Uncertainty remains in surface impacts from transport of wildfire smoke from out-of-state fires

 Upper level winds continue to support expectations that smoke from fires in the northwestern U.S. and Canada will move into Colorado on Sunday and into next week. However, how much of that smoke will be drawn to  the surface remains unclear. Model trends show that the greatest concentrations of smoke aloft will shift from northwestern Colorado toward northern and eastern portions of the state, possibly including the Front Range. Yet a cooler airmass is also on the way, which will bring clouds and showers to the area, and may limit much of the mixing of smoke down to the surface.

Model forecasts from the HRRR-Smoke model at 20-21 UTC (2-3pm MDT) on Sunday, July 21, 2024 show ample amounts of smoke aloft (upper image), with only pockets of light to moderate smoke reaching the surface (lower image) in northeastern Colorado (images courtesy of NOAA-NCEP).

Observations of smoke concentrations have generally agreed with model projections, so currently concerns for significant public health impacts remain minimal, however conditions may change rapidly in areas where vertical mixing enables smoke to reach the surface.

Warmer and drier conditions on Monday, with less cloud cover, may also change the vertical distribution of smoke, and may increase concerns for air quality.

We will continue to monitor this situation as it evolves, and will continue with updates and expectations as impacts become more clear. Those who are sensitive to exposure to smoke (fine particulate matter) should be prepared to undertake health precautions if conditions in your area degrade.