLY E OF 110W. THESE WINDS ARE TRANSPORTING ABUNDANT MID TO UPPER LEVEL MOISTURE. N TO NE SWELL OF 8 TO 10 FT ASSOCIATED WITH WINDS TO GALE FORCE OFF THE COAST OF CENTRAL CALIFORNIA ARE PROPAGATING OVER THE WATERS NW OF LINE FROM 30N126W TO 19N140W...AS NOTED IN THE MOST RECENT ALTIMETER PASS. LONG PERIOD CROSS EQUATORIAL SW SWELLS... WITH WAVE PERIOD OF 15-16 SECONDS WILL CONTINUE TO IMPACT THE FORECAST WATERS E OF 115W. A NEW SW SWELL TRAIN WITH LEADING EDGE PERIOD OF 18-19 SECONDS IS ALREADY AFFECTING THE SOUTH CENTRAL WATERS AND IS FORECAST TO REACH THE COASTLINE THU NIGHT. $$ GR