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Winter Air Quality Update & Forecast
Wednesday, January 16, 2019 12:56 PM

Locations and Air Quality Conditions

Current Situation Forecast
Several valley locations continue to experience MODERATE air quality this morning, as overnight inversions have still been in place. Butte and Helena both reached UNHEALTHY FOR SENSITIVE GROUPS overnight, but generally have been improving since then. Other reporting locations are experiencing GOOD air quality. The ridge of high pressure that has been in place throughout the beginning of the week finally begins to break down today, as disturbances move into the state from the southwest. Winds will gradually increase throughout the day, with increased chances of precipitation. Air quality should generally continue to improve today and remain GOOD to MODERATE, with some potential for weak inversions overnight.

Starting Thursday, a stronger disturbance from the Pacific should start making its way towards Montana, which will increase winds aloft, southwest surface winds, and chances for snow over the region. This will be favorable to air quality and help to weaken overnight inversions. By Friday and into the weekend, another high pressure ridge starts to build, which will again bring calmer and more clear conditions, and stronger overnight inversion potential. However, it appears that it will be shorter lived than the ridge we were currently under.

Air Quality Bureau
Montana Department of Environmental Quality
Phone: (406) 444-3490

A little hazy today in Helena. 

A little hazy today in Helena.
Source: DEQ

Calm valley winds forecasted for today.

Calm valley winds forecasted for today.
Source: NOAA


Real time particulate information is currently available in most of the larger urban areas from MTDEQ's Today's Air website.

Today's particulate report below compares particulate levels received from DEQ's
reporting stations with MTDEQ’s Health Effect Categories.

Locations and severity of PM 2.5 particulate values over the past 24 hours from the time above.
Health Effects Categories City
  Very Unhealthy  
  Unhealthy for Sensitive Groups  

Seeley Lake


 All other reporting locations. 

B1(x) One-hour BAM value (number of values)
B8(x) Eight-hour average BAM
B24 24 hour  average BAM value