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DISCUSSION

KEY MESSAGES: - A wintry mix including freezing rain possible on Christmas Day.

- Another round of mixed precipitation possible Friday afternoon into Saturday morning. WEATHER PATTERN OVERVIEW: A broad ridge across the CONUS is expected to become more amplified through the week, with the east Pacific trough digging southward along with the Gulf of Alaska low. This will lead to a slow increase in the moisture streaming into Montana as the atmospheric river pushing into southern California spreads across the Great Basin.

With the weak winter thermal boundary over central Montana, as slight ripples occur in the flow and moisture increases, overrunning precipitation is possible. Thermal profiles with warm air aloft and colder boundary layer will create conditions for freezing rain over mainly the central part of the CWA from any precipitation that occurs, intermittently from Wednesday night through Saturday morning.

A stronger shortwave pushes through the ridge on Friday night for potentially the best chance for precipitation along with gusty winds and dropping temperatures. An arctic high slides through the northern plains on Sunday, with ridge rebounding quickly. FORECAST CONFIDENCE & DEVIATIONS: Increased pops slightly for tonight otherwise left NBM.

Moderate to high confidence for widespread freezing rain on Thursday, with lower confidence for the QPF amount.

AVIATION

Mostly VFR as mid level clouds continue to stream across the region.

GGW WATCHES/WARNINGS/ADVISORIES

None.