000 AXPZ20 KNHC 202209 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC SUN AUG 20 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2145 UTC. ...SPECIAL FEATURES... TS HECTOR NEAR 20.4N 134.2W 995 MB AT 2100 UTC AUG 20 MOVING NW OR 305 DEG AT 9 KT. MAXIMUM SUSTAINED WINDS 50 KT GUSTS 60 KT. VISIBLE SATELLITE IMAGERY VERIFY THAT WLY SHEAR CONTINUES EXPOSING THE LOW LEVEL CENTER TO THE SW OF DISORGANIZED CONVECTION. CURRENTLY SCATTERED MODERATE TO STRONG CONVECTION IS NOTED WITHIN 120 NM OVER THE NE SEMICIRCLE. RAPID WEAKENING IS EXPECTED TONIGHT AS HECTOR ENCOUNTERS COLDER WATER...WIND SHEAR AND MORE STABLE AIR. HECTOR WILL LIKELY WEAKEN TO A TD ON MON AND DISSIPATE BY TUE. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP4/WTPZ24 KNHC FOR MORE DETAILS. LOW PRES HAS FORMED ALONG A TROPICAL WAVE LYING N TO S ALONG 100W. THE ESTIMATED CENTER IS NEAR 10N101W 1008 MB AND MOVING W 10 KT. BROAD CYCLONIC ROTATION CONTINUES WITH INTERMITTENT ATTEMPTS AT BANDING. AN UPPER ANTICYCLONE TO ITS NW NEAR 21N108W RIDGES SE ALONG THE CENTRAL AMERICAN PACIFIC COAST TO NEAR 14N90W WITH UPPER DIFFLUENCE OVER THE SURFACE LOW. THIS DIFFLUENCE EXTENDS ABOUT 500 NM TO W AND WILL SUPPORT CONTINUED DEVELOPMENT AS SEVERAL MODELS SUGGEST...THUS MENTION OF POSSIBLE TROPICAL CYCLONE DEVELOPMENT ADDED TO TEXT AND GRAPHICS. ...TROPICAL WAVES... A TROPICAL WAVE N OF 4N ALONG 82W IS ESTIMATED TO BE MOVING W AT 12 KT. ONLY A FEW CLUSTERS OF CONVECTION IS ENHANCED ALONG THE ITCZ IN THE PAC...BUT A LARGE CLUSTER IS NOTED ALONG THE WAVE IN THE SW CARIBBEAN NEAR 14N80W. A TROPICAL WAVE ALONG 123.5 FROM 3N TO 15N IS MOVING W AT AN ESTIMATED 12 KT. ALTHOUGH BROAD CYCLONIC TURNING IS NOTED ONLY SCATTERED SHOWERS ACCOMPANY THE WAVE WITHIN 60 NM OF ITS AXIS FROM 6N TO 12N. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 9N78W 12N100W 7N112W 15N132W 12N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED WITHIN 150 NM EITHER SIDE OF LINE 4N82W 13N97W 8N112W. SCATTERED MODERATE CONVECTION IS NOTED WITHIN 60 NM EITHER SIDE OF LINE 8N112W 8N126W AND LINE 14N134W 12N140W. ...DISCUSSION... A NEGATIVE TILT SHORTWAVE TROUGH LIES ALONG 32N129W 30N126W. A SECOND SHORTWAVE AS BECOME STATIONARY ALONG 33N118W THROUGH AN UPPER CYCLONE AT 23N116W AND ANOTHER AT 17N116W TO A BASE AT 10N116W. VERY DRY AIR IS NOTED ALONG THE TROUGH AXIS N OF 27N. AN ANTICYCLONE IS CENTER NEAR 18N124W AND RIDGES N TO A GENTLE CREST ALONG POINTS 27N132W 30N125W 25N120W...AND EFFECTIVELY SEPARATES THE TWO SHORTWAVE TROUGHS. THE TROUGH TO THE W APPEARS TO BE ERODING THE NW PERIPHERY OF THE RIDGE. ANOTHER ANTICYCLONE IS QUASI STATIONARY AREA NEAR 18N147W RIDGING E TO A CREST JUST W OF THE TS HECTOR AT 18N136W. A SMALL UPPER CYCLONE IS OBSERVED NEAR 19N98W WITH AN UPPER TROUGH EXTENDING E TO ANOTHER UPPER CYCLONE OVER THE CARIBBEAN NEAR 21N83W. UPPER MOISTURE...ORIGINATING FROM ITCZ CONVECTION THROUGHOUT THE DISCUSSION AREA AND FROM TS HECTOR...IS NOTED SE OF LINE 21N138W 30N121W. MODERATE DRY AIR UPPER IS NOTED NW OF THE SAME LINE. AT THE SURFACE...A RIDGE EXTENDS SE ALONG 32N132W TO 16N113W WITH NW WINDS SURGING TO 20 KT AND SEAS TO 8 FT OVER THE WATERS N OF 25N ALONG THE W COAST OF THE BAJA PENINSULA. GAP WINDS...ALTHOUGH QSCAT DATA NOT AVAILABLE...A PARTIAL SSMI PASS AND 2 SHIP REPORTS AT 1800 UTC INDICATE E WINDS TO 20 KT HAVE SURGED INTO THE GULF OF PAPAGAYO. MODELS SUGGEST THIS IS TEMPORARY THUS INTRODUCED INTO TEXT HIGH SEAS FOR ONLY THE INITIAL 6 HOURS. $$ NELSON