textproduct: Glasgow

KEY MESSAGES

- Widespread rain is expected most of today as the upper low moves from western Montana this morning to Saskatchewan tonight. - Strong west winds develop this afternoon and continue through Tuesday night.

- Cooler start and end to the week, with a brief warm up around mid week.

DISCUSSION

WEATHER PATTERN OVERVIEW: Eastern Montana will be in SW flow aloft ahead of an upper low moving into western Montana this morning and across Central Montana into SW Saskatchewan this afternoon. A humid airmass will combine with the moist SW flow aloft keep an unstable atmosphere over the forecast area which will allow for showers and thunderstorms at times. A few storms early this morning could become severe with large hail and damaging winds. PWAT on GGW 00z sounding was 1.46 inches which is a record high for September. This will provide stronger storms ample moisture for high rainfall rates especially this morning. As the low moves into Saskatchewan this afternoon and evening, a dry slot will move north across NE Montana gradually diminishing the rain from south to north. Meanwhile, the surface low will move north through NE Montana along MT 13 this morning and into Saskatchewan this afternoon where it will become stacked with the upper low. Strong west winds will develop across the forecast area this afternoon and continue tonight and Tuesday with gusts to 40 to 50 mph possible. A Lake Wind Advisory is in effect from noon today through midnight Tuesday night. Wrap around rain is possible at times tonight and Tuesday over the NW half of the forecast area while the SE will be dry most of the time.

The system exits the region Tuesday night and Wednesday and Thursday are expected to be dry.

FORECAST CONFIDENCE & DEVIATIONS:

High confidence on rain this morning with diminishing confidence for rain this afternoon. High confidence for strong west winds this afternoon, tonight and Tuesday. Tweaked pops early this morning. No other changes at this time.

AVIATION

LAST UPDATED: 0600Z

FLIGHT CAT RANGE: VFR most of the time with areas of MVFR this morning and tonight.

DISCUSSION:

Look for mix of low and mid clouds across the region today with rain and scattered thunderstorms producing MVFR conditions at times. Dry slot this afternoon and tonight will clear skies at times. Wrap around low clouds will bring MVFR CIGS at times late tonight and Tuesday

WINDS: East to NE 5 to 15 knots early this morning, wind will become variable between 12z and 20z today as a surface low moves through the area. Winds will become west 15 to 20 knots this afternoon as the surface low moves into Saskatchewan. West winds will be 15 to 25 knots tonight with higher gusts.

GGW WATCHES/WARNINGS/ADVISORIES

Lake Wind Advisory from 2 PM this afternoon to midnight MDT Tuesday night for Central and Southeast Phillips-Central and Southern Valley-Garfield-McCone-Petroleum.