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DISCUSSION

KEY MESSAGES:

- A wintry mix of rain, snow and freezing rain is expected today through Thursday evening.

- A strong winter storm with accumulation is possible Thursday evening through Saturday morning.

- Bitter cold temperatures are expected Thursday night through Saturday night.

WEATHER PATTERN OVERVIEW:

Model agreement continues to increase, allowing forecast confidence to reach better than average levels for the upcoming series of winter storm systems set to push through the region.

A fluctuating front will be the focus for precipitation and the border between rain and snow over the next few days. Model data and expected environmental conditions continue to support the chances for freezing rain between those two. With the wintry mix and possible ice accumulation, a winter weather advisory remains in effect for snow between 1 and 4 inches and ice between a trace and 0.10 inch between today, tonight, and Thursday.

That weather system will almost seamlessly morph into the weekend snow storm. A winter storm watch has been issued for portions of northeast Montana where model data indicate significant accumulating snow could amount to 5 to 12 inches. More specific data will become available in the day or two, but generally expect less amounts in the northeast corner of the state and much higher amounts toward central Montana.

Bitter cold air moves into the region Thursday night and remains over the area through Saturday night with lows below zero in all areas and wind chills below -20 north.

FORECAST CONFIDENCE & DEVIATIONS:

Average to high confidence on the mixed precipitation occurring today, tonight and Thursday, along with fluctuating temperature boundaries.

Average to high confidence on the accumulating heavy snow in the SW half of the forecast area between from Thursday through Saturday with lower confidence in the specific snow amounts for the NE corner zones.

High confidence on the bitter cold temperatures Thursday night through Saturday night.

AVIATION

LAST UPDATED: 0900Z, Wednesday morning 12/10

FLIGHT CAT: VFR, becoming a mix of MVFR/IFR in snow and low clouds this afternoon and remaining MVFR/IFR tonight.

DISCUSSION: Increasing mid level clouds will move into the area early this morning with low clouds and snow moving by 18-21z today. The snow will mix with rain and freezing rain at times tonight and Thursday morning with significant icing possible. Between Thursday night and Saturday morning, a significant snow storm is likely with accumulations

WIND: Variable winds less than 10 knots early becoming east to SE 5 to 15 knots this morning and continue this afternoon. SE to south winds 5 to 15 knots are expected tonight.

GGW WATCHES/WARNINGS/ADVISORIES

Winter Weather Advisory until 8 PM MST Thursday for Central and Southeast Phillips-Central and Southern Valley-Daniels-Dawson- Eastern Roosevelt-Garfield-McCone-Northern Phillips-Northern Valley-Petroleum-Prairie-Richland-Sheridan-Southwest Phillips- Western Roosevelt-Wibaux.

Winter Storm Watch from Thursday evening through Saturday morning for Central and Southeast Phillips-Central and Southern Valley-Dawson-Garfield-McCone-Northern Phillips-Petroleum- Prairie-Southwest Phillips.