textproduct: Missoula

DISCUSSION

KEY MESSAGES:

- Hard freeze coming for the mornings.

- Valley fog and stratus will be common early this week.

- A warming and drying trend this week.

- Another cold and cold front on the way for early next week.

The winter storm is winding down this morning as the upper level low over the Pacific northwest is migrating south today. Expect cool, cloudy weather today as both the moisture source and the source of the cold air are cut off from the region today. That being said, there's quite a bit of cold air already in our area from this storm.

Due to the cold air mass in place, increasing stability, and a drier air mass aloft moving, expect some very cold, foggy mornings ahead. The next few mornings will be a battle between how much it can cool off at night, and how much fog and stratus can form in the valleys to keep things warmer. In any case, there's plenty of potential for a hard freeze the next few mornings with temperatures in the low to mid 20s for much of western Montana. However, due to the recent moisture, as it gets cold at night that will be limited by fog formation. If the fog forms, temperatures in the mid to upper 20s are more likely in the mornings, but if there are breaks in the fog, especially in the high elevation valleys, then it will get quite cold quickly.

Through the week a ridge will build back in over the region. This will cause more stable conditions, limiting how quickly fog can burn off in western Montana. Central Idaho and far northwest Montana picked up far less moisture from this recent storm, so that will be less of an impact there. However, the building ridge will cause temperatures to rise to above average for this time of year by the end of the week.

Ensembles are starting to agree on another cold front for early next week, so the warmer, drier weather at the end of the week will only last a few days. So far ensembles are showing less potential for moisture with the next front, especially if it comes through as an open wave vs a closed low like this last one. So it wont' be a repeat of this system, but will probably come with more westerly winds, some precipitation, and a good cool down.

AVIATION

Ceilings and visibility will be a challenge today. Many areas have received a lot of moisture recently, and as the upper level low over the Pacific Northwest migrates south a ridge starts to build over the region today. So early today the region will battle low clouds and fog from all the recent moisture, then with the increasing stability overnight and latent moisture, fog will continue to be a problem in many area valleys for the next few days.

MSO WATCHES/WARNINGS/ADVISORIES

MT...Winter Weather Advisory until 6 AM MDT early this morning for Bitterroot/Sapphire Mountains...Potomac/Seeley Lake Region...West Glacier Region.

Lake Wind Advisory until 6 AM MDT early this morning for Flathead/Mission Valleys.

Winter Storm Warning until 6 AM MDT early this morning for Butte/Blackfoot Region.

ID...None.