Cottonwood Butte Snow Report

098 FXUS65 KMSO 062044 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 244 PM MDT Thu Aug 6 2026 .DISCUSSION... KEY MESSAGES: - Warming trend through the rest of the week. - Wildfire smoke will continue to impact the region until further notice. - Ridge of high pressure flattens heading into the weekend. Near- critical to critical fire weather expected due to hot, dry and breezy conditions. A building upper-level ridge will maintain hot, dry, and stable conditions across western Montana and north-central Idaho. Temperatures will warm significantly Friday and Saturday, with lower elevations reaching the 90s and localized spots exceeding 100 degrees. As the ridge flattens into zonal flow this weekend, afternoon surface winds will increase. Hot temperatures, low relative humidity, gusty winds, and critically dry fuels will maintain near-critical to critical fire weather conditions, peaking Friday into Saturday. The main focus for the most critical conditions is expected across southwest and west-central Montana along with the Palouse and Hells Canyon region of north- central Idaho with Fire Weather Watches issued. Wildfire smoke remains a key forecast challenge for air quality and visibility. Strong radiational cooling under smoky skies will yield sharp nocturnal valley inversions each morning, trapping surface particulates. While daytime boundary layer mixing will temporarily disperse valley smoke each afternoon, increased ventilation will also invigorate fire activity and generate thicker plumes aloft. High-resolution smoke models project surface smoke peaking early this afternoon before modestly improving by early evening. Monsoonal moisture tracking along the ridge periphery introduces a slight chance for isolated high-based convection Friday afternoon through the weekend, primarily across southwest Montana. An anomalously dry sub-cloud layer will pose a risk for dry lightning ignitions and erratic microburst gusts of 40 to 55 mph. Forecast confidence is low to moderate but trending upward regarding moisture returning mid/late next week. At this point, the moisture doesn`t appear deep or organized enough for widespread rainfall. A substantial synoptic shift such as a deep Pacific Northwest trough will be required to suppress fire activity and clear smoke. Ensemble guidance shows a 20 to 30% chance of this trough arriving by mid to late next week. && .AVIATION...Widespread wildfire smoke remains the primary aviation hazard over the next 24 hours. Sharp nocturnal inversions and strong radiational cooling will trap surface smoke in valley basins overnight through mid-morning, maintaining periods of MVFR to localized IFR visibilities (along with locally reduced ceilings). Daytime heating will promote boundary layer mixing and yield modest surface visibility improvements by afternoon; however, enhanced ventilation will also invigorate regional fire activity, generating thicker smoke plumes aloft and impacting slant-range visibility. High density altitude will be a prominent operational concern as afternoon temperatures reach the 90s and low 100s. Surface winds will remain light and terrain- driven with a westerly gradient by Friday afternoon. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...Fire Weather Watch from Friday afternoon through Saturday evening for Bitterroot...Deerlodge/West Beaverhead...East Beaverhead...East Lolo. Fire Weather Watch from Saturday afternoon through Saturday evening for Flathead Reservation...West Lolo. Red Flag Warning until 9 PM MDT this evening for Deerlodge/West Beaverhead...East Beaverhead. ID...Fire Weather Watch from Friday morning through Saturday evening for Palouse/Hells Canyon. && $$