textproduct: Missoula

DISCUSSION

KEY MESSAGES:

- Cold mornings with valley fog for much of the rest of the week.

- A warming trend through the end of the week with Friday 10 to 15 degrees above average.

- Cold trough and cold front coming for early next week, though most of the precipitation will probably got further south.

A cold, stable air mass left behind the last cold front to come through will make for some cool mornings at high elevations and in valleys where it stays clear for a good portion of the night. A hard freeze is expected in those areas. But satellite is showing some of the residual moisture and melting snow is causing low stratus clouds to form, which are keeping the overnight lows up in much of western Montana and the Clearwater and Nez Perce mountains of central Idaho.

The stable conditions will continue as a ridge builds over the region. Today is the last day of the week that temperatures will be below average, and by Friday they'll be 10 to 15 degrees above average for this time of year. These stable conditions will make it a challenge to ventilate out the valleys and get rid of all the stratus by the end of the week, so most valleys are only expected to cool into the mid-20s to low 30s most of the rest of the week.

Ensembles continue to show another trough and cold front coming across the region early next week. About 60 percent of ensembles show an open wave and the rest of the models show a cutoff low diving to the south. All the models are showing mild to modest amounts of precipitation. The biggest difference in the patterns would be where the snow level ends up, with the 60 percent solution favoring lower snow levels.

AVIATION

Low clouds and fog continue to be a threat with a moist boundary layer, melting snow in the mountains, and stable conditions due to a building ridge. Current observations across the region including satellite are favoring more stratus and low ceilings than fog at this time. This will continue to be a challenge for the next few days, especially overnight with multiple hours of VFR and MVFR conditions expected at regional airports.

MSO WATCHES/WARNINGS/ADVISORIES

MT...None. ID...None.