HAZARDOUS WEATHER OUTLOOK
Issue Date: 1025 AM PST WED DEC 30 2009
Expiration: 615 AM PST THU DEC 31 2009
THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL AND NORTHEAST OREGON
AS WELL AS SOUTH CENTRAL AND SOUTHEAST WASHINGTON.
.DAY ONE...TODAY AND 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, NORTHWEST BLUE MOUNTAINS,
EASTERN COLUMBIA RIVER GORGE OF OREGON, CENTRAL OREGON,
WALLOWA COUNTY, NORTHERN BLUE MOUNTAINS OF OREGON, OCHOCO-JOHN
DAY HIGHLANDS
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. HEAVY SNOW
ACCUMULATIONS WITH SOME ICE ACCUMULATIONS ARE LIKELY IN MANY AREAS.
A WINTER STORM WATCH HAS BEEN ISSUED FOR THE AREAS LISTED ABOVE FOR
THE POSSIBILITY OF SIGNIFICANT ACCUMULATIONS OF THE WINTRY MIX OF
PRECIPITATION. PLEASE REFER TO PDXWSWPDT FOR 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 MAY BE REQUIRED.
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
ALL LETTERS IN THE ABOVE URL ARE LOWER CASE...EXCEPT THE H IN
CURRENTHAZARDS.
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