Smoke Outlook

Air quality is forecast to continue to remain in the Unhealthy for Sensitive Groups to Hazardous category for the 24 hour AQI across the state today; however hourly readings may be much higher at times.  Most recent monitor observations are currently reading in the Unhealthy for Sensitive Groups to Hazardous level for an hourly reading.  Yesterday saw levels that reached the Hazardous category across central Idaho and the Panhandle while southern Idaho experienced widespread Unhealthy for Sensitive Groups to Very Unhealthy conditions for the 24hr AQI.   Areas currently being impacted most severely are across the Panhandle and south to the Clearwater drainages where conditions are in the Unhealthy to Hazardous category and are forecast to be in the Hazardous for a 24hr AQI at some locations. Dense smoke is present both aloft and at the surface and regional weather conditions are unlikely to change for the next 24-36 hours.

The upper level ridge will continue to sit over all of Idaho and drive light, easterly winds with a warm mid-layer that will cap mixing and vertical movement of the smoke.  A mid-level high pressure system will settle over the intersection of WA/ID/OR today and provide a northerly to northeasterly steering component over Idaho at the mid-levels.  Surface winds will be from the northeast to northwest at 5-10 mph.  Skies will be sunny when not obscured by smoke.  Mixing heights will range from 2,000-5,000 feet AGL across all of Idaho today.  Transport winds will be from the northeast to northwest at 5-10 mph.  Temperatures will remain high, although dense smoke coverage will limit maximum temperatures.    Beginning Thursday afternoon and early Friday morning, the upper level ridge will weaken as a disturbance approaches from the south.  This low pressure system will become cut off and settle over California and provide a southwesterly wind to southern Idaho by Saturday and persist through the weekend which may allow some clearing for southern Idaho.  Next week, a zonal flow pattern will bring a westerly to northwesterly wind pattern and potentially bring smoke back into the Idaho airsheds

 

The easterly winds at the surface are expected to persist through at least Wednesday with the light easterly winds continuing through Thursday over northern Idaho.  Expect substantial and continued deterioration of the air quality across the entire state with the heaviest impacts continuing over the Idaho Panhandle and Central Idaho.  Beginning late Thursday afternoon, conditions may allow for limited improvement over south Idaho. These conditions are likely to deteriorate once more into the evening hours and early Friday morning.  Deteriorating conditions are expected to persist over central Idaho and the Panhandle through Friday.