Continued pattern of heavy smoke followed by clearing in Central Idaho Mountains all weekend

Air quality forecasts for today are in the Good to Unhealthy for Sensitive Groups Category.

A quasi-stationary upper-level low pressure system off the Oregon coast will continue to compete with the 4-Corners High to steer south-southwest winds and monsoon moisture into Idaho. This will bring continued hot conditions with a chance for showers to much of the state with a slight chance of showers over the Snake River Plain and the Panhandle.  Surface winds will be from the southeast to southwest at 5-10 mph with gusts between 15-25 mph. Meanwhile, Gusts will be 35 mph+ near any of the stronger storms.  

This weekend, the upper-level low pressure system finally weakens and tracks eastward over the ridge. This will shift monsoon moisture east and so a chance for showers remains over eastern Idaho. On Sunday, the mean flow will become west-southwest, limiting the monsoon impacts to the Southeast and Eastern Highlands with the rest of the state expected to stay dry.  Winds this weekend will be from the west with northwest to southwest flow depending on local topography. Surface wind speeds will be from 5-10 mph with stronger winds between Spokane and Coeur d’Alene. On Monday, a ridge pattern will develop ushering in hot temperatures and dry conditions. Surface winds will be light and variable in direction.

Smoke will continue to affect the Central Idaho Mountains the greatest this afternoon.  Decreased fire activity will limit smoke production this morning; however, conditions could ramp up this afternoon near any thunderstorms and gusty winds, bringing periods of deteriorated air quality to the Salmon area this afternoon. This pattern will repeat again tomorrow and Sunday with periods of heavy smoke followed by clearing. Additionally, the general southerly flow will push smoke north and create hazy skies over central and north Idaho. The shift in flow on Sunday into Monday will likely bring a return of drainage smoke to the Upper Snake River Plain in the morning on Monday before clearing around lunch time.

HRRR-Smoke Vertically Integrated Smoke initialized at 12Z (06am MDT) and valid at 4pm MDT 08/12 shows limited smoke aloft over much of Idaho with local pockets of increased concentrations near active fires.