HAZARDOUS WEATHER OUTLOOK
Issue Date: 444 AM PST SAT DEC 26 2009
Expiration: 445 AM PST SUN DEC 27 2009

Expires:200912271245;;
FLUS46 KPQR 261244
HWOPQR
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PORTLAND OR
444 AM PST SAT DEC 26 2009
ORZ005>009-WAZ022-023-039-271245-
LOWER COLUMBIA-GREATER PORTLAND METRO AREA-
CENTRAL WILLAMETTE VALLEY-SOUTH WILLAMETTE VALLEY-
WESTERN COLUMBIA RIVER GORGE-I-5 CORRIDOR IN COWLITZ COUNTY-
GREATER VANCOUVER AREA-
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
AIR STAGNATION ADVISORY IN EFFECT THROUGH THIS AFTERNOON FOR
NORTHERN CLARK COUNTY...COWLITZ VALLEY...CENTRAL AND SOUTH
WILLAMETTE VALLEY. A STRONG PERSISTENT SURFACE BASED TEMPERATURE
INVERSION HAS RESULTED IN LIMITED MIXING OF THE NEAR SURFACE AIR.
THIS WILL RESULT IN SLOWLY DEGRADING AIR QUALITY.
.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY
THERE IS A SLIGHT CHANCE FOR FREEZING RAIN SUNDAY MORNING FOR THE
WILLAMETTE VALLEY...LOWER COLUMBIA...AND COLUMBIA RIVER GORGE AS
A WEAK FRONT SWINGS FROM SOUTH TO NORTH ACROSS THE AREA ON SUNDAY.
PORTIONS OF THE COLUMBIA RIVER GORGE WEST OF CASCADE LOCKS MAY
EXPERIENCE LOCAL FREEZING RAIN INTO THE AFTERNOON. ANY FREEZING
RAIN WILL BE SPOTTY AND MELT AWAY LATER IN THE DAY.
.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: 948 AM PST FRI DEC 25 2009
Expiration: 600 PM PST SAT DEC 26 2009

...AIR STAGNATION ADVISORY REMAINS IN EFFECT UNTIL 6 PM PST
SATURDAY FOR THE CENTRAL AND SOUTH WILLAMETTE VALLEY...
AN AIR STAGNATION ADVISORY REMAINS IN EFFECT UNTIL 6 PM PST
SATURDAY.
OFFSHORE FLOW OVER THE REGION WILL CONTINUE INTO SATURDAY.
HOWEVER...A STRONG LOW LEVEL INVERSION WILL KEEP AREAS BELOW 1500
TO 2000 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.
&&
$$