000 AXPZ20 KNHC 222137 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC TUE SEP 22 2009 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2115 UTC. ...SPECIAL FEATURE... AN AREA OF LOW PRESSURE 1008 MB IS NEAR 15N115W...ABOUT 540 NM SW OF THE SOUTHERN TIP OF BAJA CALIFORNIA. THIS LOW HAS ESSENTIALLY BEEN DRIFTING SLOWLY W THROUGHOUT THE DAY. A HIGH RESOLUTION 1350 UTC QUIKSCAT PASS SHOWED AN AREA OF 20 TO 25 KT WINDS WITHIN 180 NM IN THE N SEMICIRCLE OF THE LOW IN RAIN-FREE AREAS. AS NOTED EARLIER...THIS PASS SUGGESTED THAT THE CIRCULATION WAS STILL ELONGATED ALONG A SSW-NNE AXIS. VISIBLE SATELLITE IMAGERY THROUGHOUT THE DAY INDICATED THAT CONVECTION WAS BECOMING INCREASINGLY ORGANIZED AROUND THE LOW WITH SOME BANDING FEATURES NOTED. SCATTERED MODERATE TO STRONG CONVECTION WAS NOTED WITHIN 180-240 NM MAINLY 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 07N90W TO 09N100W TO 11N113W TO 08N127W TO 10N140W. SCATTERED MODERATE TO STRONG WITHIN 180 NM S OF AXIS BETWEEN 81W AND 89W AND 60 NM S OF AXIS BETWEEN 91W AND 93W. SCATTERED MODERATE ISOLATED STRONG WITHIN 180 NM S OF AXIS BETWEEN 118W AND 122W AND 130W AND 133W. SCATTERED MODERATE WITHIN 120 NM S OF AXIS BETWEEN 115W AND 118W AND 122W AND 130W. ...DISCUSSION... N OF 20N... THE REMNANTS OF MARTY ARE DEPICTED AS A TROUGH ALONG 131W/132W FROM 18N TO 26N. WINDS AND SEAS HAVE DIMINISHED WITH THIS SYSTEM TODAY. THE LOW PRES AREA NOTED EARLIER NEAR 22N115W HAS DISSIPATED. THIS WAS CONFIRMED BY A 1350 UTC HIGH RESOLUTION QUIKSCAT PASS. 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 EXTENDING FROM A SMALL ANTICYCLONE CENTERED NEAR THE GULF OF FONSECA 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 S OF THE ITCZ AXIS BETWEEN 81W AND 89W. THE SMALL ANTICYCLONE APPEARS TO BE MERGING WITH THE LARGER ANTICYCLONE OVER MEXICO. 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