000 AXPZ20 KNHC 300918 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC THU JUL 30 2009 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 0900 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 91W N OF 04N MOVING W NEAR 20 KT. SCATTERED MODERATE TO STRONG CONVECTION HAS DEVELOPED ALONG THE WAVE N OF 12N BETWEEN 89W-92W...LIKELY ENHANCED BY UPPER DIFFLUENCE BETWEEN AN INVERTED UPPER TROUGH TO THE W AND AN UPPER RIDGE TO THE N. TROPICAL WAVE IS ALONG 117W FROM 08N TO 17N MOVING W 10 KT. SATELLITE IMAGES INDICATE A LESS DISTINCT AREA OF MID LEVEL CYCLONIC TURNING AS THE WAVE CONTINUES TO INTERACT WITH AN UPPER LEVEL LOW NEAR 15N122W. SCATTERED MODERATE CONVECTION IS CONFINED TO WITHIN 180 NM EITHER SIDE OF THE WAVE AXIS. DEVELOPMENT IS NOT EXPECTED OVER THE NEXT COUPLE OF DAYS AS THE WAVE MOVES IN TANDEM WITH THE UPPER LOW. AN AREA OF LOW PRESSURE IS GRADUALLY BECOMING BETTER DEFINED NEAR 11N IN ASSOCIATION WITH THE TROPICAL WAVE ALONG 137W. THE WAVE AND LOW ARE MOVING W NEAR 15 KT. CONVECTION HAS DEEPENED OVER THE PAST SEVERAL HOURS IN BROKEN CURVED BANDS N AND E OF THE CENTER. SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 300 NM W AND 180 NM E SEMICIRCLES OF THE LOW. A 0616 UTC ASCAT PASS INDICATED A CLOSED BUT ELONGATED SFC CIRCULATION. THIS FEATURE IS SITUATED IN AN AREA OF INCREASING ANTICYCLONIC FLOW ALOFT WHICH COULD FAVOR DEVELOPMENT. ...ITCZ... THE INTERTROPICAL CONVERGENCE ZONE IS ALONG THE LINE...09N79W 07N100W 12N115W 11N135W 10N140W. SCATTERED MODERATE TO STRONG CONVECTION IS FROM 05N TO 09N E OF 90W. SCATTERED MODERATE CONVECTION IS WITHIN 240 NM OF THE AXIS BETWEEN 114W AND 120W. ...DISCUSSION... MAIN AREA OF INTEREST ACROSS THE EAST PACIFIC REGION IS THE TROPICAL WAVE AND ASSOCIATED LOW NEAR 11N137W. A 0246 UTC QSCAT PASS MISSED THE CIRCULATION CENTER...BUT DOES SUGGEST 20-25 KT WINDS NEAR THE LOW. A BROADER AREA OF 20 KT TRADES EXIST FROM 12N-19N W OF 128W IN RESPONSE TO THE STEEPENED PRESSURE GRADIENT BETWEEN THE LOW AND THE SUBTROPICAL RIDGE. THIS LOW IS EXPECTED TO CONTINUE W AT 15 KT WITH THE 20-25 KT FLOW...OR POSSIBLY STRONGER...GRADUALLY SHIFTING W WITH IT. THE LOW WILL LIKELY CROSS 140W AROUND 18 UTC TODAY. DIFFLUENT UPPER FLOW OVER NORTHERN MEXICO HAS PRODUCED CLUSTERS OF MODERATE TO STRONG CONVECTION FROM 23N-28N GENERALLY ALONG THE SIERRA MADRE OCCIDENTAL. BESIDES FOR THIS AREA OF CONVECTION AND THE TROPICAL WAVES AND ITCZ RELATED CONVECTION...MUCH OF THE REMAINDER OF THE BASIN IS EXPERIENCING FAIR WEATHER. GAP WINDS... SCATTEROMETER DATA INDICATES SE 20 KT WINDS OVER THE GULF OF CALIFORNIA N OF 25N. THIS FLOW APPEARS TO BE DRIVEN BY THE TIGHTENED PRESSURE GRADIENT BETWEEN LOW PRESSURE OVER INTERIOR SRN CALIFORNIA AND HIGH PRESSURE OVER NW MEXICO. GFS AND NAM MODELS SHOW THESE FEATURES DAMPENING OVER THE NEXT 24 HOURS... ALLOWING THE ENHANCED WINDS TO DIMINISH. MODERATING TRADES ACROSS THE CARIBBEAN ARE RESULTING IN WEAKENED FLOW THROUGH THE GULF OF PAPAGAYO. A 0252 UTC ASCAT PASS REVEALED NE WINDS OF 15-20 KT IN THE GAP...BUT ITS RESOLUTION IS LIKELY INADEQUATE TO CAPTURE THE PEAK WIND OR DETAILED STRUCTURE. NWP MODELS AGREE IN DIMINISHING WINDS BELOW 20 KT WITHIN THE NEXT 36 HOURS. $$ CANGIALOSI