Wildfire Smoke Returns to Maryland

Maryland News (7/17/2023) – Canadian wildfire smoke from British Columbia and Alberta has moved into Maryland and outside of thunderstorm activity, will persist into Tuesday. Smoke concentrations through midday Tuesday will be high enough to warrant an Unhealthy for Sensitive Groups (USG; orange) forecast for much of the state.

The greatest smoke concentrations will begin to depart the area Tuesday, and cancellation of USG air quality alerts due to smoke may be considered around midday. Still, ozone concerns will persist. Thunderstorms late in the afternoon on Tuesday will help to clean the air, from west to east.

However, ozone development east of DC may climb high enough, fast enough before this storm activity can clean the air, allowing ozone to reach the threshold of USG in eastern DC suburbs. Afternoon or evening storms will effectively end the air quality alerts there for the day. Farther northeast in Maryland, ozone will have longer to develop before the interference of storms, leading to USG ozone concentrations around and northeast of Baltimore. A weak front may then stall across the area Wednesday with more humid and hazy conditions to the south, and more chances for sun to the north.

As a result, high ozone values may exist to the north, where USG ozone is again possible in northeastern Maryland. Chances for more widespread convective activity on Thursday should help to clean out the region of any residual smoke and other pollution, resulting in upper Good to low-Moderate AQI for the region.

Original article by Maryland Department of the Environment