000 AXPZ20 KNHC 140350 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC FRI OCT 14 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... AT 14/0300 UTC...TROPICAL STORM IRWIN IS CENTERED NEAR 19.2N 106.6W AND REMAINS NEARLY STATIONARY. LITTLE MOTION IS EXPECTED DURING THE NEXT 12 TO 24 HOURS...AND A SLOW SOUTHWARD MOTION SHOULD BEGIN THEREAFTER. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1003 MB. THE MAXIMUM SUSTAINED WIND SPEEDS HAVE SLIGHTLY INCREASED TO 40 KT WITH GUSTS TO 50 KT. THREE DIFFERENT SHIPS WITH CALL SIGN...DNCQ...DGDD...AND V2AC6 LOCATED NEAR AND TO THE EAST OF IRWIN REPORTED AT THE SAME TIME WINDS OF TROPICAL STORM FORCE. LITTLE CHANGE IN STRENGTH IS FORECAST DURING THE NEXT 48 HOURS. NUMEROUS MODERATE CONVECTION IS NOTED WITHIN 75 NM NE SEMICIRCLE OF IRWIN. SCATTERED MODERATE CONVECTION CAN BE FOUND ELSEWHERE FROM 18N TO 20N BETWEEN 105W AND 109W. PLEASE READ THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP1/WTPZ21 KNHC AND/OR THE PUBLIC ADVISORY UNDER MIATCPEP1/WTPZ31 KNHC FOR MORE DETAILS. ...ITCZ/MONSOON TROUGH... MONSOON TROUGH OVER PARTS OF NORTHERN CENTRAL AMERICA AND SE MEXICO THEN RESUMES W OF T.S. IRWIN FROM 12N110W TO LOW PRES NEAR 10N127W TO 08N140W. NO DEEP CONVECTION IN ASSOCIATION WITH THE MONSOON TROUGH W OF 110W. SOUTH OF THE MONSOON TROUGH SCATTERED TO NUMEROUS MODERATE TO ISOLATED STRONG CONVECTION IS NOTED FROM 12N TO 15N BETWEEN 91W AND 99W. SCATTERED MODERATE CONVECTION IS FROM 04N TO 06N BETWEEN 80W AND 83W...AND FROM 12N TO 14N BETWEEN 102W AND 108W. ...DISCUSSION... A COLD FRONT IS CURRENTLY APPROACHING THE FAR NW CORNER OF THE FORECAST REGION...AND WILL REACH FROM 30N135W TO 24N140W BY FRI EVENING. NW WINDS OF 20 KT AND SEAS BUILDING UP TO 8-10 FT IN A NW SWELL ARE EXPECTED IN THE WAKE OF THE FRONT IN ABOUT 24 HOURS. BY 36 HRS...A RATHER SIGNIFICANT LOW PRES SYSTEM IS EXPECTED TO MOVE TO OVER THE FAR NW PART OF THE DISCUSSION AREA 31N138W. W-NW WINDS OF 20-30 KT ARE EXPECTED TO MATERIALIZE N OF 28N W OF 136W...WITH SEAS 9-15 FT IN NW SWELL. BY SAT EVENING...THE LOW WILL BE NEAR 31N136W WITH THE W-NW OF 20-30 KT FORECAST TO BE N OF 27N AND W OF 134W...WITH SEAS IN THE RANGE OF 12-20 FT IN NW SWELL. WATER VAPOR IMAGERY SHOWS AN UPPER LOW CENTERED NEAR 21N123W MOVING NWD. THE UPPER LOW IS TRANSPORTING TROPICAL MOISTURE NWD OVER THE AREA TO THE N OF 25N AND BETWEEN 115W-126W AS SEEN ON IR IMAGERY. THIS LOW WILL MOVE TOWARD THE N-NE TODAY BEFORE BEING PICKED UP BY THE DEEP LAYER TROUGH ASSOCIATED WITH THE COLD FRONT IN NW WATERS. A MID TO UPPER LEVEL RIDGE IS BUILDING ACROSS BAJA CALIFORNIA AND SOUTHERN CALIFORNIA. IRWIN WILL MOVE E-SE THEN S AROUND THE SOUTHERN PERIPHERY OF THIS RIDGE. UPPER-LEVEL NLY FLOW DOMINATES THE WATERS E OF 100W. FRESH TO STRONG WINDS ARE FLOWING INTO THE MONSOON TROUGH... WHICH EXTENDS OVER SOUTHERN MEXICO AND CENTRAL AMERICA INTO THE WESTERN CARIBBEAN. WITH THE MONSOON TROUGH EXPECTED TO REMAIN OVER THIS AREA...THESE WINDS WILL CONTINUE THROUGH THE FORECAST PERIOD...WITH SEAS REACHING UP TO 14 FT. FORECAST GUIDANCE SUGGESTS THAT A BROAD AREA OF LOW PRES WILL DEEPEN IN THE VICINITY OF THE YUCATAN PENINSULA OVER THE NEXT FEW DAYS AND FORCE STRONG N FLOW THROUGH THE GULF OF TEHUANTEPEC. WINDS ARE EXPECTED TO REMAIN BELOW GALE FORCE THERE. THE REMAINDER OF THE REGIONAL WATERS ARE DOMINATED BY MERGING NW AND SW SWELL. THIS SWELL WILL SLOWLY DECREASE FROM NW TO SW THROUGH THE NEXT 24 TO 48 HOURS...WHILE ANOTHER SET OF NW SWELLS IS EXPECTED TO ENTER THE AREA WITHIN THE NEXT 12-24 HOURS. $$ GR