359 FXUS66 KPQR 011638 AFDPQR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PORTLAND OR 830 AM PST THU JAN 01 2004 .SYNOPSIS...COLD WINTER WEATHER EXPECTED IN THE FORECAST AREA INTO NEXT WEEK. A PAC LOW IS MOVING THROUGH SOUTHWEST OREGON THIS MORNING AND WILL MOVE INTO NORTHEAST OREGON THIS AFTERNOON...BRINGING MORE RAIN AND SNOW ALONG WITH LOW SNOW LEVELS IN THE NORTH. ONSHORE FLOW BEHIND THIS SYSTEM WILL KEEP SHOWERS WITH LOW SNOW LEVELS CONTINUING THROUGH SAT. SOME MODIFIED ARCTIC AIR MAY MOVE INTO THE AREA SAT NIGHT. MODELS CONTINUE TO SHOW A CHANCE OF LOW ELEVATION SNOW NEXT WEEK AS SYSTEMS APPROACH FROM THE SOUTHWEST. && .DISCUSSION... .SHORT TERM...SATELLITE IR AND WATER VAPOR LOOPERS SHOW THE SURFACE LOW MOVING ONSHORE ABOUT 12Z NEAR GOLD BEACH...TO SOUTH OF THE WILLAMETTE VALLEY CURRENTLY. PRES FALLS SUPPORT GFS AND MESO ETA MODEL TRACKS THROUGH REDMOND THIS MORNING INTO NORTHEAST OREGON THIS AFTERNOON. NATIONAL WEATHER SERVICE DOPPLER RADAR SHOWS INITIAL BAND OF PRECIP FROM CORVALLIS THROUGH PORTLAND WITH A SECOND BAND FROM EUGENE THROUGH MT HOOD. HAVE ISSUED A WINTER STORM WARNING FOR THE CENTRAL AND SOUTHERN WILLAMETTE VALLEY WITH REPORTS OF 2 TO 3 INCHES THERE ALREADY...A SNOW ADVISORY FOR THE CENTRAL COASTAL RANGE AND HAVE CHANGED THE WINTER WEATHER ADVISORY FOR THE PORTLAND METRO AREA TO A SNOW ADVISORY BECAUSE THE FREEZING RAIN HAS ENDED. WILL NEED TO WATCH THE OREGON CASCADES AND THE COLUMBIA RIVER GORGE FOR POSSIBLE HIGHER AMOUNTS THAN THE CURRENT ADVISORY LEVELS WE HAVE FOR THOSE AREAS. ONSHORE FLOW AROUND RESIDUAL LOW PRESSURE OFF THE WA COAST TONIGHT AND FRI WILL KEEP SHOWERS GOING. WILL HAVE A SHOT AT ADVISORY AMOUNTS IN THE MOUNTAINS...BUT IFFY IN THE VALLEYS. THICKNESS VALUES SUGGEST THE SNOW LEVEL COULD BE CLOSE TO THE VALLEY FLOOR. A SHORT WAVE DROPPING SOUTH THROUGH B.C. AND ACROSS THE PACIFIC NORTHWEST LATER FRI NIGHT AND SAT INTENSIFIES THE LOW LEVEL ONSHORE FLOW FOR POTENTIAL SNOW ADVISORY AMOUNTS EVEN AT LOWER ELEVATIONS. MODIFIED ARCTIC AIR BEHIND THE SHORT WAVE SHOULD FILTER INTO THE AREA SAT NIGHT. LIKENS .LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...00Z GFS RUN HAS BEEN CONSISTENT WITH ITSELF AND THE ECMWF...AT LEAST WITHIN REASON...FOR THE PAST FEW RUNS. MODIFIED ARCTIC AIR DROPS DOWN OVER WRN OREGON/WA ON SAT AND REMAINS IN PLACE AS STRONG DEEP LOW PRESSURE SYSTEM MOVES TOWARD US SUN NIGHT AND MON. TRACK OF THIS LOW IS UNCERTAIN BUT CURRENT MODELS KEEP THE LOW JUST SOUTH OF OUR CWA. WILL BEGIN TO NUDGE FORECAST TOWARD A SNOW AND CHANCE OF FREEZING RAIN FOR AT LEAST THE NORTHERN ZONES OF OUR CWA. SCHNEIDER && .PRELIMINARY POINT POPS AST 76677 PDX 86677 SLE +6677 EUG +6677 && .PQR WATCHES/WARNINGS/ADVISORIES... .WA/OR...SNOW ADVISORY...NORTH AND CENTRAL OREGON CASCADES AND FOOTHILLS...WESTERN COLUMBIA GORGE...KPDX METRO AREA... CENTRAL COAST RANGE TODAY. .WA/OR...WINTER STORM WARNING...CENTRAL AND SOUTHERN WILLAMETTE VALLEY THIS MORNING. .WA/OR...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS CAPE SHOALWATER TO FLORENCE. $$