Smoke on the Front Range coming from several sources this week

 While a lot of attention on smoke in northern Colorado is focused on the Alexander Mountain fire (and rightfully so), smoke transport from other fires in the western U.S. will also play a role in air quality conditions as the week progresses.

A weak cool front will move through the area on Tuesday night, and is expected to create surface winds out of the north on Wednesday. This will push smoke from the Alexander Mountain fire into areas further south of those that are already affected, and will also bring smoke from fires in upwind states into the mix. On Tuesday morning air quality impacts from the out-of-state fires are already seen across northern and western Wyoming (as well as other states), and with winds shifting to move things toward the south, we expect to see some of that smoke move into Colorado overnight Tuesday and into Wednesday morning.

Map of  smoke (fine particulates) impact on air quality in courtesy of PurpleAir.

By 9 am MDT (15 UTC) on Wednesday the HRRR-Smoke model shows smoke produced locally moving southward from Loveland, CO along the Front Range, reaching at least as far south as the Denver Metro area. Additionally, the smoke currently to our north will move into northern and central Colorado, with the highest concentrations hugging the eastern slope of the Rockies, worsening air quality conditions along the Front Range. This means that in addition to smoke being seen in Loveland and along Highway 34, increased particulate concentrations are expected in Fort Collins, Greeley, Longmont, Boulder, Denver, and surrounding areas.

The impact from out-of-state transport of smoke will also be seen in areas of northern/northwestern Colorado, and on the eastern plains. Though concentrations are expected to be a bit less than will be seen along the Front Range, light to moderate concentrations of smoke are expected across large areas of the state, with potential to affect many outdoor recreation areas and outdoor workers in these areas. We encourage everyone to remain aware and cautious in regard to heavy physical exertion, especially when outdoors, due to the heat and air quality that will affect Colorado in the coming days.

With these expectations in mind, along with temperatures in the mid-to-upper 90's and limited cloud cover, air quality concerns for health impacts due to exposure to both fine particulates (smoke) and ozone will be heightened this week. CDPHE/APCD will keep a close eye on conditions as all of this develops, however it is likely that the Ozone Action Day alert that is currently in effect for the northern Front Range region will be upgraded to an Action Day for Multiple Pollutants as particulate pollution spreads to wider areas.