textproduct: Missoula

DISCUSSION

KEY MESSAGES:

- Winter Weather Advisories Issued: Travel impacts over Lookout Pass and Marias Pass by Monday afternoon.

- Slick Monday Morning Commute: Valley rain and snow will develop early Monday, making for a messy and potentially icy start to the work week in northwest Montana, potentially including Kalispell.

- Colder with Snow Banding Midweek: A sharp cold front Tuesday night will bring gusty winds and quick-hitting snow showers through Wednesday.

Quiet conditions this afternoon will quickly give way to an approaching Pacific storm. Winter Weather Advisories go into effect on Monday for higher mountain passes where travel impacts are most certain. In the valleys, a wintry mix is expected Monday, followed by a colder, windier period through the middle of the week.

Mountain Passes: Expect snow to begin overnight. Total accumulations of 4 to 8 inches are likely through Monday night, with higher amounts on the peaks. Blowing snow may reduce visibility.

Valleys: Light snow or a wintry mix will develop early Monday morning. Because temperatures will be near freezing, the Monday morning commute could be slick. By Monday afternoon, most valleys will transition to a rain/snow mix or all rain as warmer air moves in. North-central Idaho valleys will see primarily rain below 4,000 feet.

A cold front pushes through Tuesday evening and rain will turn back to snow in the valleys late Tuesday night.

Wednesday will feature gusty westerly winds and convective snow showers. These snow bands can cause sudden whiteout conditions even if total accumulations remain modest. The trend has been for the snow bands to develop earlier in the day and focus farther south, potentially bringing the highest impacts from near Lost Trail Pass and south and east.

Colder air settles in for the remainder of the week. While the main moisture plume exits, the region remains in a northwest flow pattern. This means, off-and-on light snow showers will continue, especially in the mountains, and temperatures are forecast to be closer to seasonal averages.

Early indications show another weak disturbance possible by Saturday, keeping the unsettled trend alive.

AVIATION

VFR weather conditions will generally prevail through the next 24 hours. Primary hazards are mountain snow and valley mixed precipitation is expected to begin in northwest Montana late tonight into Monday morning. Southerly winds also increase region wide through the day on Monday, gusting up to 25 knots by the afternoon with precipitation beginning to shift southward.

MSO WATCHES/WARNINGS/ADVISORIES

MT...Winter Weather Advisory from 5 AM Monday to 5 AM MST Tuesday for West Glacier Region.

Winter Weather Advisory from 1 PM Monday to 9 AM MST Tuesday for Lower Clark Fork Region.

ID...None.