AIR STAGNATION ADVISORY
Warning Issue Date: 203 PM PST FRI DEC 25 2009
AIR STAGNATION ADVISORY REMAINS IN EFFECT FOR MOST THE INTERIOR
LOWLANDS OF WESTERN WASHINGTON UNTIL 10 AM PST SATURDAY...
STRONG HIGH PRESSURE ALOFT WILL PERSIST OVER THE REGION FOR THE
NEXT COUPLE OF DAYS...TRAPPING COLD AIR NEAR THE SURFACE UNDER
WARM AIR ALOFT. THE RESULTING LOW LEVEL TEMPERATURE INVERSION
ALONG WITH LIGHT SURFACE WINDS WILL ALLOW POLLUTANTS LIKE WOOD
SMOKE AND VEHICLE AND INDUSTRIAL EMISSIONS TO
ACCUMULATE...DEGRADING AIR QUALITY.
WINDS WILL PREVENT STAGNATION ALONG THE COAST...THE STRAIT OF
JUAN DE FUCA AND ALSO ACROSS THE SAN JUAN ISLANDS. THE OLYMPICS
AND CASCADES WILL ALSO BE ABOVE THE STAGNANT INVERSION LAYER.
THEREFORE THESE AREAS ARE NOT INCLUDED IN THE ADVISORY.
GAP WINDS THROUGH THE CASCADE PASSES ARE EXPECTED TO DEVELOP
FRIDAY AFTERNOON THROUGH SATURDAY. A PERIOD OF IMPROVED AIR
QUALITY IS EXPECTED NEAR THE CASCADE FOOTHILLS...EAST PUGET SOUND
LOWLANDS...AND POSSIBLY SOME OTHER AREAS FROM KING COUNTY
NORTHWARD. THE SOUTH PUGET SOUND AND SOUTHWEST INTERIOR WILL
LIKELY REMAIN STAGNATE INTO SATURDAY MORNING. CONTINUE TO MONITOR
THE LATEST FORECASTS.
CHECK WITH YOUR LOCAL AIR QUALITY AGENCY FOR POSSIBLE RESTRICTIONS
IN YOUR AREA.
$$
MERCER
WEATHER.GOV/SEATTLE
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