AIR STAGNATION ADVISORY
Warning Issue Date: 948 AM 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.
$$
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