397 FXUS65 KMSO 271132 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 432 AM MST Wed Feb 27 2019 .DISCUSSION...Light snow is spreading across Central Idaho and Western Montana currently, this is associated with Pacific moisture being pushed up by a upper level circulation off the Washington and Oregon coast. With the southerly winds in Idaho, expect the Camas Prairie and Salmon to warm into mid 40s with even the Southern Bitterroot approaching the upper 30s. The rest of us will see mid 20s as easterly winds continues to advect cooler air across the Continental Divide. Precipitation will generally be light, with broad inch or 2 coverage. Higher terrain and mountain passes of Central Montana may see 2 to 4”. That said the Camas Prairie and Salmon will likely see a wintry mix of precipitation. Light snow will continue over night Wednesday into Thursday, a second push of moisture will affect Western Montana in the afternoon through evening commute. The possibility of periods of moderate snow should not be ruled out and roads will become slick. Highest accumulation will be Lolo Pass and Bitterroot Mountains where a total of 6 to 12” is possible. For the valleys, Missoula and I-90 east could locally see up to 4”, elsewhere a broad 1 to 3” is forecast. Once again, rain could mix in for the Camas Prairie and Lemhi County. Relatively moist northwest flow will be present over the Northern Rockies Friday through Sunday, with an embedded cold wave re- introducing more arctic air to western Montana. The Flathead Valley, Glacier Park region, and Seeley-Swan Valley appear to be most impacted by this next arctic intrusion, with the combination of light snow and gusty east/northeast winds creating blowing snow, low visibility, and hazardous snow covered roadways. Gusty east/northeast winds will develop within the typical terrain features, such as Hellgate Canyon (Missoula Valley) and Badrock Canyon (Flathead Valley). The winds will undoubtedly produce some very cold wind chill. In addition to frostbite risk for exposed skin, newborn livestock will continue to be at-risk with daytime temperatures more than 20 degrees below the seasonal average (particularly near the Continental Divide). Meanwhile, conditions will be a little showery over north central Idaho, with temperatures only slightly cooler than the seasonal average. Models depict a relatively dry pattern over the Northern Rockies Monday through Tuesday, as upper flow shifts from northerly to southwesterly. Daytime temperatures will warm a bit during this time, however still well below the seasonal for most of the region. A surge of moisture embedded within southwest flow aloft is anticipated to arrive over the Northern Rockies Wednesday and interact with a relatively cold Pacific storm system through Thursday. The net result of this interaction will be yet another round of snow, particularly across northwest Montana (however, confidence in specific location of best snow potential is low at this point). The pattern itself seems plausible, considering that it resembles the recent exceptional cold, snowy pattern over the region. && .AVIATION...Light precipitation associated with warm air overrunning will spread across the forecast area this morning. Expect higher terrain being obscured and KMSO, KBTM, and KSMN to fluctuate back and forth from IFR to MVFR conditions due to low ceilings and low visibility due to moderate showers. KMSO may experience periods of blowing snow, further degrading visibilities to near zero at times, due to east winds gusting to 20 knots before slackening off in the afternoon. Conditions will only slightly improve overnight Wednesday before another surge of moisture spreads across the area Thursday. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...None. ID...None. && $$