HAZARDOUS WEATHER OUTLOOK Issue Date: 444 AM PST SAT DEC 26 2009 Expiration: 445 AM PST SUN DEC 27 2009 Expires:200912271245;;
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HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PORTLAND OR
444 AM PST SAT DEC 26 2009
ORZ001>004-010>014-WAZ019>021-040-271245-
NORTH OREGON COAST-CENTRAL OREGON COAST-
COAST RANGE OF NORTHWEST OREGON-
CENTRAL COAST RANGE OF WESTERN OREGON-
NORTHERN OREGON CASCADE FOOTHILLS-NORTHERN OREGON CASCADES-
CASCADE FOOTHILLS IN LANE COUNTY-CASCADES IN LANE COUNTY-
UPPER HOOD RIVER VALLEY-SOUTH WASHINGTON CASCADES-WILLAPA HILLS-
SOUTH WASHINGTON COAST-SOUTH WASHINGTON CASCADE FOOTHILLS-
444 AM PST SAT DEC 26 2009
THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHWEST
OREGON AND SOUTHWEST WASHINGTON.
.DAY ONE...TODAY AND TONIGHT
NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.
.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY
NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.
.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION WILL NOT BE NEEDED.
$$ SPECIAL WEATHER STATEMENT Issue Date: 354 AM PST SAT DEC 26 2009 Expiration: 315 PM PST SAT DEC 26 2009 ...POTENTIAL FOR LIGHT FREEZING RAIN SUNDAY MORNING FOR THE
INTERIOR LOWLANDS OF NORTHWEST OREGON AND SOUTHWEST WASHINGTON...
A WEAKENING PACIFIC FRONT WILL APPROACH FROM THE SOUTHWEST TODAY
AND TONIGHT...AND SLOWLY MOVE ACROSS NORTHWEST OREGON AND
SOUTHWEST WASHINGTON ON SUNDAY. AS IT DOES THE FRONT WILL
CONTINUE TO WEAKEN...DECREASING CHANCES FOR PRECIPITATION.
HOWEVER ANY PRECIPITATION FALLING INTO THE COLD AIR TRAPPED IN THE
WILLAMETTE VALLEY AND LOWLANDS OF SOUTHWEST WASHINGTON AND THE
COLUMBIA GORGE MAY BE AS FREEZING RAIN.
AT THIS TIME THE PERIOD OF CONCERN IS SUNDAY MORNING. THE SOUTH
WILLAMETTE VALLEY STANDS THE BEST CHANCE TO RECEIVE SOME LIGHT
FREEZING RAIN. CHANCES FOR FREEZING RAIN ARE LOWER TO THE NORTH AS
THOSE AREAS MAY WARM UP BY THE TIME THE RAIN ARRIVES. ANY
ACCUMULATION IS EXPECTED TO BE SPOTTY AND LIGHT. THE MAIN IMPACT
WILL BE SOME SLIPPERY ROADWAYS AND WALKWAYS SUNDAY MORNING.
THE COLUMBIA GORGE WEST OF ABOUT CASCADE LOCKS MAY RECEIVE SOME
FREEZING RAIN INTO THE AFTERNOON AS POCKETS OF FREEZING AIR LINGER
IN THAT AREA...WHILE NEAR HOOD RIVER ANY PRECIPITATION WILL LIKELY
BE AS SNOW.
$$ AIR STAGNATION ADVISORY Issue Date: 336 PM PST WED DEC 23 2009 Expiration: 600 PM PST SAT DEC 26 2009 ...AIR STAGNATION ADVISORY IN EFFECT UNTIL 6 PM PST SATURDAY FOR
THE CENTRAL AND SOUTHERN WILLAMETTE VALLEY...
THE NATIONAL WEATHER SERVICE IN PORTLAND HAS ISSUED AN AIR
STAGNATION ADVISORY...WHICH IS IN EFFECT UNTIL 6 PM PST SATURDAY.
OFFSHORE FLOW OVER THE REGION WILL STRENGTHEN OVERNIGHT AND
CONTINUE FOR THE REST OF THE WEEK INTO THE COMING WEEKEND.
HOWEVER...STRONG LOW LEVEL INVERSIONS WILL KEEP AREAS BELOW 1500
FEET FROM MIXING WELL. THIS WILL LEAD TO AIR QUALITY THAT WILL
GRADUALLY BECOME MORE POOR WITH TIME.
* AREAS AFFECTED...THE WIND SHELTERED LOWLANDS OF THE CENTRAL AND
SOUTHERN WILLAMETTE VALLEY.
* TIMING...NOW THROUGH SATURDAY.
* AIR QUALITY...EXPECT SLOWLY DEGRADING AIR QUALITY.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
AN AIR STAGNATION ADVISORY IS ISSUED WHEN LOCALLY ESTABLISHED
CRITICAL VALUES OF TRANSPORT WINDS...MIXING HEIGHT...AND
VENTILATION ARE EXPECTED TO PERSIST FOR AT LEAST 72 HOURS. THIS
PRODUCT WILL BE UPDATED AT LEAST EVERY 24 HOURS WHEN CONDITIONS
EXIST OR ARE EXPECTED TO CONTINUE.
$$
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