012 FXUS66 KPDT 241826 AAB AFDPDT AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE PENDLETON OR 1025 AM PST TUE NOV 24 2015 UPDATED AVIATION DISCUSSION TO ADD MORE DETAIL .SHORT TERM...UPPER LOW MOVING ACROSS THE PACIFIC NORTHWEST TODAY AND TONIGHT. CENTER OF THE LOW IS JUST OFF THE OREGON COAST THIS MORNING. SATELLITE SHOWING OVERCAST CONDITIONS ACROSS THE FORECAST AREA. PRECIPITATION IS MIXED WITH REPORTS OF RAIN FREEZING RAIN AND SNOW AS TEMPERATURES ARE IN THE UPPER 20S TO LOWER 30S. AS THE LOW CONTINUES TO MOVE SOUTH TODAY COLDER AIR WILL ADVECT INTO THE REGION WITH INCREASING NORTHERLY WINDS. THIS WILL RESULT IN PRECIPITATION CHANGING OVER TO ALL SNOW BY EVENING AND TONIGHT. WITH THE LOW CENTERED OVER SOUTHERN OREGON AND NORTHERN CALIFORNIA TONIGHT EXPECT SIGNIFICANT SNOW FOR CENTRAL AND NORTHEAST OREGON THROUGH EARLY WEDNESDAY MORNING. CLEARING SKIES LATER WEDNESDAY AS HIGH PRESSURE STARTS TO BUILD IN WITH A DRY COLD NORTH FLOW. 94 && .AVIATION...18Z TAFS...THE WARM LAYER ALOFT THAT HAD ALLOWED RAIN TO REACH THE GROUND THIS MORNING IN THE LOWER COLUMBIA BASIN PRODUCING FREEZING RAIN AT THE SURFACE HAS COOLED TO BELOW FREEZING AND THE FORECAST VERTICAL TEMPERATURE PROFILE FOR THE COLUMBIA BASIN AND SURROUNDING HIGHER TERRAIN WILL REMAIN BELOW FREEZING THROUGH THE REST OF THIS STORM EVENT. THUS SNOW IS EXPECTED AT TAF SITES FROM THIS POINT FORWARD FOR THE REMAINDER OF TODAY AND THROUGH THIS EVENING FOR ANY PRECIPITATION THAT DOES OCCUR. CONDITIONS AT KRDM AND KBDN ARE DOWN TO LIFR/IFR VIS DUE TO -SN/SN AND THESE CONDITIONS ARE ALSO EXPECTED AT KPDT, KALW AND KDLS WITH THESE CONDITIONS PERSISTING THROUGH THIS AFTERNOON INTO THIS EVENING. CONDITIONS HAVE ALSO DETERIORATED TO IFR AT KPSC DUE TO LOW CIGS WITH -SN LIMITING VIS TO AROUND 3SM THROUGH THIS AFTERNOON. SNOW HAS ENDED AT KYKM FOR TODAY, ALTHOUGH MVFR VIS ARE POSSIBLE AT KYKM DUE TO MIST THIS AFTERNOON. IN SUMMARY, LOW CLOUDS/FOG AND SNOW CONTINUING AT MOST TAF SITES THROUGH THIS EVENING. NORTHERLY FLOW IN THE BOUNDARY LAYER WILL CAUSE LOW CLOUDS AND SNOW TO PERSIST AT KALW AND KPDT THROUGH THIS EVENING. MOST SITES WILL IMPROVE AFTER 25/06Z. WINDS WILL BE NORTHERLY AND INCREASE THIS AFTERNOON AND EVENING TO 10-20 KTS AND THESE WINDS SPEEDS WILL CONTINUE THROUGH 18Z TOMORROW MORNING. POLAN && .PREVIOUS DISCUSSION... /ISSUED 343 AM PST TUE NOV 24 2015/ SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT...AN UPPER LEVEL LOW WEST OF VANCOUVER ISLAND WILL MOVE SOUTH OFF THE COAST THIS MORNING...THEN MOVE SOUTHEAST ACROSS NORTHERN CALIFORNIA AND NEVADA TONIGHT AND WEDNESDAY. THIS WILL KEEP A MIX OF RAIN...FREEZING RAIN...AND SNOW ACROSS EASTERN WASHINGTON AND OREGON TODAY. WRAPAROUND MOISTURE WILL KEEP SNOW ACROSS THE AREA THIS EVENING. HIGH PRESSURE WILL BUILD INTO SOUTHEAST WASHINGTON WEDNESDAY. COLD AIR IS TRAPPED IN THE LOWER COLUMBIA BASIN WITH AREAS OF LIGHT FREEZING RAIN. FREEZING RAIN OR UNKNOWN PRECIP WITH BELOW FREEZING TEMPERATURES HAVE BEEN REPORTED YKM, PSC, PDT, ALW, DLS, AND PROSSER. TEMPERATURES AT MOST STATIONS IN THE COLUMBIA RIVER GORGE HAVE RISEN ABOVE FREEZING BUT POCKETS OF COLDER AIR PROBABLY REMAIN. ALL OTHER ZONES IN THE FREEZING RAIN ADVISORY STILL HAVE MAINLY BELOW FREEZING TEMPERATURES. I WILL CONTINUE THE FREEZING RAIN ADVISORIES AT THIS TIME. SNOW OR RAIN CHANGING TO SNOW IS EXPECTED TO SPREAD ACROSS NORTHEAST OREGON EARLY THIS MORNING. SNOW ADVISORIES ARE WILL START THIS MORNING OVER ALL OREGON ZONES NOT COVERED BY FREEZING RAIN ADVISORIES. A BACKDOOR ARCTIC FRONT WILL BRING DRIER AND MORE STABLE COLD AIR WILL MOVE INTO NORTHERN WASHINGTON THIS EVENING AND SPREAD ACROSS OREGON WEDNESDAY. SNOW WILL END OVER SOUTHEAST WASHINGTON EARLY WEDNESDAY AND OVER OREGON BY WEDNESDAY NIGHT. BRISK NORTHERLY WINDS WILL DEVELOP BEHIND THIS FRONT AND PERSIST WEDNESDAY EVENING. COONFIELD LONG TERM...THURSDAY THROUGH TUESDAY...DRY WEATHER WILL PREVAIL THROUGH THE THANKSGIVING WEEKEND...BUT A NORTHEASTERLY FLOW ALOFT WILL KEEP TEMPERATURES BELOW NORMAL. HIGH TEMPERATURES WILL BE IN THE 20S TO MID 30S AND OVERNIGHT LOWS WILL BE IN THE SINGLE DIGITS TO LOWER 20S. A SURFACE INVERSION WILL DEVELOP THURSDAY NIGHT AS A RIDGE BUILDS OVER WASHINGTON. THE LONG CLEAR NIGHT AND LIGHT WINDS WILL CREATE IDEAL CONDITIONS FOR PATCHY FREEZING FOG AND STRATUS DEVELOPMENT IN THE LOWER COLUMBIA BASIN AND MOUNTAIN VALLEYS. THE FOG COULD LAST THROUGH MONDAY...BUT AM NOT CONFIDENT IN THIS. A LOBE OF ENERGY ASSOCIATED WITH THE CUTOFF LOW THAT BROUGHT SNOW TO THE REGION COULD LINGER AND LESSEN THE CHANCES OF A PERSISTENT FOG BY BRINGING CLOUDS TO THE AREA AND POSSIBLE EVEN SNOW SHOWERS. HOWEVER...HAVE KEPT THE FORECAST DRY AND FOGGY FOR NOW. THE NEXT CHANCE FOR RAIN AND SNOW WILL BE MONDAY NIGHT AND TUESDAY. SLIGHTLY WARMER TEMPERATURES CAN ALSO BE EXPECTED TUESDAY. COBB && .PRELIMINARY POINT TEMPS/POPS... PDT 35 25 32 12 / 70 60 20 0 ALW 38 26 35 15 / 70 60 10 0 PSC 38 28 39 17 / 70 50 10 0 YKM 37 25 38 14 / 60 40 0 0 HRI 38 28 38 14 / 70 50 10 0 ELN 35 22 34 13 / 60 30 0 0 RDM 38 18 26 5 / 80 80 30 0 LGD 40 25 29 12 / 80 60 30 0 GCD 40 22 28 8 / 80 70 40 10 DLS 40 29 40 19 / 70 60 10 0 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...WINTER WEATHER ADVISORY UNTIL 4 AM PST WEDNESDAY FOR ORZ049-050- 502-503-505-506-509-511. FREEZING RAIN ADVISORY UNTIL 10 AM PST THIS MORNING FOR ORZ041- 044-507-508-510. WA...WINTER WEATHER ADVISORY UNTIL 4 AM PST WEDNESDAY FOR WAZ030. FREEZING RAIN ADVISORY UNTIL 10 AM PST THIS MORNING FOR WAZ024- 027>029. WINTER WEATHER ADVISORY UNTIL 3 PM PST THIS AFTERNOON FOR WAZ520. && FOR ADDITIONAL WEATHER INFORMATION, CHECK OUR WEB SITE AT... WWW.WEATHER.GOV/PENDLETON $$ 94/99/76/82