000 AXPZ20 KNHC 221557 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC TUE SEP 22 2009 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1545 UTC. ...SPECIAL FEATURE... AN AREA OF LOW PRESSURE 1008 MB IS NEAR 15N115W...ABOUT 550 NM SW OF THE SOUTHERN TIP OF BAJA CALIFORNIA. A 1350 UTC QUIKSCAT PASS SHOWED AN AREA OF 20 KT WINDS JUST N OF THE LOW IN RAIN-FREE AREAS. THIS PASS ALSO INDICATED THAT THE CIRCULATION WAS STILL ELONGATED ALONG A SW-NE AXIS. FIRST VISIBLE SATELLITE IMAGES OF THE DAY INDICATED THAT CONVECTION WAS BECOMING INCREASINGLY ORGANIZED AROUND THE LOW. SCATTERED MODERATE TO STRONG CONVECTION WAS NOTED WITHIN 180-240 NM IN THE NW SEMICIRCLE OF THE LOW. THE NUMERICAL MODELS AGREE ON FURTHER DEVELOPMENT OF THIS SYSTEM AS IT TRACKS NW WITH A REGION OF UPPER LEVEL DIFFLUENCE BETWEEN AN ANTICYCLONE OVER MEXICO NEAR 20N101W AND AN UPPER LOW NEAR 00N107W. THERE IS A HIGH CHANCE...GREATER THAN 50 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. ...THE ITCZ... THE INTERTROPICAL CONVERGENCE ZONE IS ALONG 07N78W TO 07N92W TO 15N110W TO 09N133W TO 11N140W. SCATTERED MODERATE TO STRONG WITHIN 180 NM N AND 90 NM S OF AXIS E OF 83W. SCATTERED MODERATE WITHIN 90 NM S OF AXIS BETWEEN 115W AND 118W. ...DISCUSSION... N OF 20N... THE REMNANTS OF MARTY ARE DEPICTED AS A TROUGH ALONG 131W FROM 18N TO 26N. WINDS AND SEAS ARE EXPECTED TO DIMINISH FURTHER WITH THIS SYSTEM LATER TODAY. A SMALL CIRCULATION LOW PRES AREA NEAR 22N115W...ABOUT 290 NM W OF THE SOUTHERN TIP OF BAJA CALIFORNIA IS NEARLY STATIONARY. THE 1350 UTC QUIKSCAT PASS SUGGESTED THIS SYSTEM MAY HAVE OPENED UP INTO A TROUGH AS WELL. AS SUCH THIS SYSTEM WILL BE DEPICTED AS A TROUGH ON THE 1800 UTC SURFACE ANALYSIS. WEAK HIGH PRES AND MOSTLY BROKEN STRATOCUMULUS WILL PERSIST ELSEWHERE OVER N WATERS THROUGH THE PERIOD WITH SOME CIRRUS NOTED ALONG THE EDGE OF A 60 KT WESTERLY JET CUTTING THROUGH 22N140W 23N125W INTO THE SOUTHERN EDGE OF THE POSITIVELY TILTED UPPER TROUGH OVER THE SOUTHWEST U.S. AND NW MEXICO. THE UPPER TROUGH AND JET AXIS ARE EXPECTED TO REMAIN STATIONARY THE NEXT FEW DAYS. THE COLD FRONT ASSOCIATED WITH THIS TROUGH WILL PASS SOUTH INTO NORTHERN MEXICO LATER TODAY. MODELS SHOW INCREASING AGREEMENT ON WINDS INCREASING TO 20 KT OVER THE NORTHERN GULF OF CALIFORNIA ON WED. FOR NOW HOWEVER HELD OFF ON ANY MENTION OF WINDS ABOVE 20 KT IN THE HIGH SEAS FORECAST. S OF 20N... AN UPPER LEVEL RIDGE AXIS SPAWNING FROM A SMALL ANTICYCLONE CENTERED NEAR THE GULF OF FONSECA AND EXTENDING SE INTO THE GULF OF PANAMA IS GENERATING DIFFLUENCE ALOFT. THE RESULTING VERTICAL LIFT OF THE LOW LEVEL MOISTURE POOLED ALONG THE ITCZ OVER THE FAR EASTERN WATERS IS THE IMPETUS FOR THE LARGE AREA OF SCATTERED MODERATE TO STRONG CONVECTION FOUND WITHIN 180 NM N AND 90 NM S OF THE ITCZ AXIS E OF 83W. THE SMALL ANTICYCLONE IS EXPECTED TO MERGE WITH THE LARGER ANTICYCLONE OVER MEXICO LATER TODAY. WHILE CONDITIONS SHOULD STILL REMAIN BROADLY DIFFLUENT OVER THIS AREA ALOFT. THE GFS HAS BACKED OFF ON THE FORECAST OF A 1005 MB LOW PRES SYSTEM OFF THE SOUTHERN TIP OF PANAMA. THE SYSTEM THAT IS FORECAST IS WEAKER WITH SOUTHWESTERLY WINDS OF 20 KT AND SEAS TO 8 FT OVER THE AREA LATER TODAY. THIS MAY BE AN OVERESTIMATE BUT IS NOW IN LINE WITH OTHER MODELS. ELSEWHERE ASIDE FROM THE PREVIOUSLY MENTIONED SYSTEMS...A WEAK SURFACE TROUGH FOUND ALONG 130W FROM 07N TO 14N IS CAUSING A WEAK PERTURBATION IN THE ITCZ. CONVECTION HAS INCREASED OVER THE LAST 24 HOUR NEAR THE TROUGH...WITH SCATTERED MODERATE TO STRONG CONVECTION CURRENTLY WITHIN 120 NM EITHER SIDE OF THE TROUGH FROM 06N TO 11N. GAP WINDS... THE COLD FRONT PASSING SOUTH INTO MEXICO TODAY IS EXPECTED TO BRING NORTHERLY FLOW THROUGH THE BAY OF CAMPECHE INTO THE GULF OF TEHUANTEPEC IN APPROXIMATELY 48 HOURS. WINDS ARE EXPECTED TO INCREASE TO 20 KT BY EARLY THU MORNING. $$ COBB