AIR STAGNATION ADVISORY
Warning Issue Date: 1010 AM PST THU DEC 24 2009
...AIR STAGNATION ADVISORY REMAINS IN EFFECT UNTIL 6 PM PST
SATURDAY FOR THE CENTRAL AND SOUTH WILLAMETTE VALLEY...
...DENSE FOG ADVISORY HAS EXPIRED...
THE DENSE FOG ADVISORY IS NO LONGER IN EFFECT. AN AIR STAGNATION
ADVISORY REMAINS IN EFFECT UNTIL 6 PM PST SATURDAY.
FOG IS THINNING A BIT THIS MORNING...AND WILL CONTINUE TO THIN
THROUGH THE DAY. HOWEVER...EXPECT LOCAL VISIBILITIES TO REMAIN
POOR AT TIMES THIS MORNING...ESPECIALLY NEAR THE WILLAMETTE RIVER.
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.
$$
|
|
|
