000 AXPZ20 KNHC 181606 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC THU SEP 18 2008 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1545 UTC. ...TROPICAL WAVES... TROPICAL WAVE ALONG 89W N OF 07N TO ACROSS WESTERN HONDURAS AND TO JUST E OF THE YUCATAN PENINSULA IS MOVING W ABOUT 13 KT. SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 120 NM W OF THE WAVE. ISOLATED MODERATE CONVECTION IS WITHIN 60 NM OF THE WAVE OVER WESTERN HONDURAS AND BELIZE. TROPICAL WAVE ALONG 99W FROM 5N-15N IS MOVING W 10-15 KT. A 1011 MB LOW IS IN BETWEEN BOTH WAVES NEAR 11N92W. BOTH OF THESE FEATURES ARE PART OF A LARGE AND DISORGANIZED AREA OF SCATTERED MODERATE TO STRONG CONVECTION THAT EXTENDS FROM 6N-14N BETWEEN 92W-102W. FIRST VISIBLE SATELLITE IMAGERY SHOWS BROAD CYCLONIC TURNING OF THE LOW CLOUD FIELD WITH THE ITCZ AXIS SERVING AS THE FOCAL POINT OF THIS AREA. QUIKSCAT DATA FROM THIS MORNING REVEALED THE CYCLONIC TURNING TO BE RATHER ELONGATED AS WELL ALONG THE ITCZ. SOME SLOW DEVELOPMENT MAY OCCUR WITH THIS AREA OVER THE NEXT COUPLE OF DAYS AS IT DRIFTS WESTWARD. TROPICAL WAVE ALONG 119W FROM 6N TO 16N IS MOVING W 10 KT. A QUIKSCAT PASS FROM AROUND 1330 UTC THIS MORNING SHOWED A WEAK LOW LEVEL CYCLONIC CIRCULATION ON THE WAVE AXIS NEAR 11N119W. ONLY ISOLATED WEAK CONVECTION IS NOTED WITHIN 60 NM OF THE LOW...AND WITHIN 120 NM E OF THE WAVE. OTHER ISOLATED WEAK CONVECTION IS WITHIN 60-90 NM OF THE WAVE AXIS IN THE VICINITY OF THE ITCZ AXIS. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 10N86W TO 11N91W TO 10N101W TO 8N110W TO 8N120W TO 10N127W TO 10N140W. SCATTERED STRONG CONVECTION IS WITHIN 60 NM S OF THE AXIS BETWEEN 121W-124.5W. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM EITHER SIDE OF THE AXIS BETWEEN 124.5W-128W. ...DISCUSSION... E OF 130W... MID/UPPER LEVEL ANTICYCLONIC CIRCULATION IS NEAR 22N118W WITH A RIDGE SW TO 20N130W...AND ANOTHER RIDGE NNE TO N OF THE AREA AT 32N117W AND CONTINUING N TO A CREST OVER THE NW UNITED STATES. A PRONOUNCED ANTICYCLONIC CIRCULATION IS CENTERED OVER EASTERN MEXICO NEAR 21N97W WITH A RIDGE W TO 20N108W. MID/UPPER LEVEL TROUGH MOVING E 20 KT EXTENDS FROM THE CENTRAL GREAT PLAINS SW TO 28N105W TO NW MEXICO NEAR 24N108W... AND TO 21N109W. A DEEP LAYERED TROUGH IS JUST NW OF THE AREA MOVING EWD...AND IS FORECAST TO MOVE INTO THE WESTERN UNITED STATES WITHIN THE NEXT 48 HOURS. STRONG UPPER LEVEL EASTERLY FLOW IS EVIDENT TO THE S OF THE ANTICYCLONE OVER MEXICO SPREADING UPPER LEVEL MOISTURE WESTWARD TO 112W. MODERATE TO STRONG SUBSIDENCE COVERS THE AREA PRIMARILY NW OF A LINE FROM 24N107W TO 21N117W TO 17N130W. AT THE SURFACE...A 1020 MB HIGH IS NEAR 20N128W WITH A RIDGE SE TO 22N114W. WEAK HIGH PRES COVERS THE AREA N OF 18N W OF 115W. A QUIKSCAT PASS FROM NEAR 1200 UTC THIS MORNING SHOWED N WINDS OF 20-30 KT THROUGH THE GULF OF TEHUANTEPEC WITH SEAS POSSIBLY UP TO 9 FT. SCATTERED TO BROKEN STRATOCUMULUS CLOUDS MOVING SW WITH POSSIBLE ISOLATED SHOWERS ARE LOCATED FROM 19N-27N BETWEEN 125W-130W. AN INVERTED MID/UPPER LEVEL TROUGH MOVING W 15 KT IS OUT AHEAD OF THE TROPICAL WAVE ALONG 119W IN THE AREA OF THE ITCZ FROM 7N-12N BETWEEN 124W-128W. IT IS ENHANCING ITCZ CONVECTION BETWEEN 124W-128W. W OF 130W... THE DEEP LAYERED TROUGH MENTIONED UNDER E OF 130W EXTENDS SW THROUGH 32N135W TO 27N130W TO W OF THE AREA AT 25N140W. ITS SURFACE COLD FRONT IS JUST ENTERING THE FAR NW CORNER OF THE AREA. BROKEN LOW AND MID LEVEL CLOUDS WITH WIDELY SCATTERED SHOWERS ARE ALONG AND WITHIN 90 NM SE OF THE FRONT. THE TROUGH IS FORECAST TO MOVE E OF THE AREA IN ABOUT 36 HOURS...WHILE THE SURFACE COLD FRONT WEAKENS AND BECOMES A SHEAR AXIS AS IT SKIRTS ALONG 31N/32N THROUGH SAT. THE WESTERN EXTENSION OF THE MID/UPPER LEVEL ANTICYCLONE EXTENDS WSW TO 19N140W. BROAD UPPER LEVEL SW FLOW IN A CONFLUENT PATTERN IS OBSERVED TO THE NW OF THE RIDGE AND S OF THE TROUGH WITH AMPLE MODERATE TO STRONG SUBSIDENCE WITH ASSOCIATED DRY STABLE AIR INHIBITING ANY DEEP CONVECTION FROM OCCURRING IN THAT PORTION OF THE AREA. LIMITED UPPER LEVEL MOISTURE ORIGINATING FROM THE ITCZ IS SLOWLY SPREADING NNE AROUND THE WESTERN PERIPHERY OF THE MID/UPPER LEVEL RIDGE SE OF A LINE FROM 20N130W TO 13N140W...AND THIS IS MOSTLY BEING INITIATED BY A WEAK SURFACE TROUGH DISSECTING THE ITCZ ALONG 133W FROM 9N-14N AND MOVING W 5-10 KT. $$ AGUIRRE