textproduct: Glasgow

KEY MESSAGES

- Red Flag Warning in effect until 9 PM this evening.

- Lake Wind Advisory in effect until 9 PM this evening with waves up to 5 ft. Isolated wave heights up to 6 ft.

- Potential accumulating rainfall from Saturday night through Tuesday. Overnight temperatures Monday and Tuesday are expected to be near freezing.

DISCUSSION

WEATHER PATTERN OVERVIEW: Strong 500 millibar zonal flow and cool temperatures (below -20 Celsius) will allow some scattered showers and thunderstorms to occur under windy conditions. There is potential for some of these gusts to exceed 50 mph during peak heating. The surface low will drift into western Ontario while a slow moving cold front drops south close to the Montana/Canada border. Winds are expected to come down after sunset.

An upper trough will continue to remain over the area for the next 5 days before breaking down a bit. In that time, a wave of moisture is expected to reach northeast Montana by Saturday night and continue through Tuesday. The latest GFS ensemble indicates there is a 50 to 100 percent chance of rain exceeding one tenth of an inch across the far west, east and northern parts of the area, with lesser amounts in the central parts. There is a 30 to 50 percent probability for half an inch of rain occurring. Scattered thunderstorms have the best opportunity for producing heavy rainfall, so half an inch of rain is possible in these storms. As the low pressure moves in, some CAMs indicate wind gusts exceeding 50 mph in the far southeast on Saturday night. Some of the models are showing it to be cold enough for snow during the day and night on Monday for the Little Rockies. Little accumulation is expected in this time though.

The upper trough begins to lift out Tuesday so a return to more normal conditions for this time of year can be expected.

FORECAST CONFIDENCE & DEVIATIONS: Increased PoPs manually to represent the latest CAM models for this afternoon.

There is moderate to high confidence in scattered showers and storms occurring across the northern half of the area this afternoon.

There is high confidence in precipitation occurring Saturday evening through Tuesday, but low to moderate confidence on total rainfall amounts.

There is high confidence wind gusts over 50 mph will occur across various parts of the area today.

AVIATION

LAST UPDATED: 1850Z

FLIGHT CAT RANGE: VFR, MVFR possible this afternoon.

DISCUSSION:

Gusty west winds are continuing through the day today, so patchy blowing dust, and scattered showers and thunderstorms may contribute to MVFR conditions between now and 8 PM this evening. There is moderate confidence (50 percent) of reductions in visibility occurring with the wind and rain. VFR conditions are expected after 8 PM.

WINDS: West northwest at 20 to 30 knots with gusts to 40 knots, decreasing to light and variable after 05Z.

GGW WATCHES/WARNINGS/ADVISORIES

Red Flag Warning until 9 PM MDT this evening for Dawson/McCone/Prairie/Richland/Wibaux Counties-Fort Peck Reservation and Daniels/Roosevelt/Sheridan Counties-Northern Valley and Northern Phillips Counties-Southern Petroleum and Southern Garfield Counties-The Little Rockies-The Lower Missouri River Breaks including the Charles M Russell National Wildlife Refuge.

Lake Wind Advisory until 9 PM MDT this evening for Central and Southeast Phillips-Central and Southern Valley-Garfield-McCone- Petroleum.