textproduct: Glasgow

KEY MESSAGES

- Rain will be likely across northeast portions of Montana Sunday afternoon through Monday morning. Precipitation totals will range between 0.01" and 0.25".

- A Lake Wind Advisory has been issued due to wind speeds being expected to reach 20 to 25 mph sustained Sunday afternoon. Wave heights have the potential to reach 3 ft.

- Winds will likely reach Lake Wind Advisory criteria again Monday afternoon. Wave heights have the potential to reach 4.5 ft.

DISCUSSION

Zonal westerly flow aloft south of an upper-level trough in Central Canada will continue transporting moisture into the region, producing cloudy skies today.

An Eastern-Pacific trough will move onshore over Oregon by tomorrow morning before digging over Western Montana by mid- afternoon. Instability and low-level moisture associated with the trough will likely produce rain across northeast portions of Montana Sunday afternoon through Monday morning. Precipitation totals will range between 0.01" and 0.25".

SE surface winds will reach speeds of 20 to 25 mph sustained Sunday afternoon, with gusts potentially reaching 35 mph, therefore a Lake Wind Advisory has been issued. Winds will veer westerly Monday as zonal flow aloft becomes predominant and the trough begins exiting eastward. Winds of comparable strength reaching advisory criteria are expected. Wave heights have the potential to reach 4.5 ft, particularly Monday afternoon.

The trough will fully exit the region overnight Monday while the zonal flow left in its wake begins building into a weak ridging pattern. Slight chances for rain showers are possible Tuesday night into Wednesday morning due to a swath of low-level moisture moving throughout. Confidence in rain amounts are low. Rain chances dimish Wednesday afternoon as skies clear and temperatures warm under the ridge through the remainder of the week.

FORECAST CONFIDENCE & DEVIATIONS:

There is moderate to high confidence in sustained winds at or above 20 mph on Sunday and Monday across Fort Peck Lake.

There is low confidence in rain amounts Tuesday night into Wednesday.

DON

AVIATION

LAST UPDATED: 2000Z

FLIGHT CAT RANGE: VFR

DISCUSSION: Expect clouds to scatter out and rise this evening and overnight. A mid-level SCT cloud deck will likely redevelop tomorrow morning between 10,000' and 12,000' AGL before lowering and thickeing into the evening as precipitation becomes imminent.

W-NW wind at 5 to 10 kt this afternoon will veer N this evening. Wind will then become SE and increase to 15 to 20 kt by tomorrow morning.

DON

GGW WATCHES/WARNINGS/ADVISORIES

Lake Wind Advisory from 10 AM Sunday to midnight MDT Sunday night for Central and Southeast Phillips-Central and Southern Valley-Garfield-McCone-Petroleum.