Air stagnation across the region through early next week

Pattern change by late next week
Posted at 2:23 PM, Dec 02, 2020
and last updated 2020-12-02 16:23:53-05

BOZEMAN – High-pressure is dominating our weather pattern right now and should be locked into place through early next week.

Overall, this will keep our local and regional weather pattern quiet with sinking stable air associated with the massive ridge.

There are side effects with this type of pattern during the colder winter months. Sinking stable air produces stronger valley inversions which traps cold air at the surface along with pollutants.

There are widespread “Air Stagnation Advisories” up across the Pacific NW, Idaho and far western Montana.


A buildup of pollutants will bring deteriorating air quality conditions. Those with breathing problems should try and limit outdoor exposure as much as possible in the advisory areas.

Travel weather should be fantastic through early next week with this blocking pattern and now is the time to finish your holiday decorating this weekend.

Looking ahead the Climate Prediction Center 8 to 14 day outlook from December 10 to the 16th shows a possible pattern change to impact Montana beginning late next week.

As the current ridge pattern breaks down look for a stronger northerly flow to develop and that should produce colder than normal temperatures especially east of the divide for Montana and there could be slightly above normal snowfall as well.