textproduct: Missoula

DISCUSSION

KEY MESSAGES:

- Widespread smoke continues to degrade air quality and visibility driven by regional wildfire activity.

- Elevated to near-critical fire weather continues along and south of the I-90 corridor through Monday.

- Gradual cooling trend by middle of next week as showers return to the forecast.

The Northern Rockies will remain under the influence of a dry westerly flow aloft through early next week. High pressure will remain centered across the Great Basin and Four Corners states, with low pressure systems passing to the north in Canada. This pattern will continue to bring elevated fire weather concerns due to hot, dry, and breezy conditions. The worst fire weather is expected along and east of the divide in southwest Montana, where near-critical fire weather is forecast by Monday. Future shifts will closely monitor the need for another round of Red Flag Warnings on Monday. Smoke from regional wildfires will continue to bring air quality impacts and reduced visibility for at least the next 24 hours.

A gradual moistening and slight cooling trend is expected by Tuesday next week. Then, there is modest confidence for increased precipitation chances and colder temperatures by Wednesday into Thursday. The best chances for cooler and wetter conditions remains confined to areas north and along the Canadian Border into the Flathead National Forest closer to the cold core of an incoming trough, where higher moisture availability and lifting mechanisms are expected.

AVIATION

Wildfire smoke will be the primary aviation impact during the next 24 hours. Smoke will reduce visibility into the IFR to MVFR categories through at least 09/1800Z today, with gradual improvements by this afternoon as vertical mixing improves. West-northwest surface winds are expected by mid- afternoon, with gusts of 15-25kts along the divide.