209 PM PST Wed Dec 11 2013
... Air stagnation advisory remains in effect until noon PST
An air stagnation advisory remains in effect until noon PST
* Synopsis: a very strong temperature inversion will persist
through Thursday morning. This will trap pollutants and lead
to air quality problems. A frontal system is expected to mix
out the inversion and clear the air Thursday afternoon.
* Locations include: Beatty... Bly... Chemult... Crescent...
Gilchrist... Sprague River... Lakeview... Grants Pass... Cave
Junction... Medford... Ashland... Altamont... Klamath Falls.
* Impacts: increasing pollution will cause air quality to
deteriorate. These conditions may make breathing more
difficult for those with health conditions. People sensitive
to air quality may wish to remain indoors.
* For a detailed view of the hazard area... visit
An air stagnation advisory indicates that due to limited movement
of an air mass across the advisory area... pollution will
... Possible freezing rain Thursday and Thursday night...
A cold front will bring the chance for precipitation to the area
Thursday through Thursday night, and with cold air trapped in the
valleys, there is a potential for freezing rain.
The freezing rain threat will begin Thursday afternoon in the
Umpqua basin and then progress south through the rogue and
Illinois valleys and to areas south and east through the evening.
Some of this rain may freeze when it hits the ground because of
the snow cover and sub-freezing temperatures experienced over the
past several days.
How quickly the cold air mixes out of the valleys will determine
how much freezing rain occurs, and overall confidence is low.
This is due to some warming in the forecast, some mixing of the
surface air as the front moves through, and the overall rarity of
freezing rain in this region.
If freezing rain occurs, ice accumulations are expected to be
minimal and anything that does accumulate should melt by Friday
afternoon. However, significant driving hazards are possible even
with light ice accumulation. Check the latest Oregon and northern
California Road conditions. As always, be sure to check the NWS
Medford homepage for updates!