000 AXPZ20 KNHC 040918 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC THU JUN 04 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 0900 UTC. ...TROPICAL WAVE... A TROPICAL WAVE IS ALONG 81W/82W N OF 4N MOVING W AT 10 TO 15 KT. THE TOTAL PRECIPITABLE WATER PRODUCT FROM CIMSS INDICATES THAT THIS WAVE COINCIDES WITH A MAXIMUM IN DEEP LAYER MOISTURE. SATELLITE IMAGERY INDICATES THAT THE WAVE ALSO COINCIDES WITH AN INVERTED-V SIGNATURE IN THE LOW LEVEL CLOUD FIELD. THE CIMSS WAVETRAK PRODUCT ALSO DEPICTS LOW LEVEL CYCLONIC CIRCULATION NEAR THE WAVE. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM 04N TO 08N E OF 83W INCLUDING THE GULF OF PANAMA. THIS CONVECTION HAS RECENTLY SHOWN SIGNS OF INTENSIFICATION AS THE WAVE INTERACTS WITH UPPER LEVEL DIVERGENCE E OF AN UPPER LEVEL RIDGE OVER SE PORTIONS OF THE DISCUSSION AREA...AS WELL AS LOW LEVEL CONVERGENCE DRIVEN BY NOCTURNAL DRAINAGE FLOW. ...ITCZ... AXIS FROM 08N83W TO 08N105W TO 12N110W TO 09N125W TO 05N140W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM 05N TO 08N BETWEEN 83W AND 87W. SCATTERED MODERATE CONVECTION IS FROM 06N TO 12N BETWEEN 89W AND 108W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM 11N TO 18N BETWEEN 110W AND 118W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM 05N TO 18N BETWEEN 118W AND 131W. ...DISCUSSION... N OF 20N... A DEEP CLOSED LOW N OF THE AREA IS ASSOCIATED WITH A WEAKENING 1014 MB SURFACE LOW NEAR 36N126W...AND A SURFACE TROUGH ENTERING THE NW WATERS NEAR 30N125W AND EXTENDING SOUTHWESTWARD TO 28N127W. 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 PASS AROUND 04/0330 UTC DEPICTING NW TO N WINDS TO THE W OF THE TROUGH 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 FRI NIGHT AND SAT NIGHT...WHEN THE UPPER LEVEL HEIGHT GRADIENT AT THE SOUTHERN PERIPHERY OF THE UPPER LEVEL CYCLONE TIGHTENS...YIELDING A 90-100-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 SURFACE RIDGING OVER THE E PACIFIC WILL CONTINUE DRIVING NW WINDS AROUND 20 KT NEAR THE W COAST OF BAJA CALIFORNIA. PEAK WINDS NEAR THE S AND W COASTS OF BAJA CALIFORNIA ARE FORECAST TO INCREASE TO 20-25 KT DURING THE NEXT TWO DAYS AS A SURFACE RIDGE STRENGTHENS OVER THE CENTRAL PACIFIC WEST OF THE AFOREMENTIONED SURFACE LOW AND SURFACE TROUGH. THIS INCREASED RIDGING WILL BE SUPPORTED BY AN AMPLIFYING UPPER LEVEL RIDGE OVER THE CENTRAL AND N PACIFIC THIS WEEKEND. ALSO DURING THE WEEKEND...THE AFOREMENTIONED UPPER LOW WILL MERGE WITH AN UPPER LOW OVER THE NORTHERN ROCKIES LEAVING BEHIND A MID-LEVEL VORTICITY MAXIMUM NW OF THE DISCUSSION AREA. THIS FEATURE WILL CORRESPOND TO A DEEP CLOSED LOW THAT COULD DRIFT SOUTHWARD INTO THE NW PORTIONS OF THE DISCUSSION AREA LATE THIS WEEK INTO THE WEEKEND...AS THE UPSTREAM RIDGE FOLDS OVER THE DEEP LOW. THE EXACT TRACK OF THE SURFACE LOW IS RATHER UNCERTAIN...THOUGH THE SURFACE LOW MIGHT DRAG A COLD FRONT INTO THE FAR NW WATERS BY LATE SUN INTO MON MORNING...WITH WINDS OF 15 TO 20 KT AROUND THE LOW AND BEHIND THE COLD FRONT. S OF 20N... A SURFACE TROUGH EMBEDDED WITHIN THE ITCZ EXTENDS FROM 17N109W TO 11N115W. THE PRESSURE GRADIENT AROUND THE TROUGH IS RESULTING IN WINDS TO 20 KT NEAR THE TROUGH BASED ON THE QUIKSCAT PASS AROUND 04/0200 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 LAYER MOISTURE AND UPPER LEVEL DIVERGENCE IN THE VICINITY OF A LARGE UPPER RIDGE S OF 26N BETWEEN 92W AND 127W. FARTHER TO THE W...UPPER LEVEL DIFFLUENCE IN MOIST SOUTHWESTERLY FLOW ALOFT E OF AN UPPER TROUGH EXTENDING FROM 22N127W TO 13N132W IS ENHANCING A LARGE AREA OF CONVECTION ASSOCIATED WITH A SURFACE TROUGH EMBEDDED WITHIN THE ITCZ. THIS SURFACE TROUGH EXTENDS FROM 13N121W TO 09N127W TO 06N129W. ALSO...THE PRESSURE GRADIENT N OF THE TROUGH IS ENHANCING AN AREA OF NE TRADE WINDS AROUND 20 KT FROM 09N TO 16N W OF 127W BASED ON THE QUIKSCAT PASS AROUND 04/0345 UTC AND THE ASCAT PASS AROUND 04/0530 UTC. DURING THE NEXT DAY...THESE TRADES ARE FORECAST TO EXPAND EASTWARD DUE TO THE INFLUENCE OF THE WESTERN SURFACE TROUGH. ENHANCED EASTERLY TRADE WINDS IN THE CARIBBEAN ARE FORECAST TO BLEED INTO THE GULF OF PAPAGAYO DURING THE NEXT DAY...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 PORTIONS OF THE DISCUSSION AREA S OF 14N...DRIVEN BY STRONG WINDS ASSOCIATED WITH SOUTHERN HEMISPHERIC STORM SYSTEMS. $$ COHEN