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KEY MESSAGES

- An upper-level trough is producing areas of precipitation across Northeast Montana and will continue through Monday.

- Much cooler than average temperatures expected Sunday and Monday before warming back up by the end of next week.

- Snow accumulations possible in the Little Rockies and areas of higher elevations along the Canadian border. A winter weather advisory has been issued for Southwest Phillips County.

DISCUSSION

An upper-level low over the Pacific Northwest is continuing to dig southward into the western US. This setup has allowed for Pacific moisture to be transported into Montana. Combined with a surface cold front that moved through the region, some showers are already occuring and should persist through Monday.

Forecast QPF totals for the next couple of days have trended higher compared to previous model guidance. Much of the region could see as much as half an inch to an inch of total precipitation with lower amounts in far southeastern zones. Initially much of the precipitation will fall as rain. Rain will then mix with and change to snow tonight over the Little Rockies as temperatures fall while wet snow will be possible Sunday evening through Monday morning elsewhere across the CWA. Accumulating snow should remain more concentrated in northwestern counties along the immediate Canadian border and the higher peaks of the Little Rockies.

Accumulations overall should remain very little, if any, as warm ground temperatures will prevent snowfall from sticking to the ground with the exception of the Little Rockies and higher elevations along the Canadian border. Terrain-enhanced lift may cause localized heavy snowfall at times, producing locally higher amounts of up to a few inches of snowfall accumulation in some areas described. As a result, a Winter Weather Advisory has been issued for Southwest Phillips County, though a wide range in snowfall totals is expected depending on elevation.

Temperatures for Sunday and Monday will be much cooler than average due to cold Canadian air lingering along the backside of the cold front. Beyond Monday, temperatures should gradually warm up as an upper- level cutoff low develops over the Four Corners region and advects warmer air into the CWA.

Model agreement deteriorates significantly beyond Wednesday, so confidence remains low for weather conditions for the end of the week.

FORECAST CONFIDENCE & DEVIATIONS:

Confidence of below average temperatures through Monday are high but decreases as the week progresses and becomes low by the end of the week. Precipitation chances later in the week depends on the track of the low pressure system over the Four Corners.

While confidence in QPF amounts have trended higher, precipitation type, timing, and snow accumulation remain below average. Temperatures could trend cooler than forecasted due to evaporative cooling effects, however, warm ground temperatures still remain and will prevent much accumulating snow from sticking with the exception of the Little Rockies. Temperatures will continue to be monitored for changes in winter weather impacts.

KENZ

AVIATION

LAST UPDATED: 0610Z

FLIGHT CAT RANGE: MVFR to IFR conditions through the TAF cycle.

Discussion: MVFR conditions expected as ceilings continue to lower across the region Sunday morning. IFR ceilings are expected to drop in over KGDV by 15Z, followed by KGGW and KOLF at 17Z. KGGW and KOLF could have overcast ceilings as low as 900 ft tomorrow morning and KGDV as low as 600 ft. Ceilings should lift back up to MVFR heights during the afternoon hours before dropping back down to IFR ceilings Sunday evening and night.

Winds: Northerly winds and gusty conditions are expected to back northeast. Winds will sustain at 10-15 kts throughout the forecast period.

Icing: G-AIRMETS have been issued for all terminals. Moderate icing can be expected above 5,000 ft in KGGW and KOLF and decrease to 3,000 ft throughout the day. Expect moderate icing above 11,000 ft over KSDY and KGDV.

KENZ

GGW WATCHES/WARNINGS/ADVISORIES

Winter Weather Advisory from noon today to noon MDT Monday for Southwest Phillips.