AIR STAGNATION ADVISORY
Warning Issue Date: 349 PM PST THU DEC 24 2009
...AIR STAGNATION ADVISORY REMAINS IN EFFECT UNTIL 4 PM PST
SATURDAY...
AN AIR STAGNATION ADVISORY REMAINS IN EFFECT UNTIL 4 PM PST
SATURDAY.
* STRENGTHENING HIGH PRESSURE OVER THE REGION HAS DEVELOPED AN
INVERSION OVER THE VALLEYS OF SOUTHERN OREGON.
* THIS INVERSION WILL STRENGTHEN TONIGHT AND IS LIKELY TO
PERSIST THROUGH AT LEAST SATURDAY.
* COLD AND STABLE AIR WILL REMAIN TRAPPED IN THE VALLEYS.
THEREFORE TEMPERATURES WILL BE WARMER IN THE MOUNTAINS THAN IN
THE VALLEYS THROUGH SATURDAY.
* POLLUTANTS SUCH AS SMOKE AND OTHER AIRBORNE PARTICULATES WILL
BECOME TRAPPED IN THE VALLEYS AND...AT TIMES...AT MID
ELEVATIONS. THIS WILL CREATE THE POTENTIAL FOR DIMINISHING AIR
QUALITY.
* LOCALLY DENSE FREEZING FOG WILL FORM IN MANY VALLEYS SUCH AS
THE ROGUE...UMPQUA...AND ILLINOIS VALLEYS. THIS WILL CREATE
THE POTENTIAL FOR SLIPPERY ROADWAYS DUE TO FROST FORMATION.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
AN AIR STAGNATION ADVISORY INDICATES THAT DUE TO LIMITED MOVEMENT
OF AN AIRMASS ACROSS THE ADVISORY AREA...POLLUTION WILL INCREASE.
$$
BTL/MW
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