textproduct: Missoula

DISCUSSION

KEY MESSAGES:

- Cold wet conditions today and a winter storm for the front range and southwest Montana.

- A quick rebound expected with warm temperatures again by late week.

A cold front is moving across the region this morning, and by this evening the snow levels will be low enough for snow reach many valleys in west central, northwest, and southwest Montana. Northeasterly flow along the Continental Divide will be enhanced by the terrain allowing much higher snow rates there. Snow amounts at Rogers, MacDonald, and Homestake passes may exceed 4-6 inches by Monday morning. To complicate things, it has recently been very warm and the ground is still holding some of that heat. So when it does start snowing, most of it will melt at first, at least on paved surfaces. But after the sun goes down, or where the snow rates are high enough, the snow will eventually overcome that. At first paved surfaces will be wet, then slushy, and over some passes it will be snow on top of a slushy base. Taken along with the winds, these conditions are perfect for hypothermia, so if you're in the back-country, be prepared wet, snowy, cold, and windy conditions.

High resolution models are also showing the potential for east wind gusts over 40 mph on the southeast end of Flathead Lake. This pattern has been known to occur before, but models usually under forecast the winds or miss it completely, so its very interesting to see this. Between that effect and the gap winds through Bad Rock Canyon, a wind advisory has been issued this evening through Sunday morning for portions of Flathead and Lake counties in Montana.

Sunday or Monday will be the coldest day, but hard freezes are expected in the valleys of western Montana through mid-week next week.

In the long term, models show a ridge rebounding quickly next week. By the end of the week, afternoon high temperatures are expected to be in the 60s in western Montana and in the 70s at the lower elevations of central Idaho.

AVIATION

A winter storm is coming to the region today. Snow is expected in the mountains and at terminal KBTM this afternoon and will start to accumulate by this evening, and that area is covered by a winter storm warning starting this evening at 11/00Z and lasting through 12/12Z. Other area terminals are only expected to pick up light rain or non-accumulating snow. Recent warm temperatures have kept the ground warm which will prevent snow accumulation under light snow conditions, except at higher elevations and heavier snow rates like are expected at KBTM.

MSO WATCHES/WARNINGS/ADVISORIES

MT...Winter Weather Advisory from 6 PM this evening to 6 AM MDT Monday for Bitterroot/Sapphire Mountains...Potomac/Seeley Lake Region...West Glacier Region.

Wind Advisory from 6 PM this evening to 6 AM MDT Sunday for Flathead/Mission Valleys.

Winter Storm Warning from 6 PM this evening to 6 AM MDT Monday for Butte/Blackfoot Region.

ID...None.