textproduct: Glasgow

KEY MESSAGES

- Warm temperatures expected today.

- Some scattered rain showers and isolated thunderstorms are possible tonight.

- Colder temperatures and widespread rain showers are expected Sunday night and Monday.

DISCUSSION

WEATHER PATTERN OVERVIEW:

Upper ridge that was over Montana on Friday will move to the east today turning the flow aloft to the SW. The upper low currently off the Pacific Coast near California and Oregon will move slowly inland over the weekend. Meanwhile, a shortwave trough ahead of the low will move inland over California this morning and reach Montana tonight. Warmer air will move into the area ahead of the trough today with highs in the 70s in most areas. The wave will bring chances for showers and thunderstorms to the forecast area tonight with a cold front.

Chance for showers will continue on Sunday with somewhat cooler temperatures.

Beginning Sunday evening, the upper low to the west transitions into an open trough and the SW flow aloft brings more moisture into Montana with widespread showers with a chance of thunderstorms Sunday night and Monday. Models and ensembles differ on how quickly to move the upper trough through the forecast area. At this point, the NBM lingers chances for showers through Tuesday in some areas.

The next system will bring chances for showers beginning either Wednesday afternoon or evening with colder temperatures starting on Thursday.

FORECAST CONFIDENCE & DEVIATIONS:

Only deviations from the NBM Cron was slight adjustments to winds mixing in the best agreement from hi-res model data.

There is high confidence in temperatures today, and moderate confidence beyond today.

There is low confidence in the exact placement and timing of thunderstorms outflow winds this evening, but there is moderate confidence in the overall threat of convective storm activity tonight.

There is high confidence in rain Sunday night and Monday. There is low to moderate confidence in precipitation amounts through Monday.

AVIATION

LAST UPDATE: 0430Z, Saturday April 11

FLIGHT CAT RANGE: VFR

DISCUSSION: Look for gradually increasing high and mid level clouds today. Chances for scattered showers and isolated thunderstorms increase by this evening from SW to NE. Specifics for TAF sites will become evident later today. Some amendments for strong and gusty winds may be needed.

LLWS: Wind shear will continue early this morning with SE wiind 40 to 50 knots within 2000 feet AGL.

WINDS: SE at 10 to 15 knots with a few stronger gusts early this morning. SE to south winds will diminish to 5 to 10 knots this morning and veer to the SW this afternoon. Winds will become variable this evening with possible outflows from showers and thunderstorms and turn to the west at 5 to 15 knots late tonight. Stronger winds will be possible in thunderstorm downdrafts and outflow winds this evening.

GGW WATCHES/WARNINGS/ADVISORIES

None.