000 AXPZ20 KNHC 180959 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC SAT SEP 18 2010 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 0915 UTC. ...ITCZ... INTERTROPICAL CONVERGENCE ZONE...ANTICYCLONIC S TO SW WINDS WERE FLOWING INTO THE S SIDE OF AN ELONGATED MONSOONAL TROUGH THAT DOMINATED S PORTIONS OF THE AREA...WITH AN EASTERN SEGMENT EXTENDING FROM THE SW CARIBBEAN ACROSS NICARAGUA AND HONDURAS TO OFFSHORE OF THE MEXICAN COAST NEAR 15N96W. A LARGER AND MORE CONVECTIVELY ACTIVE SEGMENT OF THIS TROUGH EXTENDED FROM NEAR 17N103W TO 12N120W TO 12N125W TO 09N140W AND BEYOND. SCATTERED TO LOCALLY NUMEROUS CONVECTION WAS OCCURRING S OF THIS TROUGH AXIS IN THE CONFLUENT SW WIND FLOW...N OF 05N BETWEEN 84W AND 93W...AND WITHIN 270 NM OF THE MEXICAN COAST BETWEEN 93W AND 106W. SCATTERED MODERATE CONVECTION WAS ALSO NOTED WITHIN 90 NM EITHER SIDE OF THE TROUGH BETWEEN 120W AND 127W...AND W OF 137W. ...DISCUSSION... A DEEP LAYERED CYCLONE CONTINUED ACROSS THE NE PACIFIC WITH A SHEARED MID TO UPPER TROUGH AXIS EXTENDING FROM THE LOW TO 30N140W TO JUST NE OF THE HAWAIIAN ISLANDS. A RATHER EXTENSIVE ANTICYCLONE AND RIDGE DOMINATED MOST OF THE EAST PACIFIC AND MEXICO WITH THE AXIS EXTENDING SW FROM AN UPPER HIGH NEAR 24N112W TO 12N148W. ANTICYCLONIC CONFLUENT MID TO UPPER LEVEL FLOW ACROSS THE NW QUADRANT OF THE RIDGE WAS YIELDING DRY AND STABLE CONDITIONS N OF 20N EXTENDING NW TO THE TROUGH. THIS RIDGE WAS THE W PART OF A LARGE RIDGE COVERING THE GULF OF MEXICO AND NW CARIB...WITH TWO HIGH CENTERS SEPARATED BY A MID TO UPPER TROUGH MEANDERING FROM EXTREME W TEXAS S INTO CENTRAL MEXICO. S OF THE BROAD RIDGE AXIS...NE TO E UPPER LEVEL FLOW DOMINATED MOST OF THE DISCUSSION AREA S OF 19N...FRO CENTRAL AMERICA TO NEAR 140W. DEEP CONVECTION ASSOCIATED WITH THE MONSOON TROUGH AND EMBEDDED LOWS CONTINUED ALONG THE W COAST OF MEXICO S OF 19N AND ALSO BETWEEN 115W AND 130W...WHERE THE UPPER LEVEL FLOW WAS DIVERGING AROUND THESE DEEP CONVECTIVE CELLS. A MID TO UPPER LEVEL TROUGH EXTENDING FROM THE SW CARIB SE ACROSS COSTA RICA WAS AIDING IN CREATING INSTABILITY ACROSS THE FAR NE PORTION OF THE AREA...AND THE E END OF THE MONSOON TROUGHING...LEADING TO SCATTERED MODERATE TO STRONG CONVECTION N OF 05N AND E OF 92W...AND IMPROVED ORGANIZATION IN THE LOW LEVEL CYCLONIC FLOW THERE. LATEST SATELLITE IMAGERY AND LOW LEVEL STREAMLINE ANALYSIS CONTINUE TO DEPICT A WELL DEVELOPED MONSOONAL CIRCULATION ACROSS THE AREA...WITH SEPARATE SEGMENTS OF A TROUGH AXIS AS DESCRIBED ABOVE UNDER THE ITCZ SECTION. A FEW EMBEDDED MONSOONAL LOWS WERE FOUND WITHIN THE TROUGH...NEAR 15N113W AND 12N125W. THIS EASTERN MOST LOW WAS BENIGN AND A LOW LEVEL CLOUD SWIRL WHILE THE WESTERN MOST LOW WAS ACCOMPANIED BY SCATTERED MODERATE CONVECTION IN THE SW QUADRANT. SW WINDS OF 20-25 KT WERE NOTED S OF THE TROUGH MOST NOTABLY FROM 5N TO 15N BETWEEN 105W AND 128W. LATEST GLOBAL MODEL RUNS SUGGEST A NEW LOW DEVELOPING WITHIN THE TROUGH AXIS OFF OF THE MEXICAN COAST NEAR 19N108W DURING THE NEXT 48 HOURS. ABUNDANT MOISTURE EXISTS WITHIN THIS PORTION OF THE TROUGH...AND SOME ADDITIONAL MOISTURE FROM THE REMNANTS OF KARL COULD BECOME A PLAYER IN THE EVOLUTION OF THIS LOW. THERE IS SOME POTENTIAL FOR GRADUAL ORGANIZATION OF A LOW FROM THIS END OF THE TROUGH IN THE NEXT SEVERAL DAYS. AN EARLY SEASON COLD FRONT WAS JUST ENTERING THE FAR NW CORNER OF THE AREA...SUPPORTED BY THE SHEARED UPPER TROUGH. THIS FRONT WILL MAKE LITTLE PROGRESS SE OVER THE NEXT FEW DAYS BEFORE DISSIPATING. WINDS TO 20 KT AND SEAS TO 8 FT WILL BE SEEN WITHIN 150 NM SE OF THE FRONT THROUGH TONIGHT. MARINE... LONG PERIOD SW SWELL OF 14 TO 17 SECONDS WILL ADD TO LOCALLY DEVELOPED SEAS IN THE AREA OF THE 20 KT SW WINDS S OF MONSOON TROUGH TO POSSIBLY PRODUCE SEAS UP TO 12 OR 13 FT THROUGH THE NEXT 48 HOURS. OTHERWISE...SEAS WILL BE DOMINATED BY FADING SRN HEMI SW SWELL...AND WIND WAVES ASSOCIATED WITH THE BROAD SWLY FLOW S OF THE TROUGH. $$ STRIPLING