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Winter Air Quality Update & Forecast
Wednesday, January 30, 2019 10:51 AM

Locations and Air Quality Conditions


Current Situation Forecast
Cold air and strong valley inversions are present across western Montana on Wednesday morning. The valley cold pools of air are due to a ridge of high pressure sitting over Montana. This ridge is creating light surface winds and limited vertical motion, leading to stagnant air in the valleys. Air quality in currently MODERATE in Seeley Lake, Frenchtown, Missoula, Hamilton, Helena, and Butte. Temperatures in these valleys are generally in the single digits, with ridgetop temperatures in the 20s. Up along those ridges, air movement is much better, with warmer temperatures and breezy conditions. Northwest Montana has fared better, with slightly warmer temperatures and weaker inversions. Air quality in northwest Montana is ranging between GOOD and MODERATE this morning. Unfortunately, the ridge of high pressure causing the air quality concerns in the valleys is expected to continue impacting the region through Thursday. We are also seeing more widespread cloud cover today. These clouds are inhibiting the lifting of inversions in many locations. This is because the solar radiation from the sunlight helps to erode the cold air pools and promotes lifting. Without the sunshine, these inversions are going to be stubborn to break.

Conditions will be similar on Thursday, with the cloud cover keeping the inversions in place. For areas that do manage to break the inversions on Wednesday, the cloud cover may help keep overnight temperatures from dropping too far. For most valleys, however, lows in the single digits and teens are likely once again. Air quality on Thursday will likely remain MODERATE around western Montana, especially in Missoula, Hamilton, Helena, and Butte. Some of those areas may see hourly levels reach UNHEALTHY FOR SENSITIVE GROUPS at times, especially Thursday morning.

We should finally start to see improvement on Friday as warmer air attempts to push into the region. Most valleys should start to see improved air quality by Friday afternoon. There is a chance that particularly strong inversions may linger into Saturday. Beginning Saturday and lasting into next week, unsettled weather with widespread snow shows is expected as a trough of low pressure moves into the area. Air quality should improve for all locations for the weekend and into early next week.

Air Quality Bureau
Montana Department of Environmental Quality
Phone: (406) 444-3490
Email: DEQMTSmoke@mt.gov




An inversion over the Helena Valley is creating moderate air quality today.  

An inversion over the Helena Valley is creating moderate air quality today.
Source: MT DEQ

 
Strong winds along ridge tops are unlikely to make it down into the valleys this afternoon.

Strong winds along ridge tops are unlikely to make it down into the valleys this afternoon.
Source: Weather Underground

Dispersion is expected to be poor during the day tomorrow in the valleys.

Dispersion is expected to be poor during the day tomorrow in the valleys.

Source: University of Washington 




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
  Hazardous  
  Very Unhealthy  
  Unhealthy  
  Unhealthy for Sensitive Groups  
  Moderate

 Butte
Frenchtown
Hamilton
Helena
Libby
Missoula
Seeley Lake
 

  Good

 All other reporting stations. 

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