000 FXUS66 KPQR 212229 AFDPQR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PORTLAND OR 230 PM PST FRI NOV 21 2003 .SYNOPSIS...UPPER TROUGH MOVES INTO ROCKIES OVERNIGHT WITH NORTH FLOW ALOFT INCREASING. SHORT WAVE OVER CENTRAL OREGON THIS EVENING MOVES SOUTH TAKING PRECIPITATION OVER SOUTH OF AREA. HIGH PRESSURE BUILDS IN FROM THE PACIFIC BY SATURDAY MORNING BRINGING MOIST LOW LEVEL AIR MASS. HIGH PRESSURE SHIFTS INTO IDAHO BY SUNDAY. NON PRECIPITATION PATTERN CONTINUES THOUGH MOIST LOW LEVEL AIR MASS REMAINS. NEXT PACIFIC FRONT APPROACHES LATE SUNDAY MOVING OVER AREA MONDAY. A SERIES OF FRONTAL SYSTEMS WILL FOLLOW DURING THE WEEK WITH A FAIRLY VIGOROUS SYSTEM TUESDAY AND WEDNESDAY. && .DISCUSSION... .SHORT TERM...FINAL SHORT WAVE OVER CENTRAL ORE MOVES INTO NRN CA BY LATER TONIGHT AND INCREASES N FLOW ALOFT. THIS ENDS PRECIPITATION PATTERN HOWEVER DRY CANADIAN HIGH PRES STAYS MAINLY N OF AREA ALLOWING MARINE HIGH PRES TO BUILD OVER AREA. LOTS OF CLOUDS CURRENTLY OVER AREA WILL NOT BREAK MUCH THIS EVE EXCEPT COAST AND WITH MORE OF A MARINE AMS OVER AREA LOW CLOUDS/FOG DEVELOPS TONIGHT. THIS WILL KEEP TEMPS TONIGHT FROM GETTING EXTREMELY COLD THOUGH MOST AREA STILL BELOW FREEZING. MAV GUIDANCE LOOKS TOO COOL TONIGHT AND SAT NIGHT AND WILL KEEP LOW TEMPS CLOSE TO MET. HIGHS PRES OVER AREA SAT SHIFTS INTO IDA BY SUN. WEAK FLOW OVER AREA SAT KEEPS LOW CLOUDS/FOG OVER INLAND VALLEYS WITH COAST CLEARING BY AFTERNOON AND MOUNTAINS FAIRLY SUNNY. AS HIGH SHIFTS E SUN MORE CLOUDS DEVELOP ALONG E SLOPES OF CASCADES. HIGH PRES OVER IDA SUN KEEPS LOW LEVEL FLOW FAIRLY LIGHT. THIS KEEPS LOW CLOUDS/AND FOG MOST OF DAY HOWEVER ENOUGH E FLOW WILL BREAK AREAS ALONG COL RIVER. PAC FRONT WILL START PUSHING CLOUDS INTO N PART OF AREA SUN AFTERNOON BUT WILL HOLD PRECIPITATION OFF UNTIL SUN NIGHT. WITH HIGH PRES MORE OF MARINE ORIGINS AND MOVES INTO GT BASIN IT WILL ONLY PICK UP LOCAL CHARACTERISTICS OF ERN BASINS RATHER THEN COLD AMS FROM CANADIAN HIGH. WITH THIS IN MIND DONT FEEL SNOW THREAT W OF GORGE LIKELY SUN NIGHT AND EARLY MON AS PAC FRONT MOVES IN. GORGE MAY GET CLOSE AND WILL START PRECIPITATION AS MIXED BUT WOULD LIKE TO SEE COLDER AMS E SIDE BEFORE GOING FOR SIG SNOW GORGE. FRONT MOVES ACROSS AREA MON AND SHOULD BE E OF AREA BY LATE IN THE DAY. FLOW SHIFTS ONSHORE BEHIND FRONT TURNING PRECIPITATION TO SHOWERS AND ENDING ANY SNOW THREAT FOR GORGE. KOSOVITZ && .LONG TERM...TUESDAY THROUGH FRIDAY SHAPING UP TO BE AN ACTIVE WEATHER PERIOD. GFS MODEL TIMING IS VARYING FROM PREVIOUS SOLUTIONS BUT THE EFFECT IS STILL THE SAME FOR THE HOLIDAY TRAVEL CRUSH. WARM FRONT FORECAST TO MOVE IN ON TUESDAY WILL BOOST THE FREEZING LEVEL OVER THE AREA WHILE PRODUCING PLENTY OF SNOW IN THE CASCADES WITH THE HEAVIEST AMOUNTS AT HIGHWAY PASS LEVELS AND SKI AREAS. A BRIEF BREAK IN THE PRECIPITATION IS POSSIBLE EARLY WEDNESDAY BEFORE THE FOLLOWING COLD FRONT SETTLES TOWARD US WEDNESDAY AFTERNOON. TIMING IS UNCERTAIN. NEVERTHELESS, THE AIRMASS BEHIND THE FRONT ON THANKSGIVING DAY LOOKS LIKE IT IS CHILLY ENOUGH TO PRODUCE SNOW SHOWERS DOWN TO THE FOOTHILLS OF THE CASCADES AND COAST RANGE. AFTER THAT, THE GFS INDICATES THE POTENTIAL FOR THE WHOLE SCENARIO TO REPEAT ITSELF OVER THE HOLIDAY WEEKEND. SALTENBERGER && PRELIMINARY POINT POPS... AST 100188 PDX 100178 SLE 100178 EUG 400168 && .PQR WATCHES/WARNINGS/ADVISORIES... .WA/OR...SMALL CRAFT ADVISORY FOR HAZARDOUS SEA THIS EVENING. && $$