Hazardous Weather Outlook
HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE PENDLETON OR
255 PM PST WED DEC 30 2009
UPDATED FOR WINTER WEATHER TOMORROW
ORZ041>044-049-050-501>506-WAZ024-026>030-501-502-311415-
EASTERN COLUMBIA RIVER GORGE OF OREGON-NORTH CENTRAL OREGON-
CENTRAL OREGON-LOWER COLUMBIA BASIN OF OREGON-GRANDE RONDE VALLEY-
WALLOWA COUNTY-FOOTHILLS OF THE BLUE MOUNTAINS OF OREGON-
NORTHERN BLUE MOUNTAINS OF OREGON-
SOUTHERN BLUE MOUNTAINS OF OREGON-
NORTHERN WHEELER AND SOUTHERN GILLIAM COUNTIES-JOHN DAY BASIN-
OCHOCO-JOHN DAY HIGHLANDS-
EASTERN COLUMBIA RIVER GORGE OF WASHINGTON-KITTITAS VALLEY-
YAKIMA VALLEY-LOWER COLUMBIA BASIN OF WASHINGTON-
FOOTHILLS OF THE BLUE MOUNTAINS OF WASHINGTON-
NORTHWEST BLUE MOUNTAINS-
EAST SLOPES OF THE CENTRAL CASCADES OF WASHINGTON-
EAST SLOPES OF THE SOUTHERN CASCADES OF WASHINGTON-
255 PM PST WED DEC 30 2009
THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL AND NORTHEAST OREGON
AS WELL AS SOUTH CENTRAL AND SOUTHEAST WASHINGTON.
.DAY ONE...TONIGHT
AIR STAGNATION ADVISORY TODAY AND TONIGHT
YAKIMA VALLEY
VERY LIGHT OR CALM SURFACE WINDS AND A STRONG SURFACE BASED
TEMPERATURE INVERSION WILL MAINTAIN A STABLE AIRMASS AND STAGNANT
AIR CONDITIONS...WHICH WILL TRAP AIR POLLUTANTS IN THE YAKIMA
VALLEY. AN AIR STAGNATION ADVISORY IS IN EFFECT FOR THE YAKIMA
VALLEY UNTIL 10 AM PST THURSDAY MORNING. PLEASE REFER TO PDXNPWPDT
FOR DETAILS.
.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY
WINTER MIX THURSDAY
EAST SLOPES OF THE CENTRAL CASCADES OF WASHINGTON, EAST SLOPES
OF THE SOUTHERN CASCADES OF WASHINGTON, EASTERN COLUMBIA RIVER
GORGE OF WASHINGTON, KITTITAS VALLEY, YAKIMA VALLEY, LOWER
COLUMBIA BASIN OF WASHINGTON, EASTERN COLUMBIA RIVER GORGE OF
OREGON, NORTH CENTRAL OREGON, CENTRAL OREGON, LOWER COLUMBIA
BASIN OF OREGON, NORTHERN WHEELER AND SOUTHERN GILLIAM
COUNTIES
SNOW THURSDAY
NORTHWEST BLUE MOUNTAINS, GRANDE RONDE VALLEY, WALLOWA COUNTY,
NORTHERN BLUE MOUNTAINS OF OREGON, SOUTHERN BLUE MOUNTAINS OF
OREGON, JOHN DAY BASIN, OCHOCO-JOHN DAY HIGHLANDS
FREEZING RAIN THURSDAY
FOOTHILLS OF THE BLUE MOUNTAINS OF WASHINGTON, FOOTHILLS OF
THE BLUE MOUNTAINS OF OREGON
WINTER MIX FRIDAY
EAST SLOPES OF THE CENTRAL CASCADES OF WASHINGTON, EAST SLOPES
OF THE SOUTHERN CASCADES OF WASHINGTON
SNOW FRIDAY
NORTHWEST BLUE MOUNTAINS, NORTHERN BLUE MOUNTAINS OF OREGON,
SOUTHERN BLUE MOUNTAINS OF OREGON
A STRONG PACIFIC WEATHER SYSTEM WILL MOVE INTO THE REGION THURSDAY
MORNING AND CONTINUE THROUGH THURSDAY NIGHT INTO NEW YEARS DAY. THIS
SYSTEM WILL BRING WARMER AIR WITH IT...RESULTING IN A WINTRY MIX OF
PRECIPITATION. THE FROZEN OR FREEZING PRECIPITATION WILL CHANGE OVER
TO ALL RAIN IN LOWER ELEVATIONS BY EARLY NEW YEARS DAY. WINTER
STORM WARNINGS HAVE BEEN ISSUED FOR THE EAST SLOPES OF THE SOUTHERN
WASHINGTON CASCADES...THE COLUMBIA RIVER GORGE...NORTH CENTRAL
OREGON...CENTRAL OREGON...LOWER COLUMBIA BASIN...YAKIMA VALLEY...AND
KITTITAS VALLEY. HEAVY SNOW ACCUMULATIONS WITH SOME ICE
ACCUMULATIONS ARE LIKELY THESE AREAS. THE HEAVIEST ICE ACCUMULATION
WILL BE IN THE COLUMBIA RIVER GORGE WITH ONE QUARTER TO ONE HALF
INCH POSSIBLE. IN THE FOOTHILLS OF THE BLUE MOUNTAINS FREEZING RAIN
WITH ICE ACCUMULATION LESS THAN ONE QUARTER INCH IS EXPECTED. OTHER
AREAS WILL RECEIVE ADVISORY SNOW AMOUNTS. PRECIPITATION WILL
DECREASE TO SHOWERS IN MOST AREAS BY 10 PM THURSDAY. TERRAIN EFFECTS
WILL KEEP LIKELY SNOW INTO FRIDAY IN THE BLUES AND EAST SLOPES OF
THE WASHINGTON CASCADES. PLEASE REFER TO PDXWSWPDT FOR MORE DETAILS.
AN ACTIVE WET BUT WARMER WEATHER PATTERN WILL THEN PERSIST THROUGH
THE REST OF THE WEEKEND INTO NEXT WEEK WITH ONE PACIFIC WEATHER
SYSTEM AFTER ANOTHER CROSSING THE REGION THROUGH A WEAK RIDGING
PATTERN.
.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION WILL BE LIKELY.
WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.
GRAPHICAL FORECASTS OF WEATHER HAZARDS OUT TO SEVEN DAYS
ARE DISPLAYED ON THE WORLD WIDE WEB AT:
WWW.WRH.NOAA.GOV/PDT/CURRENTHAZARDS/HWO.HTML
