000 AXPZ20 KNHC 290344 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC SAT AUG 29 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 0315 UTC. ...SPECIAL FEATURES... TROPICAL DEPRESSION THIRTEEN E HAS FORMED NEAR 13.8N 101.9W AT 0300 UTC AUG 29. MAXIMUM SUSTAINED WINDS ARE 30 KT WITH GUSTS TO 40 KT. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1007 MB. THE DEPRESSION IS MOVING SLIGHTLY N OF DUE W...OR 280 DEG...AT 11 KT. CURRENTLY STRONG CONVECTION HAS BURST WITHIN 60 NM OF CENTER. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS ALSO NOTED IN A CLUSTER WELL N OF CENTER...WITHIN 90 NM OF 16N100W. SIMILAR CONVECTION IS ALSO NOTED WITHIN 15 NM OF 13N104W AND 16N104W. THE DEPRESSION IS EXPECTED TO STRENGTHEN TO A TROPICAL STORM LATE TONIGHT TRACK NW STRENGTHENING TO A HURRICANE LATE SUN. REFER TO NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP3/WTNT23 KNHC FOR ADDITIONAL INFORMATION. ...TROPICAL LOWS... .BROAD LOW PRES NEAR 12N120W IS ANALYZED AT 1008 MB. WINDS HAVE INCREASED TO 20 TO 25 KT WITHIN ROUGHLY 360 NM SE OF CENTER AND WITHIN 180 NM NW OF CENTER. CURRENTLY SCATTERED MODERATE ISOLATED STRONG CONVECTION IS ATTEMPTING TO BAND WITHIN 240 NM OVER NW SEMICIRCLE OF THE CENTER AND TROPICAL CYCLONE FORMATION IS POSSIBLE FOR THE NEXT DAY OR SO THEN THE UPPER LEVEL ENVIRONMENT BECOMES LESS FAVORABLE. .A SMALL SURFACE LOW PRES FORMED THIS AFTERNOON NEAR 17N133W AND IS ESTIMATED AT 1011 MB. THE LAST ASCAT PASS INDICATED NE TO E WINDS AT 20 TO 25 KT WITHIN 150 NM OVER THE N SEMICIRCLE WITH SEAS TO 8 FT. THIS LOW IS EXPECTED TO WEAKEN TO AN OPEN TROUGH AND QUICKLY DISSIPATE AS A SURFACE RIDGE BUILDS SE ACROSS THE AREA THIS WEEKEND. ...TROPICAL WAVES... A TROPICAL WAVE IS N OF 05N ALONG 86W AND IS MOVING W AT 15 KT. SCATTERED MODERATE TO STRONG CONVECTION IS NOTED TO THE N OF 09N ALONG THE WAVE AXIS. THE WAVE IS CURRENTLY MOVE UNDER AN AREA OF UPPER DIFFLUENCE...RIGHT ALONG THE EASTERN EDGE OF AN UPPER ANTICYCLONE AND ALONG THE W EDGE OF UPPER TROUGH. THE WAVE WILL MOVE UNDER THE UPPER RIDGE OVER THE NEXT FEWS DAYS WITH THE POSSIBILITY OF AN INCREASE IN CONVECTION LATER THIS WEEKEND... SIMILAR TO THE SITUATION OF THE NEWLY FORMED TROPICAL DEPRESSION TO ITS W. ...ITCZ... THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS ALONG 07N77W TO 10N87W TO 08N95W TO 13N114W TO 08N125W TO 12N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED N OF 05N BETWEEN 81W AND 89W. SCATTERED MODERATE CONVECTION IS NOTED FROM 06N TO 11N BETWEEN 89W AND 108W...AND WITHIN 150 NM EITHER SIDE OF A LINE FROM 11N122W TO 07N127W AND A LINE FROM 10N137W TO 06N140W. ...DISCUSSION... AN UPPER ANTICYCLONE NEAR IS CENTERED NEAR 24N133W HAS A RIDGE SW TO NEAR 14N145W AND A RIDGE E TO NEAR 27N123W. A SECOND UPPER ANTICYLONE IS NEAR 31N119W WITH A RIDGE S TO A SHARP CREST AT 27N120W. AN UPPER CYCLONE IS CENTERED NEAR 34N127W TRAILING AN UPPER TROUGH SW ALONG 30N130W TO 29N140W. ANOTHER UPPER CYCLONE IS IS AT 21N115W WITH A TROUGH EXTENDING S TO NEAR 05N120W. UPPER DIFFLUENCE IS ENHANCING CONVECTION OVER THE LOW PRES NEAR 12N120W WITH MOST OF THE DEBRIS MOISTURE ADVECTED SW MERGING WITH ITCZ DEBRIS MOISTURE NEAR 08N124W. THE UPPER LEVELS ARE DRY N OF 18N W OF 110W. AN UPPER ANTICYCLONE IS NEAR 17N96W WITH ITS ENVELOPE OF ANTICYCLONIC FLOW EXTENDING S OVER THE TROPICAL PACIFIC BETWEEN 84W AND 108W...AND IS ENHANCING CONVECTION ASSOCIATED WITH THE TROPICAL DEPRESSION. ELSEWHERE AT THE SURFACE...1020 MB HIGH PRES IS NEAR 29N138W BUT IS EXPECTED TO DISSIPATE AS A STRONGER RIDGE NW OF THE AREA BRIDGES THROUGH A FRONT THAT HAS STALLED JUST NW OF THE DISCUSSION AREA. THE REMNANTS OF IGNACIO ARE AT 29N129W AND EXPECTED TO MEANDER AND GRADUALLY SPIN DOWN OVER THE NEXT FEW DAYS AS HIGH PRES BUILDS FROM THE W. GAP WINDS...EXPECTING NE TO E WINDS 15 TO 20 KT TO PULSE ACROSS THE AND JUST DOWNSTREAM OF THE GULF OF PAPAGAYO FOR THE NEXT FEW DAYS. $$ NELSON