Overnight Monday into this morning, an atmospheric river originating over the Pacific Northwest pushed into the Northern Rockies. The atmospheric river will continue to move through that area today mainly dropping precipitation in the form of rainfall. Rainfall accumulation may exceed 1 inch for mountain ranges across northwest Montana and the northern Clearwater Mountains in Idaho. That relatively warm subtropical airmass will raise snow levels to the 5000 to 6000 feet range through midday. After that, a colder Pacific storm system will cut off the subtropical moisture and introduce cold air aloft. This cold air aloft will combine with a powerful jet stream to decrease stability across the Northern Rockies, resulting in showers or thunderstorms that may contain sudden rain, snow, graupel, small hail, and/or wind gusts over 40 mph. The National Weather Service has issued a HIGH WIND WARNING for areas including the Northern Rocky Mountain Front, Eastern Glacier, Eastern Pondera, Southern Rocky Mountain Front, Marias Pass, Bynum, Brady, Choteau, Browning, Heart Butte, Logan Pass, Augusta, Cut Bank, and Conrad. Sudden wind gusts combined with saturated soils associated with recent melting of low elevation snowpack may result in tree damage across northwest Montana or low elevations of western Clearwater or Idaho counties, Idaho. As I mentioned thunderstorms, it's important to note that large risk of lightning extends across northwest Montana and north-central Idaho this afternoon. Even in the absence of a shower or thunderstorm cell, wind gusts of 20 to 30 mph will be common across the Northern Rockies through sunset this evening. It is possible that Helena may see a few snow showers, rain, or a mix of both throughout the day today. However, due to downsloping winds, I don't believe that Great Falls has much of a chance to see precipitation today. As large areas of clouds dissapate and clear Wednesday, rapid atmospheric heating will begin. Due to this, most of Montana will have widespread atmopheric instability. This will lead to thunderstorms and and bands of rain or snow. With the atmospheric instability, I like the chances to hear our first thunder of the year on Wednesday. As a high pressure system settles over the state Thursday, many areas will see warmer temperatures nearing the mid to upper 50's, as well as a healthy dose of sunshine on ST. Patrick's Day. There is a weak system that will move into Montana on Friday. Though it's too early to say for sure, a large storm that appears to be going south of us, might end up tracking a bit further north, which would spray us with wet snow on Sunday. Have a great day! Thank you for trusting #StormTrackerWeather and as always:
A cloudy day is no match for a sunny disposition!
Be nice to each other.
- Trey Tonnessen -