000 FXUS66 KPQR 051536 AFDPQR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PORTLAND OR 835 AM PDT SUN JUL 5 2009 .SYNOPSIS...THE STRONG UPPER LEVEL RIDGE OVER THE PACIFIC NORTHWEST WILL BEGIN WEAKENING AND MOVING SLOWLY EASTWARD TODAY. AN UPPER LEVEL TROUGH WILL APPROACH THE AREA TONIGHT AND MONDAY...USHERING IN A FAIRLY STRONG MARINE PUSH AND A QUICK 15 TO 20 DEGREE COOL DOWN FOR MOST INLAND AREAS BY MONDAY MORNING. THE UPPER TROUGH WILL BE OVER THE AREA THROUGH ABOUT MID WEEK...THEN ANOTHER UPPER TROUGH WILL DEVELOP OFF THE COAST LATE IN THE WEEK. && .SHORT TERM...SATELLITE IMAGERY SHOWS A SHALLOW MARINE LAYER ALONG THE COAST AND INTO THE COASTAL GAPS...AND UP THE COLUMBIA RIVER AS FAR AS KELSO THIS MORNING...WHICH WILL LIKELY DEEPEN SOME TODAY AND TONIGHT AS AN UPPER UPPER TROUGH OFF THE COAST APPROACHES AND MOVES ONSHORE. THE STRONG UPPER RIDGE OF RECENT DAYS WILL WEAKEN AND MOVE EAST. THE UPPER TROUGH OFFSHORE DOES HAVE SOME HIGHER CLOUDS THAT WILL MOVE INLAND LATER TODAY. THE UPPER TROUGH THEN USHERS IN A RATHER STRONG MARINE PUSH TONIGHT AND MONDAY. THE ONSHORE GRADIENTS LOOK TO BE INCREASING LATE THIS AFTERNOON...AND TEMPS INLAND TODAY SHOULD BE DOWN A COUPLE OF DEGREES FROM THOSE SATURDAY BUT STILL BE QUITE WARM AND WILL MAINTAIN THE CURRENT HEAT ADVISORY. THE MAIN COOL DOWN WILL BE ON MONDAY. THE MODELS INDICATE THAT AS THE UPPER TROUGH COMES ONSHORE TONIGHT THAT THERE IS A CHANCE OF SOME CONVECTION IN THE CASCADES. THERE IS ALSO A LOWER LEVEL BOUNDARY THAT APPROACHES THE COAST LATER TONIGHT AND MOVES ONSHORE MONDAY THAT WILL LIKELY GIVE THE COAST AND COASTAL MOUNTAINS A CHANCE OF SOME DRIZZLE OR LIGHT RAIN LATER TONIGHT AND MONDAY. THE CLOUDS WILL PUSH INLAND BY MONDAY AND LIKELY NOT CLEAR MUCH EXCEPT IN THE SOUTHEAST CORNER OF OUR FORECAST AREA...AND MIGHT EVEN GIVE A FEW SHOWERS OVER THE HIGHER TERRAIN AND IN THE NORTH INTERIOR. INLAND TEMPS WILL BE CLOSER TO 70 ON MONDAY. A SECONDARY DISTURBANCE ROTATES TOWARD THE NORTH COAST LATER MONDAY NIGHT AND ACROSS THE NORTH PART OF OUR FORECAST AREA TUESDAY AND TUESDAY EVENING. THE MAIN IMPACT TUESDAY WILL BE IN THE NORTH NEAR THE TRACK OF THE LOW CENTER. TEMPS WILL REMAIN CLOSE TO 70 AGAIN TUESDAY AS CLOUDS WILL TEND TO PERSIST MOST AREAS. LIKENS .LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...THE UPPER TROUGH PERSISTS INTO WEDNESDAY...FOLLOWED BY ANOTHER FOR THE LATTER PART OF THE WEEK SETTING UP OFF THE COAST. THIS WILL GENERALLY KEEP TEMPS A BIT BELOW NORMAL...WITH A FAIR AMOUNT OF CLOUD COVER...AND A SHOWER OR TWO AT TIMES. && .AVIATION...CEILINGS HAVE LIFTED TO MVFR THIS MORNING ALONG THE COAST IN RESPONSE TO AN APPROACHING SHORTWAVE TROUGH. CONDITIONS WILL FALL BACK TO IFR IN LOCAL LIGHT RAIN OR DRIZZLE LATER TONIGHT. ISOLATED THUNDERSTORMS ARE POSSIBLE OVER THE CASCADES THIS EVENING. ELSEWHERE...VFR CONDITIONS ARE EXPECTED TODAY. LATE TONIGHT AND EARLY MONDAY MORNING THE MARINE LAYER SHOULD DEEPEN ENOUGH TO ALLOW MVFR STRATUS TO PUSH INTO THE WILLAMETTE VALLEY. KPDX AND APPROACHES...NO SIGNIFICANT WEATHER IMPACTS EXPECTED TODAY THROUGH MUCH OF TONIGHT. AFTER 10Z MONDAY MORNING MVFR CEILINGS WILL LIKELY DEVELOP IN DEEP ONSHORE FLOW. && .MARINE...SEAS WILL CONTINUE AROUND 5 FT FOR THE NEXT FEW DAYS. SOUTH WINDS WILL INCREASE ACROSS THE WATERS TONIGHT THROUGH MONDAY AS A WEAK PACIFIC SYSTEM MOVES ACROSS. HOWEVER...WINDS SHOULD REMAIN BELOW SMALL CRAFT CRITERIA. QUIET WEATHER IS EXPECTED THROUGH THE WEEK. && .PQR WATCHES/WARNINGS/ADVISORIES... OR/WA...HEAT ADVISORY THROUGH THIS EVENING FOR THE COAST RANGE...INLAND VALLEYS AND CASCADE FOOTHILLS. && $$ MORE WEATHER INFORMATION ONLINE AT... HTTP://WEATHER.GOV/PORTLAND THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY REFERRED TO AS THE FORECAST AREA.