000 AXPZ20 KNHC 160256 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC SUN OCT 16 2011 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0215 UTC. ...SPECIAL FEATURES... IRWIN IS DOWNGRADED TO A TROPICAL DEPRESSION AT 16/0300 UTC. AT THIS TIME...IT IS CENTERED NEAR 14.8N 107.3W MOVING S-SW OR 200 DEGREES AT 8 KT. A TURN TOWARD THE SOUTHWEST AND WEST-SOUTHWEST WITH A DECREASE IN FORWARD SPEED IS EXPECTED ON SUNDAY. IRWIN COULD THEN BECOME NEARLY STATIONARY ON MONDAY. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006 MB. MAXIMUM SUSTAINED WIND SPEED HAS DECREASED TO 30 KT WITH GUSTS TO 40 KT. LITTLE CHANGE IN STRENGTH IS FORECAST THROUGH MONDAY...BUT IRWIN COULD DEGENERATE INTO A REMNANT LOW AT ANY TIME IF IT CEASES TO PRODUCE ORGANIZED SHOWERS AND THUNDERSTORMS. SCATTERED MODERATE CONVECTION IS ONLY NOTED WITHIN 90 NM SW QUADRANT. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP1/WTPZ21 KNHC FOR MORE DETAILS. ...ITCZ/MONSOON TROUGH... MONSOON TROUGH EXTENDS FROM 13N89W TO 12N94W TO 16N97W THEN ACROSS SW MEXICO TO NEAR 17N105W THEN RESUMES SW OF IRWIN FROM 14N108W TO 10N125WW TO 11N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS N OF 12N BETWEEN 90W AND 94W...AND WITHIN 30 NM OF 13N95W. SCATTERED MODERATE CONVECTION IS ALSO WITHIN 30 NM OF 12N119W. ...DISCUSSION... A 1006 MB LOW PRES IS SPINNING JUST N OF THE AREA NEAR 31N138W. A COLD FRONT EXTENDS FROM THE LOW TO 30N131W TO 21N140W. LATEST SCATTEROMETER DATA AS WELL AS A SHIP OBSERVATIONS INDICATE FRESH TO STRONG W TO NW WINDS IN THE WAKE OF THE FRONT. SEAS ARE ALSO RUNNING UP TO 14 FT IN NW SWELL OVER THE NW PART OF THE AREA BEHIND THE FRONTAL SYSTEM. THE LOW PRESSURE AREA WILL SLOWLY SHIFT E OVER THE NEXT 48 HOURS...AND REMAIN ALONG OR JUST N OF 30N. THE FRONT WILL SHIFT SLOWLY E THEN DISSIPATE WITHIN 48 HOURS WITH ASSOCIATED WINDS DIMINISHING BELOW 20 KT. THE NW SWELL WILL CONTINUE TO PROPAGATE S AND SE THROUGH THE FORECAST PERIOD WITH COMBINED SEAS GRADUALLY SUBSIDING TO NEAR 9 FT. AN EXTENSIVE AREA OF FRESH TO STRONG SW MONSOONAL FLOW PREVAILS N OF 06N E OF 100W. THIS MONSOONAL FLOW CONTINUES TO ADVECT ABUNDANT MOISTURE NORTHWARD INTO PARTS OF CENTRAL AMERICA AND S MEXICO WHICH WILL BRING PERIODS OF VERY HEAVY RAINFALL OVER PORTIONS OF THE PACIFIC COASTS OF SOUTHEASTERN MEXICO... GUATEMALA...EL SALVADOR...SOUTHERN HONDURAS AND NICARAGUA. THESE PERIODS OF HEAVY MONSOONAL RAINFALL HAS THE POTENTIAL TO CREATE LIFE-THREATENING FLASH FLOODS AND MUD SLIDES OVER THESE AREAS. AN EARLIER HIGH RESOLUTION ASCAT PASS INDICATED 20-30 KT NORTHERLY WINDS IN AND DOWNSTREAM OF THE GULF OF TEHUANTEPEC AROUND A BROAD CYCLONIC CIRCULATION CURRENTLY CENTERED OVER THE YUCATAN PENINSULA NEAR 19N88W. DUE TO THE INFLUENCE OF THIS CYCLONIC CIRCULATION OVER THE AREA...THE WINDS FUNNELING INTO THE GULF OF TEHUANTEPEC ARE TURNING NW THEN WEST AS IT MOVES FURTHER FROM THE GULF OF TEHUANTEPEC. TYPICALLY...THE WINDS BLOWING THROUGH THE CHIVELA PASS INTO THE GULF OF TEHUANTEPEC TURN NE THEN E AS IT MOVES FURTHER FROM THIS GULF. THIS WEATHER PATTERN IS FORECAST TO PERSIST OVER THE NEXT COUPLE OF DAYS AS THE BROAD LOW PRESSURE AREA MOVES W-NW PROBABLY TOWARD THE BAY OF CAMPECHE. THE REMAINDER OF THE REGIONAL WATERS E OF 130W ARE DOMINATED BY MERGING NW AND SW SWELL. THIS SWELL EVENT WILL GRADUALLY SUBSIDE FROM THE NW TO SE THROUGH THE NEXT 48 HOURS...WITH SEAS GREATER THAN 8 FT LIMITED TO S OF 12N AND E OF 125W BY MON. $$ GR/AL