FXUS66 KPQR 201005 AFDPQR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PORTLAND OR 230 AM PST TUE JAN 20 2009 .SYNOPSIS...A STRONG UPPER LEVEL RIDGE WILL CONTINUE TO DOMINATE THE PACIFIC NORTHWEST THROUGH TODAY...CENTERED NEAR IDAHO. THE UPPER RIDGE WILL THEN WEAKEN AND MOVE OFF TO THE EAST FOR THE REMAINDER OF THE WEEK. THE STRONG SURFACE HIGH PRESSURE AREA EAST OF THE CASCADES WILL ALSO WEAKEN...ESPECIALLY TUESDAY NIGHT AND WEDNESDAY WITH DECREASING EAST WINDS. THE FIRST PACIFIC WEATHER SYSTEM TO APPROACH IN QUITE SOME WHILE WILL SPLIT AND WEAKEN AS IT NEARS THE COAST WEDNESDAY NIGHT AND THURSDAY...THEN EVENTUALLY PUSH THROUGH OUR FORECAST AREA ABOUT FRIDAY. A SERIES OF WEATHER SYSTEMS MAY BEGIN PUSHING THROUGH THE PACIFIC NORTHWEST THIS WEEKEND AND EARLY NEXT WEEK AS THE UPPER AIR PATTERN FINALLY CHANGES. && .SHORT TERM...THE KTTD-KDLS OFFSHORE PRESSURE GRADIENT HAS FINALLY FALLEN TO LESS THAN 10 MB THIS MORNING...BUT THE DECREASE IS SLOW AND WINDS ARE STILL QUITE GUSTY THIS MORNING IN AND NEAR THE COLUMBIA RIVER GORGE AND IN THE EAST COUNTY AREAS THOUGH WIND SPEEDS HAVE FALLEN BELOW ADVISORY CRITERIA AND WILL CONTINUE TO DIMINISH TODAY. TROUTDALE WAS STILL GUSTING TO AROUND 30 MPH THIS MORNING. DEWPOINTS REMAIN VERY LOW ACROSS THE FORECAST AREA THIS MORNING AND THINK THE BEST CHANCE OF ANY FOG WILL BE DOWN NEAR EUGENE AND POSSIBLY UP NEAR CASTLE ROCK...BUT THEN PATCHY AT BEST ANYWHERE ELSE. WINDS WILL LET UP A LOT MORE TONIGHT AND WEDNESDAY AND THINK THE FOG WILL BEGIN EXPANDING MORE THEN. THE SURFACE PRESSURE GRADIENT IS STILL OFFSHORE THROUGH THE GORGE AROUND 6 OR 7 MB ON THE NAM12 TONIGHT AND WEDNESDAY...SO THERE WILL STILL BE SOME WIND IN THE GORGE AND NEAR TROUTDALE. THAT WOULD STILL SUPPORT PEAK GUSTS OF 40 TO 50 MPH IN THE GORGE. PRESSURE GRADIENTS LET UP TO AROUND 5 MB WEDNESDAY NIGHT WITH GUSTS UP TO 30 OR 35 MPH TOPS IN THE GORGE. EXPECT MORE FOG IN THE VALLEYS WEDNESDAY NIGHT AS WELL. THE GRADIENTS ARE WEAKENING AS THE UPPER RIDGE WEAKENS AND THE FIRST PACIFIC WEATHER SYSTEM IN QUITE SOME TIME APPROACHES...BUT THAT FRONT WILL BE SPLITTING AND WEAKENING AS IT APPROACHES. THE SOUTHERN PART HEADS TOWARD CALIFORNIA. THE NORTHERN PART SETS UP OFF THE WASHINGTON AND OREGON COAST WEDNESDAY NIGHT AND THURSDAY. AS IT DOES...A MARINE LAYER MAY DEVELOP ALONG THE COAST FROM THE SOUTH LATE WEDNESDAY AND THURSDAY. SOME MOISTURE FROM THE SOUTHERN PART OF THIS SPLITTING SYSTEM MAY LIFT BACK NORTH THROUGH CENTRAL AND EASTERN OREGON AND MAY BRUSH A PART OF OUR AREA. ADDED A SLIGHT CHANCE OF SHOWERS TO THE LANE COUNTY CASCADES THEN. THE LEFTOVER NORTHERN LOW MAY FINALLY MOVE ONSHORE AROUND FRIDAY... THOUGH LOOKS LIKE IT WILL MOVE SOUTH ALONG THE COAST. WILL NOT MAKE ANY CHANGES FOR THAT YET. WILLSON .LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS... A LOT OF UNCERTAINTY IN THE EXTENDED FORECAST. LATEST RUNS OF THE ECMWF AND GFS TRY TO SHOW A PATTERN CHANGE BEGINNING SAT. ENSEMBLE FORECASTS SHOW A WIDE RANGE OF SOLUTIONS FOR DAYS 5-7. THERE ARE HINTS THAT A RETURN TO A COLDER AND MORE ACTIVE PATTERN WILL OCCUR SUN AND CONTINUE THROUGH EARLY NEXT WEEK. WOULD TEND TO LEAN TOWARD THE ECMWF MODEL FOR THE EXTENDED BASED ON ITS PAST PERFORMANCE. HEDGED MORE TOWARD CLIMO POPS STARTING SUN. WEISHAAR && .AVIATION...DRY OFFSHORE FLOW CONTINUES...WITH MAINLY VFR CONDITIONS PREVAILING THIS MORNING. ONLY EXCEPTION MAY BE SOME PATCHY FG/FZFG IN THE INTERIOR VALLEYS AWAY FROM THE GORGE AS WINDS GO CALM. GUSTS 35-45 KT CONTINUE NEAR THE WEST END OF THE GORGE...WITH GUSTS TO 30-35 KT CONTINUING NEAR KTTD. AIRCRAFT SOUNDINGS SUGGEST CORE OF STRONG WINDS IS MAINLY CONFINED TO 2000 FT MSL AND BELOW...WITH MUCH LIGHTER SE FLOW ABOVE. WINDS EASE SLIGHTLY TODAY...BUT GUSTS 25-30 KT STILL POSSIBLE AT KTTD THROUGH THE DAY. KPDX AND APPROACHES...VFR CONDITIONS PREVAIL TODAY. WINDS ARE EASING AT KPDX...BUT JUST EAST OF THE RUNWAYS GORGE WINDS CONTINUE WITH EAST WIND GUSTS 25-35 KT NEAR KTTD. EXPECT SOME SLIGHT EASING IN THESE WINDS AS THE DAY PROGRESSES. && .MARINE...STRONG HIGH PRESSURE OVER THE INLAND NORTHWEST IS BEGINNING TO WEAKEN...BUT OFFSHORE FLOW CONTINUES TO PRODUCE LOCALLY GUSTY WINDS TO 25 KT BELOW GAPS AND COASTAL CANYONS THIS MORNING. AS HIGH PRESSURE WEAKENS EXPECT WINDS TO EASE OVER THE NEXT 24 HOURS. VERY WEAK DISTURBANCE WILL TRACK UP THE OREGON COAST WED...POSSIBLY CAUSING A SHIFT TO LIGHT-MODERATE S-SE WINDS FOR THE COASTAL WATERS. SEAS EXPECTED TO REMAIN BELOW 10 FT THROUGH AT LEAST FRIDAY. WEAGLE && .PQR WATCHES/WARNINGS/ADVISORIES... OR/WA...AIR STAGNATION ADVISORY UNTIL WED MORNING FOR SOUTH WILLAMETTE VALLEY...THE UPPER HOOD RIVER VALLEY...THE WESTERN COLUMBIA RIVER GORGE NEAR HOOD RIVER...AND THE LOWER COLUMBIA AND I5 CORRIDOR OF SW WASHINGTON && $$ 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.