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DISCUSSION

KEY MESSAGES:

- Bitterly cold temperatures are expected through the weekend with wind chills dropping as low as minus 45. A Cold Weather Advisory and an Extreme Cold Warning have been issued. - Temperatures are expected to climb to near normal next week.

WEATHER PATTERN OVERVIEW:

Overall steering flow remains from the northwest with a strong upper level low pressure center over central and eastern Canada and persistent high pressure ridge anchored over the eastern Pacific.

A very cold arctic high pressure in the central Canadian provinces will continue to spill over the international border into NE Montana today. This high will slide into the upper midwest by Saturday. With the edge of the arctic airmass pushed up against the Front Range, clouds and upslope snow chances will be mostly to the southwest of the CWA, allowing for generally clear skies. This will aid in dropping the low temperatures, although lack of fresh snow will be a hindrance. Wind chill values will approach Advisory or Warning levels, with the coldest reading occuring tonight through early Friday morning.

As the upper low off the California coast moves east toward the end of the weekend, temperatures are expected begin recovery closer to normal for next week.

FORECAST CONFIDENCE & DEVIATIONS: Deviations from NBM include hi-res data for PoPs and winds for the first 24 hours.

Confidence is MODERATE to HIGH for hazardous cold temperatures, beginning today and lasting through the weekend. The question will be, how deep and far west does the cold get for a warning.

AVIATION

MVFR to VFR. As a very cold high pressure pushes south into the region, a band of low VFR to MVFR clouds will move across the TAF sits. A little light snow is possible but a visibility drop is not anticipated. The clouds will clear out overnight, leaving dangerously cold temperatures, which could cause icing and equipment/operations problems leading into this weekend.

GGW WATCHES/WARNINGS/ADVISORIES

Cold Weather Advisory until 1 PM MST Sunday for Central and Southeast Phillips-Central and Southern Valley-Dawson-Garfield- McCone-Northern Phillips-Prairie-Southwest Phillips-Wibaux.

Extreme Cold Warning until 1 PM MST Sunday for Daniels-Eastern Roosevelt-Northern Valley-Richland-Sheridan-Western Roosevelt.