000 AXPZ20 KNHC 182136 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC THU SEP 18 2008 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2100 UTC. ...TROPICAL WAVES... TROPICAL WAVE ALONG 90W N OF 07N TO ACROSS GUATEMALA AND THE NORTHERN YUCATAN PENINSULA IS MOVING W ABOUT 10 KT. SCATTERED MODERATE CONVECTION IS WITHIN 180 NM E OF THE WAVE FROM 11N-13N. THIS WAVE WAVE WILL MOVE CLOSER TO THE AREA OF DISTURBED WEATHER DESCRIBED IN THE PARAGRAPH BELOW OVER THE NEXT 36-48 HOURS. TROPICAL WAVE ALONG 100W FROM 5N-15N IS MOVING W 10-15 KT. THIS WAVE IS PART OF A LARGE AND DISORGANIZED AREA OF SCATTERED MODERATE TO STRONG CONVECTION THAT EXTENDS FROM 6N-14N BETWEEN 92W-104W. VISIBLE SATELLITE IMAGERY CONTINUES TO SHOW BROAD CYCLONIC TURNING OF THE LOW CLOUD FIELD WITH THE ITCZ AXIS SERVING AS THE FOCAL POINT OF THIS AREA. CONVECTION WITHIN THIS AREA IS UNDER THE INFLUENCE OF STRONG UPPER EASTERLY SHEAR SO THE AREA WILL REMAIN RATHER ELONGATED WITH ONLY SLOW DEVELOPMENT EXPECTED OVER THE NEXT COUPLE OF DAYS AS IT DRIFTS WESTWARD. TROPICAL WAVE ALONG 119W FROM 6N TO 16N IS MOVING W 10 KT. VISIBLE SATELLITE IMAGERY FROM THROUGHOUT THE DAY SHOWS A WEAK LOW LEVEL CYCLONIC CIRCULATION ON THE WAVE AXIS NEAR 10N119W ...BUT IS BECOMING ILL-DEFINED WITH TIME. ONLY ISOLATED WEAK CONVECTION IS NOTED WITHIN 30-60 NM OF THE LOW...AND WITHIN 120 NM E OF THE WAVE. OTHER ISOLATED WEAK CONVECTION IS WITHIN 60 NM OF THE WAVE AXIS IN THE VICINITY OF THE ITCZ AXIS. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 10N86W TO 10N100W TO 8N110W TO 9N120W TO 8N125W TO 11N132W TO 9N140W. SCATTERED MODERATE CONVECTION IS WITHIN 180 NM S OF THE AXIS BETWEEN 122W-128W. ...DISCUSSION... E OF 130W... AN ELONGATED E TO W MID/UPPER LEVEL ANTICYCLONE IS LOCATED NEAR 22N117W MOVING E NEAR 10 KT. A RIDGE EXTENDS SW TO W OF THE AREA AT 18N130W...WITH 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 E OF THE AREA OVER THE WRN BAY OF CAMPECHE NEAR 19N96W WITH A RIDGE WNW TO 20N106W. WEAK MID/UPPER LEVEL TROUGHING IS PRESENT OVER NRN MEXICO N OF 25N WITH MEAN AXIS FROM 32N105W TO 21N107W. A DEEP LAYERED TROUGH IS JUST N OF THE FAR NW PART OF THE AREA RAPIDLY MOVING EWD. THE TROUGH IS FORECAST TO MOVE INTO THE WESTERN UNITED STATES WITHIN THE NEXT 48 HOURS. STRONG UPPER LEVEL EASTERLY FLOW...WHICH IS RESPONSIBLE FOR CREATING THE EASTERLY OVER THE AREA OF DISORGANIZED CONVECTION MENTION ABOVE WITH THE WAVE ALONG 100W...IS EVIDENT TO THE S AND SW OF THE ANTICYCLONE OVER THE WRN BAY OF CAMPECHE AND SPREADING UPPER LEVEL MOISTURE WESTWARD TO 114W S OF 14N. MODERATE TO STRONG SUBSIDENCE COVERS THE AREA PRIMARILY NW OF A LINE FROM 24N107W TO 17N115W TO 12N130W. AT THE SURFACE...A 1020 MB HIGH IS NEAR 28N128W WITH A RIDGE SE TO 25N122W. 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. THESE WINDS ARE FORECAST TO DIMINISH TO LESS THAN 20 KT IN ABOUT 42 HOURS. SCATTERED TO BROKEN STRATOCUMULUS CLOUDS MOVING SW WITH POSSIBLE ISOLATED SHOWERS ARE LOCATED FROM 19N-28N BETWEEN 120W-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 9N-14N BETWEEN 127W-129W. IT IS ENHANCING ITCZ CONVECTION BETWEEN 124W-128W. W OF 130W... THE DEEP LAYERED TROUGH MENTIONED UNDER E OF 130W EXTENDS SW THROUGH 32N135W SW TO W OF THE AREA AT 25N140W. THE CORRESPONDING SURFACE COLD FRONT CLIPS THE FAR NW CORNER OF THE AREA FROM 32N137W TO 30N140W WHERE IT BECOMES STATIONARY WELL W OF THE DISCUSSION AREA. BROKEN LOW AND MID LEVEL CLOUDS WITH WIDELY SCATTERED SHOWERS ARE ALONG AND WITHIN 60 NM SE OF THE FRONT. THE DEEP LAYERED TROUGH IS FORECAST TO MOVE E OF THE AREA IN ABOUT 24-36 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 THAT DISSECTS THE ITCZ ALONG 133W FROM 9N-14N MOVING SLOWLY W. $$ AGUIRRE