Similar weather to this past week is expected to continue through the weekend. Due to light transport and surface winds, expect smoke to lift in the afternoon for brief reductions in concentrations before settling back down in the evening when concentrations will again build to elevated levels. Wildfires in Canada, Oregon, Idaho, and Montana will continue to supply smoke to the air. Air quality is forecast to continue in the Moderate to Unhealthy air quality category across the state today. For more detail and specifics about critical areas please read the Smoke Outlook below.
Updated 10am MDT Thursday, August 10, 2017
Valid through Noon MDT Friday, August 11, 2017
Air quality is forecast to continue in the Moderate to Unhealthy air quality category across the state today. Monitors are currently reading in the Moderate to Unhealthy Category over much of Idaho with the Camas Prairie, Weippe Prairie and parts of the Clearwater Drainage showing hourly readings in the Unhealthy Category. A clear dichotomy between northern and southern Idaho exists with north Idaho experiencing 24 hour AQI values in the Unhealthy for Sensitive Groups and Unhealthy categories while south Idaho experienced ubiquitous Moderate readings with the exception of McCall, which saw levels reach the Unhealthy for Sensitive Groups yesterday.
Today will see similar weather to this past week due to an upper level blocking pattern off the Pacific Coast. Small amounts of moisture will be present over portions of the southern Highlands, which will allow for a slight chance of afternoon and evening thunderstorms over the area. Elsewhere, surface winds will be light and generally from the northwest to east-southeast at 5-10 mph. Northern Idaho will see 2-8 mph with northeast to northwest winds. Skies will be mostly sunny to sunny; however expect widespread smoke to limit visibility and solar radiation across northern Idaho. Mixing heights will range from 9,000-13,000 feet AGL across all of Idaho today. Transport winds will be from the northeast to northwest at 5-10 mph. Due to the light transport and surface winds, expect smoke to lift in the afternoon before settling back down in the evening.
Smoke impacts are expected to be greater in the morning prior to the inversion lift with higher readings across much of the Weippe and Camas Prairies and within the Clearwater drainage. Expect similar conditions through this weekend with consistent heavy impacts over the Clearwater drainage to Lewiston to the west and intermittent periods of heavy impacts from the Canadian border and south to the St. Joe drainage. Consistent northwest winds will bring smoke from regional fires into the northern Panhandle and south to the Salmon River. South of the Salmon River, expect light impacts and hazy skies south to the Snake River Plain except for the North Fork Payette drainage where smoke is expected to be heavier. Within the Snake River Plain, brief periods of haze should be expected. Drainage smoke via the Payette and Boise-Mores drainages will bring surface smoke to the Treasure Valley, early Friday morning. Salmon should expect to see smoke early Friday morning as well.