000 AXPZ20 KNHC 030930 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC WED JUN 03 2009 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0915 UTC. ...ITCZ... AXIS FROM 06N78W TO 08N91W TO 12N105W TO 08N127W TO 06N140W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS WITHIN 90 NM N OF ITCZ BETWEEN 78W AND 80W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM 02N TO 12N BETWEEN 89W AND 101W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM 04N TO 13N BETWEEN 109W AND 123W. SCATTERED MODERATE CONVECTION IS WITHIN 180 NM EITHER SIDE OF THE AXIS BETWEEN 124W AND 136W. ...DISCUSSION... N OF 20N... A DEEP CLOSED LOW N OF THE AREA IS ASSOCIATED WITH A WEAKENING 1011 MB SURFACE LOW NEAR 34N127W...AND A SURFACE TROUGH ENTERING THE NW WATERS NEAR 30N128W AND EXTENDING SOUTHWESTWARD TO 28N131W. THE SURFACE LOW AND TROUGH CONTINUE TO LOSE UPPER SUPPORT AS THE ATTENDANT UPPER LOW IS SEPARATED FROM ANY LARGE-SCALE JET STREAM. THUS...THE PRESSURE GRADIENT AROUND THE SURFACE LOW CONTINUES TO WEAKEN...WITH THE QUIKSCAT PASSES AROUND 03/0230 UTC AND 03/0400 UTC CONFIRMING THAT NW WINDS W OF THE TROUGH ARE IN THE 10 TO 15 KT RANGE. DURING THE NEXT FEW DAYS...SEVERAL UPPER TROUGHS ARE FORECAST TO PIVOT CYCLONICALLY AROUND THE PARENT DEEP LOW N OF THE AREA. DIFFLUENT SOUTHWESTERLY FLOW ALOFT E OF THE UPPER TROUGHS WILL DRIVE SURFACE PRESSURE FALLS AND SURFACE TROUGHING OVER N MEXICO AND THE N GULF OF CALIFORNIA. THE CORRESPONDING PRESSURE GRADIENT IS INCREASING SW WINDS ACROSS THE N GULF OF CALIFORNIA TONIGHT...WHICH ARE INTERACTING WITH DOWNSLOPE FLOW OFF THE BAJA CALIFORNIA COAST TO SUPPORT SW WINDS OF 20 KT. A SIMILAR PATTERN IS EXPECTED OVER THE N GULF OF CALIFORNIA DURING THE NEXT FEW NIGHTS...WITH SW FLOW ALOFT CONTINUING OVER THE N GULF OF CALIFORNIA. THIS WILL OCCUR AS THE AFOREMENTIONED UPPER LOW DRIFTS SOUTHEASTWARD TOWARD THE WESTERN UNITED STATES COAST BEFORE BEING EJECTED EASTWARD OVER THE WESTERN UNITED STATES AS AN OPEN WAVE THIS WEEKEND INTO EARLY NEXT WEEK. THE STRONGEST WINDS OVER THE NORTHERN GULF OF CALIFORNIA ARE FORECAST TO OCCUR THU NIGHT AND FRI NIGHT...WHEN THE UPPER LEVEL HEIGHT GRADIENT AT THE SOUTHERN PERIPHERY OF THE UPPER LEVEL CYCLONE TIGHTENS...YIELDING A 100-110-KT UPPER LEVEL JET MAX S OF THE UPPER LOW...ENHANCING THE DOWNSLOPE FLOW INTO THE N GULF OF CALIFORNIA. THE STRONGEST DOWNSLOPE WINDS ARE EXPECTED AT NIGHT WHEN NOCTURNAL DRAINING FLOW IS MAXIMIZED. THE SURFACE PRESSURE GRADIENT BETWEEN PERSISTENT SURFACE TROUGHING OVER MEXICO AND WEAK SURFACE RIDGING OVER THE E PACIFIC WILL CONTINUE DRIVING NW WINDS AROUND 20 KT NEAR THE W COASTS OF BAJA CALIFORNIA. THESE CONDITIONS WERE EVIDENT FROM THE ASCAT PASS AROUND 03/0415 UTC. S OF 20N... A SURFACE TROUGH EMBEDDED WITHIN THE ITCZ EXTENDS FROM 16N105W TO 11N111W TO 08N113W. THE PRESSURE GRADIENT AROUND THE TROUGH IS RESULTING IN WINDS TO 20 KT FROM 08N TO 14N WITHIN 180 NM E OF THE TROUGH...WITH NE WINDS TO 20 KT FROM 11N TO 16N W OF THE TROUGH TO 124W BASED ON THE ASCAT PASS AROUND 03/0415 UTC. WINDS TO 20 KT WILL IMPACT LOCATIONS AROUND THIS TROUGH DURING THE NEXT TWO DAYS AS IT MOVES WESTWARD AROUND 10 KT. LOW LEVEL CONVERGENCE NEAR THIS TROUGH IS ALSO ENHANCING CONVECTION ASSOCIATED WITH THE ITCZ. THIS CONVECTION IS FURTHER BEING ENHANCED BY DEEP MOISTURE AND UPPER LEVEL DIVERGENCE IN THE VICINITY OF AN UPPER RIDGE S OF 19N BETWEEN 98W AND 120W. FARTHER TO THE W...AN UPPER LEVEL LOW IS CENTERED NEAR 16N133W. UPPER LEVEL DIFFLUENCE IN MOIST SOUTHWESTERLY FLOW ALOFT E OF THE LOW IS ENHANCING SEVERAL AREAS OF CONVECTION OVER WESTERN PORTIONS OF THE DISCUSSION AREA...WITH THE GREATEST CONCENTRATION OF THE STRONGEST CONVECTION NEAR A SURFACE TROUGH EXTENDING FROM 12N134W TO 08N136W. ALSO...THE PRESSURE GRADIENT N OF THE TROUGH IS ENHANCING AN AREA OF NE TO E TRADE WINDS AROUND 20 KT FROM 11N TO 17N W OF 130W BASED ON THE ASCAT PASS AROUND 03/0600 UTC. DURING THE NEXT DAY...THESE TRADES ARE FORECAST TO PERSIST IN THE SAME GENERAL AREA WITH NEARLY THE SAME INTENSITY WITH SURFACE RIDGING FARTHER TO THE N. ENHANCED EASTERLY TRADE WINDS IN THE CARIBBEAN ARE FORECAST TO BLEED INTO THE GULF OF PAPAGAYO DURING THE NEXT TWO DAYS...WHEN NE TO E WINDS OF 20 KT ARE EXPECTED NEAR AND DOWNWIND OF THE GULF OF PAPAGAYO. THEREAFTER...WEAKENING TRADES IN THE CARIBBEAN THIS WEEKEND WILL RESULT IN WINDS FALLING BELOW 20 KT IN THE GULF OF PAPAGAYO. SEAS UP TO 9 FT IN SOUTHWESTERLY SWELL WILL CONTINUE TO OVERTAKE A LARGE PART OF THE DISCUSSION AREA S OF 07N DURING THE NEXT TWO DAYS...DRIVEN BY STRONG WINDS ASSOCIATED WITH SOUTHERN HEMISPHERIC STORM SYSTEMS. $$ COHEN