Air Stagnation Advisory:

Issued at: 11:40 am PST on November 26, 2015, expires at: 12:00 PM PST on November 30, 2015
  • ...Air stagnation advisory remains in effect from 9 PM this evening to noon PST Monday...
  • air quality...poor ventilation will result in a build up of pollutants near the surface. Mountain valleys will be especially susceptible to stagnant air and pollution build up. Light northeasterly winds across the basin will also tend to push pollutants up against the east slopes of the northern Cascades between Thursday and Saturday. These winds will become calm by Sunday with a greater risk of pollutant build up over much of the region by this time.
  • Timing...Thursday night through Monday morning.
  • Impacts...prolonged periods of stagnant air can hold fine particulates close to the ground and degrade air quality. Precautionary/preparedness actions... An air stagnation advisory indicates that due to limited movement of an air mass across the advisory area...pollution has the potential to increase to dangerous levels. Persons with respiratory illness should follow their physicians advice for dealing with high levels of air pollution. During periods of stagnant air...state air quality agencies highly recommended that no outdoor burning occur and that residential wood burning devices be limited as much as possible. According to state air quality agencies...prolonged periods of stagnant air can hold pollutants close to the ground...where people live and breathe.

First Alert 48 Hour Forecast

High pressure will dominate western Montana's weather through Saturday.  That means frigid nights and sunny, cold days through the early weekend.  Lows dropping below zero area wide Thursday night with single digits above and  below zero Friday night.  Highs during the days in the upper 10s and 20s. Morning freezing fog will be possible Saturday with some areas having it hang around a good part of the day.

Lake effect snow flurries will possible on the southeast side of Flathead Lake with low clouds possibly hovering over the Mission Valley.

Increasing cloud cover will prelude a round of light snow moving through Southwest Montana and possibly as far north as Missoula sometime between Saturday night and late Sunday.

Milder weather will be back into the forecast next week with skies remaining mostly dry.

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First Alert Meteorologists

mark heyka

Mark Heyka

Mark Heyka received a B.A. in broadcast journalism from Washburn University in Topeka, Kansas.

brooke foster

Brooke Foster

Brooke Foster joined the NBC Montana team in March of 2006.

Matt Gray

Matt Gray

Matt joined the NBC Montana weather team in July 2013 and fell in love with the Montana lifestyle.