000 AXPZ20 KNHC 300313 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC WED SEP 30 2009 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0300 UTC. ...SPECIAL FEATURES... UNDERNEATH AND TO THE S OF A LARGE UPPER LEVEL HIGH ALONG THE W COAST OF MEXICO HAS EVOLVED A LARGE AND BROAD LOW AND MID LEVEL CYCLONIC CIRCULATION...PORTIONS OF WHICH IN THE PREVIOUS DAYS MOVED ACROSS THE FAR W CARIBBEAN SEA...CENTRAL AMERICA...AND INTO THE S CENTRAL MEXICO AND THE ADJACENT PACIFIC WATERS COVERS THE AREA FROM ABOUT 15N TO 22N BETWEEN 108W AND 115W. A 1006 MB SURFACE LOW IS ANALYZED WITHIN THIS AREA TO BE NEAR 19N111W...WHICH IS NEAR WHERE A MID LEVEL CIRCULATION WAS EARLIER OBSERVED. IT IS MOVING WNW 10 KT. LAST VISIBLE IMAGERY SHOWED A WHAT APPEARS TO A CURVING BAND N OF THE LOW CENTER. IR IMAGERY IS SHOWING SCATTERED MODERATE/ISOLATED STRONG CONVECTION WITHIN 180 NM OF THE CENTER IN THE NORTHERN SEMICIRCLE. THIS SYSTEM IS FORECAST BY GLOBAL MODELS TO SHIFT NW OVER THE NEXT FEW DAYS AS IT SLOWLY BECOMES BETTER ORGANIZED...POSSIBLY INTO A TROPICAL CYCLONE IN 48 HOURS. ...TROPICAL WAVE... A TROPICAL WAVE IS ALONG 98W FROM 6N-14N MOVING W 15 KT. SCATTERED MODERATE CONVECTION IS WITHIN 30 NM OF THE WAVE. ...ITCZ... AXIS WAS CENTERED ALONG 8N79W TO 8N90W TO 12N100W TO 16N110W TO 13N121W TO 15N131W TO 12N140W. SCATTERED STRONG CONVECTION IS WITHIN 45 NM OF THE AXIS BETWEEN 117W-122W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION EXISTS FROM 12N-17N BETWEEN 110W-117W...WITHIN 30 NM OF THE AXIS BETWEEN 122W-126W AND ALSO W OF 137W. SCATTERED MODERATE CONVECTION IS S OF THE AXIS WITHIN 30 NM OF A LINE FROM 6N101W TO 6N104W. ...DISCUSSION... A NARROWING DEEP LAYER TROUGH ENTERS THE REGION OVER THE NE PORTION OF THE AREA THROUGH 32N122W...AND EXTENDS SW TO AN ELONGATE CYCLONIC CIRCULATION NEAR 28N133W. A TROUGH CONTINUES SW FROM THIS CIRCULATION TO W OF THE AREA AT 24N140W. THE BASE OF THIS TROUGH IS VERY BROAD AND IS STILL CARVED OUT INTO THE NRN FRINGES OF THE TROPICS...EXTENDING FROM 16-20N BETWEEN 125W AND 152W. A 50-60 KT JET AXIS WAS MOVING THROUGH THE BACK SIDE OF THE BROAD TROUGH AND THROUGH THE BASE ALONG 18-21N...AND WAS EXITING AS A BROADER 60-90 KT JET ON THE E SIDE OF THIS AXIS LIFTING OUT AND INTO SRN CALIFORNIA AND THE WRN U.S. THIS UPPER TROUGH WILL MAINTAIN A SW-NE ELONGATION OVER THE NEXT FEW DAYS AS A BROAD OMEGA BLOCKING UPPER PATTERN SPANS N AMERICA. DOWNSTREAM...A WELL PRONOUNCED UPPER LEVEL ANTICYCLONE IS OVER WRN MEXICO NEAR 22N105W...AND IS SERVING AS A BLOCKING FEATURE ACROSS THIS PORTION OF THE AREA. A RIDGE EXTENDS SW FROM THE ANTICYCLONE TO 16N120W TO 12N129W...AND TO A COL REGION NEAR 12N137W AND THEN CONNECTED TO ANOTHER UPPER ANTICYCLONE LOCATED WELL W OF 140W. TO THE S OF THE ANTICYCLONE AND RIDGE...A DIFFLUENT PATTERN IS HELPING TO VENTILATE CONVECTION ALONG THE ITCZ GENERALLY BETWEEN 104W AND 121W. ELSEWHERE RATHER DRY AND SUBSIDENT CONDITIONS ARE NOTED ACROSS THE BASE OF THE UPPER TROUGH...AND ACROSS THE NW AND NRN FLANKS OF THE RIDGE...JUST SE OF THE SUBTROPICAL JET. AN AREA OF BROAD AND MODEST LOW TO MID LEVEL CYCLONIC TURNING IS NOTED SW OF THE GULF OF TEHUANTEPEC FROM 5N TO 14N BETWEEN 95W AND 105W...AND COVERS THE ENVIRONMENT ALOFT THE TROPICAL WAVE ALONG 98W. CONVECTION IS ENHANCED SOME WITHIN THIS AREA. AT THE SURFACE...A HIGH PRES RIDGE EXTENDS FROM A 1036 MB HIGH N OF THE AREA NEAR 42N148W SE TO OFFSHORE OF BAJA CALIFORNIA NEAR 24N114W. A 1008 MB LOW IS NEAR 14N121W MOVING W ABOUT 5-10 KT. A WEAK 1010 LOW IS NEAR 15N133W MOVING WSW 10 KT WITH ONLY ISOLATED SHOWERS AND TSTMS WITHIN 45 NM OF IT. GULF OF TEHUANTEPEC N-NE WINDS TO 20 KT ARE WITHIN 60 NM FROM THE COAST. THESE WINDS ARE FORECAST TO DIMINISH IN ABOUT 30 HOURS AS THE PRES GRADIENT OVER INTERIOR OF MEXICO WEAKENS. REGIONAL SEAS ARE BEING DOMINATED BY MODERATE PERIOD SRN HEMISPHERE SE SWELL...AND LONGER PERIOD NW AND SSW SWELL. THE FRESH TO STRONG E TO SE FLOW ALONG THE MEXICAN COAST WAS GENERATING SEAS OF 7 TO 10 FT IN THIS CONFUSED MIX. SEAS IN EXCESS OF 8 FT WILL GRADUALLY PROPAGATE NWD ACROSS THE EQUATOR TO 12N BY MID WEEK AS SEVERAL NEW PULSES OF LARGE SE AND SW SWELL MOVE INTO THE AREA. $$ AGUIRRE