000 AXPZ20 KNHC 150954 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC TUE AUG 15 2006 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0945 UTC. SPECIAL FEATURES... .LOW PRES ANALYZED NEAR 13N111W 1009 MB IS ASSOCIATED WITH A TROPICAL WAVE LOCATED S OF 18N ALONG 110W. THE LOW IS ESTIMATED TO BE MOVING W NW AT 12 KT WHILE THE PARENT TROPICAL WAVE HAS MOVED W AT ABOUT 16 KT THE PAST 24 HOURS. A QUICK-SCAT PASS AROUND 0140Z CONFIRMS BROAD CYCLONIC TURNING WITH UNCONTAMINATED 20 KT WINDS WITHIN 300 NM N AND WITHIN 240 NM S SEMICIRCLES AND SEAS ESTIMATED TO 9 FT. CONVECTION OVER THE S SEMICIRCLE IS WITHIN THE ITCZ CONVECTION...DESCRIBED BELOW...BUT ISOLATED MODERATE TO STRONG CONVECTION IS OBSERVED N OF THE ITCZ ALONG A POOR 2/10 BANDING FEATURE...ALL WITHIN 330 NM N SEMICIRCLE OF THE ESTIMATED LLCC. THE LOW LEVEL CYCLONE IS MOVING W OF AN UPPER ANTICYCLONE CURRENTLY NEAR 17N105W BUT WITH AN UPPER RIDGE EXTENDING W OVER THE SURFACE LOW AND CONTRIBUTING TO THE CONVECTIVE FLARE UP. THE UPPER ANTICYCLONE IS FORECAST TO SHIFT NW TO NEAR 25N110W IN 24 HOURS AND TO NW OLD MEXICO IN 48 HOURS...WITH A RIDGE EXTENDING SW GENERALLY OVER THE FORECAST TRACK OF THE LOW. SO FOR NOW...I WILL CONSERVATIVELY MOVE THE CYCLONE W NW AT 12 KT DROPPING THE PRESSURE 2 MB EVERY 24 HOURS AND BUILDING A 20 TO 25 KT WIND FIELD OUT TO 360 NM BY 48 HOURS...WITH CONTINUED MENTION OF POSSIBLE TROPICAL CYCLONE DEVELOPMENT IN TEXT AND GRAPHICAL FORECASTS. ...TROPICAL WAVES... TROPICAL WAVE ALONG 95W MOVED W 15 KT THE PAST 24 HOURS. A N TO S LINE OF CONVECTION FLARED OVER THE ISTHMUS OF TEHUANTEPEC THE PAST FEW HOURS AND HAS MAINTAINED IDENTITY AS IT SHIFTS W. TROPICAL WAVE ALONG 126W HAS MOVED W 13 KT THE PAST 24 HOURS. THE WAVE HAS STRETCHED THE ITCZ N BETWEEN 120W AND 132W. CONVECTION ENHANCED WITHIN 150 NM W OF THE WAVE FROM 7N TO 14N. TROPICAL WAVE ALONG 140W HAS MOVED W 12 KT THE PAST 24 HOURS. CONVECTION ENHANCED ALONG THE WAVE AT 10N. ...ITCZ... ITCZ AXIS ALONG 8N80W 9N86W 8N102W 12N110W 13N122W 9N130W 11N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED N OF 5N BETWEEN 81W AND 87W AND WITHIN 120 NM EITHER SIDE OF LINE ALONG 10N101W 13N124W 10N140W. ...DISCUSSION... AN UPPER ANTICYCLONE IS NEAR 19N132W WITH A RIDGE EXTENDING NW ALONG 26N134W TO WELL BEYOND 32N140W. UPPER MOISTURE ORIGINATING FROM ITCZ CONVECTION BETWEEN 133W AND 150W IS ADVECTED NE UNDER THE RIDGE WITH THE NE MOISTURE BOUNDARY CURRENTLY ALONG A LINE FROM 33N133W TO 24N130W. A SHORTWAVE TROUGH HAS ITS AXIS ALONG 32N124W THROUGH A CYCLONE AT 25N123W TO A BASE NEAR 18N125W. VERY DRY UPPER AIR IS NOTED ALONG A LINE FROM 36N119W TO TO 30N125W WITH GENERALLY DRY UPPER AIR NOTED ELSEWHERE IN THE SUBTROPICS BETWEEN 129W AND 110W. MODELS MOVE THIS TROUGH E A TAD TODAY...THEN STALL IT THROUGH THE NEXT 48 HOURS AS THE UPPER ANTICYCLONE NEAR 17N105W SHIFTS NW AND BLOCKS ITS EASTWARD PROGRESSION...ALL MENTIONED IN SPECIAL FEATURE PARAGRAPH ABOVE. UPPER DEBRIS MOISTURE ORIGINATING FROM ITCZ CONVECTION BETWEEN 112W AND 110W IS ADVECTED N UNDER THE UPPER ANTICYCLONE AT 17N105W AND CONTINUE N OVER WRN OLD MEXICO AND EVENTUALLY ENE ACROSS THE DESERT SW OF CONUS INTO AN UPPER CYCLONE OVER CENTRAL TEXAS. AN WEAK UPPER RIDGE EXTENDS W ACROSS CENTRAL AMERICA INTO THE TROPICAL E PAC TO NEAR 14N90W. GAP WINDS...A SHIP REPORT AND A LATE AFTERNOON QUICK SCAT PASS CONFIRM ENE 20 KT WINDS IN...AND DOWNSTREAM OF THE GULF OF PAPAGAYO. GUIDANCE SUGGESTS ELY 20 KT SURGES WILL CONTINUE FOR ABOUT ANOTHER 36 HOURS BEFORE GRADIENT RELAXES...BUT I NOTICE THAT GRADIENT CONTINUES UPSTREAM IN W CARIBBEAN SO ITS LIKELY THAT 20 KT SURGES WILL CONTINUE THROUGH END OF WEEK. $$ NELSON