Airshed
Management
System

Discussion: (For details on individual airsheds see table below)

A slow moving upper level low pressure system will move through the intermountain west over the weekend keeping cool conditions and high humidity with light winds. For most areas this will create POOR to MARGINAL dispersion through Sunday. Southeast ID will be the one exception with a bit more southerly wind producing GOOD to EXCELLENT dispersion on Saturday and MARGINAL to GOOD dispersion on Sunday.

Another weaker system passes over the area Monday into Tuesday keeping conditions cool and unsettled. Dispersion does begin to improve for southwest and central and eastern MT for MARGINAL to GOOD conditions but much of the rest of the region will continue POOR to MARGINAL. Later next week upper level high pressure moves into the Pacific Northwest with a cool northwest flow aloft setting up over ID/MT. This pattern is likely to support inversion formation over ID and western MT especially in areas where recent moisture supports overnight fog formation.

Dan Borsum – Northern Rockies Predictive Services Meteorologist