000 AXPZ20 KNHC 270950 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC THU JUN 27 2013 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0945 UTC. ...SPECIAL FEATURES... TROPICAL STORM COSME AT 20.1N 119.3W 1002 MB AT 0900 UTC JUN 27 MOVING WNW OR 290 DEGREES AT 14 KT. MAXIMUM SUSTAINED WINDS ARE 40 KT WITH GUSTS TO 50 KT. SCATTERED MODERATE CONVECTION IS NOTED WITHIN 30 NM EITHER SIDE OF A LINE FROM 22N120W TO 20N121W...AND ALSO WITHIN 15 NM EITHER SIDE OF A LINE FROM 21N118W TO 19N118W TO 17N120W. COSME IS FORECAST TO WEAKEN TO A POST-TROPICAL REMNANT LOW PRESSURE TODAY AS IT MOVES OVER COOLER SEA SURFACE TEMPERATURES. SEE THE LATEST FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP3/WTNT23 KNHC FOR MORE DETAILS. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS W FROM COLOMBIA AT 09N76W TO ACROSS OVER NORTHERN PANAMA TO THE PACIFIC COAST OF THE PANAMA/ COSTA RICA BORDER TO 08N96W THROUGH AN EMBEDDED LOW PRESSURE DEVELOPING NEAR 10N101W TO 11N107W WHERE THE TROUGH LOSES IDENTITY IN BROAD CYCLONIC CIRCULATION ASSOCIATED WITH DISSIPATING TROPICAL CYCLONE COSME. THE MONSOON TROUGH RESUMES WELL SSW OF COSME NEAR 12N115W AND CONTINUES WSW TO BEYOND 07N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS FLARING ALONG THE EASTERN SEGMENT OF THE MONSOON TROUGH WITHIN 60 NM EITHER SIDE OF A LINE FROM 08N78W TO 08N97W...WITHIN THE AREA FROM 07N-14N BETWEEN 98W-113W...AND ALONG THE WESTERN SEGMENT OF THE MONSOON TROUGH WITHIN 30 NM EITHER SIDE OF A LINE FROM 12N115W TO 09N122W...AND WITHIN 30 NM OF 06N132W. SCATTERED MODERATE ISOLATED STRONG CONVECTION CONTINUES TO FLARE WITHIN 150 NM OF COAST OF MEXICO FROM 94W-104W. ...DISCUSSION... A CUT OFF UPPER CYCLONE AT 32N127W IS LIFTING N WHILE FILLING. AN UPPER ANTICYCLONE HAS FORMED NEAR 27N128W WITH AN UPPER RIDGE EXTENDING NW TO A SHARP CREST AT 31N138W WHERE IT IS BEGINNING TO BLOCK THE FORWARD ADVANCE OF AN APPROACHING SHORTWAVE TROUGH THAT IS IN TURN ACCOMPANIED BY FAIRLY DENSE UPPER MOISTURE. OTHERWISE THE UPPER LEVELS ARE VERY DRY W OF A LINE FROM THE NORTHERN BAJA CALIFORNIA PENINSULA TO 20N130W TO 10N130W. AN UPPER RIDGE ALSO EXTENDS SW FROM THE ANTICYCLONE TO A CREST AT 21N139W...AND WILL CONTRIBUTE TO THE STEERING OF THE RAPIDLY WEAKENING CYCLONE COSME EARLY TODAY. AT THE SURFACE A LOCALLY OVERCAST BAND OF LOW CLOUDS DEFINES THE SE EXTENT A DISSIPATING FRONTAL TROUGH FROM 31N131W TO 29N138W. NW SWELLS MAINTAIN SEAS OF 7-8 FT N OF 29N BETWEEN 133W-137W...BUT SHOULD SUBSIDE BELOW 8 FT IN A FEW HOURS. AN UPPER ANTICYCLONE IS CENTERED NEAR 20N112W WITH A RIDGE AMPLIFYING N TO A CREST AT 30N115W...AND A RIDGE ALSO EXTENDS SE TO A CREST AT 14N103W PROVIDING THE UPPER DIFFLUENCE OVER THE MONSOON TROUGH CONVECTION PREVIOUSLY DESCRIBED BETWEEN 110W- 118W. THIS CONVECTION CONTINUES TO CONTRIBUTE TO EXTREMELY DENSE UPPER MOISTURE OBSERVED S OF 12N BETWEEN 94W-118W. S OF THIS MOISTURE IS NOW ADVECTED NE ACROSS EXTREME SE MEXICO AND ACROSS GUATEMALA TO THE E OF AN UPPER TOUGH DIGGING S TO BASE OVER THE GULF OF TEHUANTEPEC. A 1018 MB SURFACE HIGH IS CENTERED AT 26N136W WITH A RIDGE EXTENDING E TO ACROSS THE CENTRAL BAJA CALIFORNIA PENINSULA. CROSS EQUATORIAL SOUTHERLY SWELL CONTINUES TO PROPAGATE N ACROSS THE DISCUSSION AREA BETWEEN 100W-130W...AND WAS REINFORCED BY SWELL GENERATED BY TROPICAL CYCLONE COSME. THESE SOUTHERLY SWELLS WILL PASS 30N TODAY THEN SUBSIDE BELOW 8 FT ACROSS THE DISCUSSION WATERS W OF 115W ON FRI. THE SOUTHERLY SWELLS... RESULTING IN COMBINED SEAS TO 10 FT...ACROSS THE GULF OF CALIFORNIA TO THE S OF 23N SHOULD SUBSIDE BELOW 8 FT THIS AFTERNOON. BROAD CYCLONIC TURNING IS NOTED ALONG THE MONSOON TROUGH NEAR 10N100W AND A SURFACE LOW IS EXPECTED TO FORM OVER THE NEXT DAY OR SO. MODEL GUIDANCE FAVORS TROPICAL DEVELOPMENT. THE OFFICIAL FORECAST ISSUED WITHIN THE MARINE GRIDS IS FOR A 1010 MB LOW NEAR 9.5N101W TONIGHT...MOVING W TO NEAR 10N104W ON FRI NIGHT...THEN MOVING NE AND INTENSIFYING THROUGH THE WEEKEND. $$ NELSON