000 AXPZ20 KNHC 161605 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC WED SEP 16 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 1515 UTC. ...SPECIAL FEATURE... NEWLY UPGRADED TROPICAL STORM MARTY...THE THIRTEENTH OF THE 2009 EASTERN NORTH PACIFIC HURRICANE SEASON...WAS LOCATED NEAR 18.9N 112.4W AT 15Z THIS MORNING...BASED ON THE FIRST VISIBLE SATELLITE IMAGES AND A 13Z QUIKSCAT PASS. MAXIMUM SUSTAINED WINDS WERE 35 KT WITH GUSTS TO 40 KT. MINIMUM CENTRAL PRESSURE WAS ESTIMATED AT 1003 MB. THE CIRCULATION OF MARTY HAS FINALLY BEGUN TO SEPARATE FROM THE NE END OF THE ELONGATED MONSOON LIKE CIRCULATION THAT HAS EVOLVED OVER THE PAST SEVERAL DAYS ACROSS THE TROPICAL EASTERN PACIFIC. UPPER LEVEL ANTICYCLONIC FLOW HAD BECOME WELL ESTABLISHED OVER MARTY OVERNIGHT...ALLOWING A SMALL BUT CLASSIC CDO CONVECTIVE PATTERN TO DEVELOP OVER THE SYSTEM... BUT THE HIGH HAS SINCE SHIFTED SLIGHTLY EASTWARD AND IS PRODUCING WEAK AND SLIGHT SLY WIND SHEAR ACROSS THE W PORTIONS OF MARTY. THIS IS...HOWEVER...NOT INHIBITIVE FOR MODEST INTENSIFICATION OF MARTY DURING THE NEXT 24 HOURS. MARTY WAS ESTIMATED TO BE DRIFTING SLOWLY TOWARD THE NW DURING THE PAST 6 HOURS...AND WILL LIKELY REMAIN VERY SLOW TOWARD TO N OR N-NW DURING THE NEXT 24 HOURS BEFORE INCREASING ITS FORWARD MOTION. MARTY IS SANDWICHED BETWEEN TWO DEEP LAYERED HIGH...ONE TO THE E AND ANOTHER WELL TO THE W-NW...PREVENTING ANY SIGNIFICANT MOVEMENT OF THE SYSTEM. A MID TO UPPER LEVEL LOW AND TROUGH ALONG 120W AND OFFSHORE OF BAJA CALIFORNIA IS SINKING SLOWLY SOUTHWARD...AND HAS BEN AIDING IN PRODUCING FAVORABLE ANTICYCLONIC OUTFLOW FOR MARTY. HOWEVER...AS THIS LOW SINKS FURTHER S AFTER 24 HOURS...SWLY SHEAR IS EXPECTED TO COMBINE WITH COOLING SEA SURFACE TEMPS AND BEGIN A WEAKENING PROCESS FOR MARTY. ...TROPICAL WAVE... A TROPICAL WAVE WAS ANALYZED ALONG 125W MOVING W 10 TO 15 KT. THIS SMALL PERTURBATION HAS RECENTLY CAUGHT UP TO A WWD DRIFTING CONVERGENCE ZONE INDICATED IN SATELLITE AND TPW ANIMATIONS... ASSOCIATED WITH A LOW TO MID LEVEL LOW AND S EXTENDING TROUGH. THERE WAS ONLY ISOLATED CONVECTION WITHIN THE ITCZ ASSOCIATED WITH THIS WAVE. ...THE ITCZ... THE INTERTROPICAL CONVERGENCE ZONE WAS ALONG THE LINE FROM 08N78W TO 08N105W TO 11N121W TO 08N131W TO 09N140W. SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION WAS WITHIN 150 NM EITHER SIDE OF THE ITCZ AXIS E OF 103W. ISOLATED TO SCATTERED MODERATE TO STRONG CONVECTION WAS WITHIN 150 NM S OF AXIS FROM 122W TO 136W...AND MORE NUMEROUS W OF 136. ...DISCUSSION... N OF 20N...A SURFACE RIDGE...ANCHORED ON A 1020 MB HIGH PRES NEAR 30N128W CONTINUES TO BUILD SOUTHWARD OVER THE N WATERS. THE REGION IS MARKED BY MODERATE TO STRONG SUBSIDENCE WITH BROKEN STRATOCUMULUS CLOUDS COVERING THE AREA E OF 130W. THE PRES GRADIENT BETWEEN THIS RIDGE AND A SFC TROUGH OVER BAJA CALIFORNIA WAS PRODUCING NW WINDS NEAR 20 KT AND SEAS NEAR 8 FT N OF 27N WITHIN 120 NM OF THE BAJA PENINSULA. SATELLITE IMAGERY IS STILL SHOWING A SWIRL OF LOW CLOUDS NEAR 23N143W ASSOCIATED WITH THE REMNANTS OF LINDA WHICH HAVE BEEN DEGRADED TO A SURFACE TROUGH ALONG 143W. THE LEADING EDGE OF A COLD FRONT IS APPROACHING THE FAR NW CORNER OF THE AREA. A DEEP-LAYER TROUGH SUPPORTS THIS FRONTAL SYSTEM. THE FRONT WILL MOVE INTO NW WATERS OVERNIGHT AND IS EXPECTED TO DISSIPATE BY THU MORNING. SIGNIFICANT WAVE HEIGHTS WILL BUILD INTO THE 8 TO 10 FT RANGE IN W-NW SWELL WED AND THU OVER THESE NW WATERS. S OF 20N...ASIDE FROM TROPICAL STORM MARTY...THE TROPICAL WAVE...AND THE CONVECTION ALONG THE ITCZ...CONDITIONS ARE RELATIVELY QUIET OVER THE REMAINDER OF THE AREA. A DIFFLUENT PATTERN ALOFT ASSOCIATED WITH AN UPPER-LEVEL ANTICYCLONE CENTERED OVER THE YUCATAN CHANNEL IS HELPING TO INDUCE CONVECTION OVER THE FAR EPAC WATERS AND ALONG THE ITCZ PARTICULARLY E OF 100W. WAVE HEIGHTS BETWEEN 105W AND 130W WERE GENERALLY RUNNING AT 8 TO 9 FT IN A MIX OF LONG PERIOD NW SWELL AND SRN HEMI SE WIND SWELL. FRESH S TO SW FLOW ASSOCIATED WITH THE S AMERICAN MONSOON CIRCULATION WERE PRODUCING SEAS NEAR 8 FT BETWEEN THE GALAPAGOS ISLANDS AND PANAMA. OTHERWISE...SEAS WERE GENERALLY LESS THAN 8 FT ACROSS THE AREA. $$ SS