textproduct: Glasgow

KEY MESSAGES

- Slight chances for isolated showers through early this morning near the North Dakota border. Highest chances are concentrated in the SE Yellowstone Valley.

- Warm, dry, and gusty conditions on Tuesday will be cause for fire weather concerns.

- The first major frost of the season is possible along river bottoms Thursday morning.

DISCUSSION

An upper-level ridge over the Central US is interacting with an upper-level low over NORCAL and an upper-level trough over Manitoba/Ontario, producing SW flow aloft over Montana. Minor perturbations moving throughout the flow may create localized areas of instability, potentially producing isolated showers through early this morning near the North Dakota border. Primarily trace precipitation is anticipated, although there is potential for a hundreth or two in the SE Yellowstone Valley.

The Canadian trough and ridge over the Central US will exit eastward while the low over NORCAL digs south and becomes cut-off over southern Nevada by Tuesday morning. The low's associated trough will encompass the majority of the Intermountain West, somewhat stiffling potential trough development over Canada and enabling predominantly zonal flow over Montana through Wednesday morning. Subsequent warm, dry, and gusty conditions Tuesday will be cause for fire weather concerns.

An upper-level low in northern Manitoba will begin to dig south Wednesday, warping zonal flow into an upper-level trough that will reach as far south as South Dakota. An associated front will produce Wednesday night temperatures cool enough to possibly result in frost on river bottoms. Individuals with outside plants that are still alive may wish to bring them inside beforehand.

The cold will not be long-lived; a developing high-pressure ridge over the West Coast will build over NE Montana by Thursday.

Agreement between models begins to break down at this point, but an oncoming upper-level trough is anticipated to dig over Montana sometime between Friday night and Saturday afternoon. Confidence in timing is low, but enjoy the fair weather in the meanwhile.

FORECAST CONFIDENCE & DEVIATIONS:

- Low to moderate confidence in chances for showers through this morning.

- Low to moderate confidence in FireWx Tuesday afternoon.

- Moderate confidence in partial frost Thursday morning.

DON

AVIATION

LAST UPDATED: 0630Z

FLIGHT CAT RANGE: VFR - MVFR

DISCUSSION: BKN/OVC with low and mid clouds this morning with MVFR conditions around KGDV. Rain showers possible early this morning around KOLF, KSDY, and KGDV. Mid-level, potentially MVFR, ceilings will remain through this afternoon. Skies will scatter out by this evening.

SFC WIND: E-SE at 04 to 08 knots, becoming light and variable by this afternoon.

GGW WATCHES/WARNINGS/ADVISORIES

None.