HAZARDOUS WEATHER OUTLOOK
Issue Date: 552 AM PST FRI DEC 25 2009
Expiration: 600 AM PST SAT DEC 26 2009

Expires:200912261400;;
FLUS46 KPQR 251352
HWOPQR
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PORTLAND OR
552 AM PST FRI DEC 25 2009
ORZ007-008-WAZ022-039-261400-
CENTRAL WILLAMETTE VALLEY-SOUTH WILLAMETTE VALLEY-I-
5 CORRIDOR IN COWLITZ COUNTY-GREATER VANCOUVER AREA-
552 AM PST FRI DEC 25 2009
THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHWEST
OREGON AND SOUTHWEST WASHINGTON.
.DAY ONE...TODAY AND TONIGHT
AIR STAGNATION ADVISORY IN EFFECT 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...SATURDAY THROUGH THURSDAY
AIR STAGNATION ADVISORY REMAINS IN EFFECT THROUGH 6 PM SATURDAY 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.
.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION WILL NOT BE NEEDED.
$$

AIR STAGNATION ADVISORY
Issue Date: 242 PM PST THU DEC 24 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 STRENGTHEN OVERNIGHT AND
CONTINUE INTO SATURDAY. HOWEVER...STRONG LOW LEVEL INVERSIONS
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.
&&
$$