000 AXPZ20 KNHC 081611 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC SAT OCT 08 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1500 UTC. ...SPECIAL FEATURES... HURRICANE IRWIN CENTERED NEAR 14.3N 121.0W AT 1500 UTC MOVING N-NW OR 345 DEG AT 3 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 986 MB. MAXIMUM SUSTAINED WIND SPEED IS 65 KT WITH GUSTS TO 80 KT. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP1/WTPZ21 KNHC FOR MORE DETAILS. OUTFLOW FROM THE WIDESPREAD CONVECTION ASSOCIATED WITH TROPICAL STORM JOVA HAS PRODUCE MODERATE ELY WIND SHEAR THAT HAS IMPINGED UPON IRWIN...LEAVING A PARTIALLY EXPOSED LLVL CIRCULATION CENTER THIS MORNING...WITH CONVECTION DISPLACED TO THE W-SW. IRWIN IS EXPECTED TO MOVE LITTLE OVER THE NEXT 24 HOURS...BUT THEREAFTER IS FORECAST TO MOVE E-NE IN THE GENERAL DIRECTION OF W CENTRAL MEXICO THROUGH 120 HOURS. IRWIN IS FORECAST TO MAINTAIN ITS CURRENT INTENSITY THROUGH 24 HOURS THEN STRENGTHEN SLIGHTLY THROUGH WED. SCATTERED TO NUMEROUS MODERATE TO STRONG CONVECTION WAS OCCURRING FROM 45 TO 240 NM ACROSS THE W SEMICIRCLE OF IRWIN. TROPICAL STORM JOVA CENTERED NEAR 15.8N 110.4W AT 1500 UTC MOVING NE OR 45 DEG AT 3 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 993 MB. MAXIMUM SUSTAINED WIND SPEED IS 60 KT WITH GUSTS TO 75 KT. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP5/WTPZ25 KNHC FOR MORE DETAILS. JOVA IS EXPECTED TO BEGIN MOVING E-NE TOWARD W CENTRAL MEXICO TODAY WITH THE CURRENT FORECAST INDICATING JOVA WILL INLAND ON TUE. ADDITIONAL STRENGTHENING IS FORECAST UNTIL LANDFALL...WITH JOVA FORECAST TO REACH HURRICANE STRENGTH BY THIS EVENING. NUMEROUS MODERATE TO STRONG CONVECTION LIES WITHIN 90 NM NE AND 120 NM SW SEMICIRCLES OF JOVA WITH SCATTERED MODERATE CONVECTION ELSEWHERE WITHIN 360 NM ACROSS THE W SEMICIRCLE. A 1008 MB LOW PRES CENTERED NEAR 11N97W HAS BEEN DRIFTING WEST AROUND 5 KT OVER THE LAST 12 HOURS...BUT THE LOW IS EXPECTED TO SLOW TODAY AND BEGIN MOVING EASTWARD TONIGHT THROUGH MON. SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 150 NM OF THE LOW PRES CENTER. ATMOSPHERIC CONDITIONS APPEAR CONDUCIVE FOR ADDITIONAL DEVELOPMENT OF THIS SYSTEM...AND THERE IS A GOOD CHANCE IT MAY BECOME A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. ...ITCZ/MONSOON TROUGH... MONSOON TROUGH AXIS FROM 10N85W TO 12N91W TO LOW PRES NEAR 11N97W 1008 MB TO 12N100W WHERE THERE IS A BREAK IN THE TROUGH DUE TO THE CIRCULATION AROUND HURRICANE IRWIN AND TROPICAL STORM JOVA. THE MONSOON TROUGH THEN RESUMES FROM 12N125W TO 08N132W TO 08N135W. ITCZ AXIS EXTENDS FROM 08N135W TO 08N140W. SCATTERED MODERATE CONVECTION WITHIN 150 NM S SIDE OF AXIS BETWEEN 87N AND 89W. SCATTERED MODERATE CONVECTION 60 NM EITHER SIDE OF AXIS BETWEEN 95W AND 100W. ...DISCUSSION... 1027 MB HIGH PRES IS CENTERED N OF THE AREA NEAR 35N135W WITH A RIDGE AXIS EXTENDING SE TO NEAR 21N112W. THE PRES GRADIENT BETWEEN THIS RIDGE AND LOWER PRES ASSOCIATED WITH HURRICANE IRWIN AND TROPICAL STORM JOVA CONTINUES TO PRODUCE FRESH NE TRADES FROM 17N TO 22N W OF 117W...WHICH HAS SHRUNKEN SLIGHTLY SOUTHWARD DURING THE PAST 8 HOURS. THESE TRADES ARE NOT EXPECTED TO CHANGE MUCH FURTHER THROUGHOUT THE REMAINDER OF THE DAY...BUT WILL SHRINK TONIGHT THROUGH SUNDAY ACROSS W PORTIONS AS THE SUBTROPICAL HIGH REORGANIZES FURTHER TO THE SW DUE TO A PROGRESSIVE COLD FRONT IMPINGES UPON IT FROM THE N. IN ADDITION...THE PRES GRADIENT BETWEEN THE RIDGE AND TROUGHING OVER INLAND MEXICO IS MAINTAINING FRESH NW TO N WINDS OVER THE GULF OF CALIFORNIA N OF 25N WHICH WILL PERSIST THROUGH THE NEXT 48 HOURS AS WELL AS WITHIN 120 NM OF THE W COAST OF BAJA CALIFORNIA. WINDS W OF THE BAJA PENINSULA ARE EXPECTED TO DIMINISH LATE TONIGHT AND SUNDAY AS THE SUBTROPICAL HIGH BEGINS TO SHIFT WESTWARD AND THE PRES GRADIENT RELAXES. WATER VAPOR IMAGERY THIS MORNING SHOWS A STRONG UPPER LEVEL TROUGH MOVING QUICKLY E-SE ACROSS THE NE PACIFIC NEAR 140W...AND IS EXPECTED TO REACH THE W COAST OF N AMERICA BY SUNDAY MORNING...AND EXTEND SW TO NEAR 21N140W. AS THIS TROUGH CONTINUES EWD SUN AND MON ACROSS THE WRN U.S. AND NRN MEXICO...IT WILL ACT TO NUDGE THE TWO TROPICAL CYCLONES ON AN ENE TO NE TRAJECTORY AS INDICATED BY THE GLOBAL MODELS...AND REFLECTED IN THE FORECASTS FOR IRWIN AND JOVA. MONSOONAL FLOW DOMINATES THE REMAINDER OF THE AREA WITH THE THREE TROPICAL SYSTEMS NOTED ABOVE ORIGINATING WITHIN THE MONSOON TROUGH. IRWIN AND JOVA REMAIN EMBEDDED WITHIN THE WESTERN END OF THIS MONSOONAL CIRCULATION...WHILE THE LOW CENTER NEAR 11N97W IS EMBEDDED WITHIN THE W PORTION OF A MONSOONAL GYRE WHICH IS ANCHORED BY A BROAD AND WEAK LLVL CYCLONIC CIRCULATION ACROSS THE EXTREME SW CARIBBEAN. SW TO W FLOW OF 20 TO LOCALLY 25 KT IS EXPECTED TODAY FROM THE MONSOON TROUGH S TO ABOUT 05N FROM ABOUT 98W EWD TO PANAMA AND COLOMBIA....WHICH WILL MAINTAIN LLVL CONFLUENCE AND CONTINUE TO PRODUCE ACTIVE CONVECTION ACROSS THIS ZONE. THIS ENHANCED SWLY FLOW IS EXPECTED TO CREATE FAVORABLE CONDITIONS FOR INCREASED CONVECTION AND ORGANIZATION OF THE LOW AT 11N97W. NW SWELL IS CONTINUING TO PROPAGATE THROUGH THE NORTHERN FORECAST WATERS AND IS MERGING WITH THE 15-17 PERIOD CROSS-EQUATORIAL SW SWELL OVER CENTRAL WATERS INCLUDING THE AREA NEAR JOVA AND IRWIN...WHERE COMBINED SEAS ARE AS HIGH AS 12 FT. THIS MERGING SWELL COMBINED WITH SWLY WIND WAVES DEVELOPING WITHIN THE MONSOONAL SW FLOW IS CREATING A VERY CONFUSED SEA STATE ACROSS CENTRAL WATERS THAT IS EXPECTED TO PERSIST THROUGH THE WEEKEND. A NEW PULSE OF NW SWELL WILL PROPAGATE INTO THE FORECAST AREA BY EARLY SUN...WITH SEAS EXPECTED TO BUILD TO 8 FT OVER N CENTRAL FORECAST WATERS. $$ STRIPLING/JS