textproduct: Glasgow

KEY MESSAGES

- Warm conditions are expected the next few days, peaking on Wednesday. There is an opportunity for thunderstorms today, with a few strong to severe storms possible. - A Red Flag Warning has been issued for today for gusty northwest winds and low relative humidity. A Lake Wind Advisory is also in effect for today.

- The forecast becomes potentially wetter Wednesday night into the weekend with more scattered showers and isolated thunderstorms possible. High winds are possible Wednesday into Thursday, and a Lake Wind Advisory will likely be needed.

DISCUSSION

WEATHER PATTERN OVERVIEW: An oncoming warm front is expected to bring a few isolated showers and thunderstorms through about 10 AM today, then a bit of clearing and warming ahead of a surface cold front that will move through in the afternoon. There are scattered showers and isolated thunderstorms forecast to occur between noon and 9 PM. Some of the CAM models suggest severe gusts around 60 mph are expected in the strongest storms. It would not take very much to get to this threshold since strong northwest winds are already forecast to move through with the cold front. Strong boundary layer mixing aloft and pre- frontal warming will aid in bringing afternoon humidity readings below 20 percent. This combined with strong winds and a low greenness index will bring critical fire weather conditions. Upper ridge builds into the area on Tuesday with lighter winds and dry weather. A few random locations may reach criteria for red flag conditions on Tuesday in the east, but there is marginal evidence for this set up thus far.

On Wednesday the upper ridge axis moves through eastern Montana with the warmest day of 2026 so far expected. Some locations will likely have highs in the 90s with increased southerly flow, adding to ongoing fire weather concerns. These fire concerns are expected on Thursday too. As the trough Wednesday into Thursday moves through, the weather prediction centers is suggesting a few locations reaching high wind criteria. This situation will be monitored closely.

A more zonal flow pattern develops thereafter to moderate temperatures some and bring smaller synoptic ridge/trough couplets embedded in it. This will bring chances for showers and thunderstorms at times across the region through the weekend with possible wetting rains or even a marginal severe potential depending on whether it matches up with peak heating. Individual ensemble members continue to disagree on what day/time any given ridge/trough couplet moves through though.

FORECAST CONFIDENCE & DEVIATIONS: The main deviations were to increase winds in the afternoon, to increase PoPs, and increase thunder on Day 1. Also decreased relative humidity to line up with the Red Flag Warning for later today.

There is high confidence on isolated to scattered showers and thunderstorms occurring through 8 PM today, and high confidence in the Red Flag Warning timing and location. There is moderate (50 percent) confidence of these storms producing a severe wind gust.

There is moderate confidence on a fire weather product being needed on Tuesday. There is high confidence of a lake wind advisory being needed for Wednesday and Thursday, and in temperatures reaching the 90s for many locations. There is moderate confidence on a high wind product being needed Wednesday into Thursday as well.

Confidence is low on Wednesday afternoon for thunderstorms being strong to severe as the trough moves through.

AVIATION

LAST UPDATED: 0600Z

FLIGHT CAT RANGE: VFR, MVFR in thunderstorms and areas blowing dust.

DISCUSSION: An oncoming shortwave trough is bringing enough forcing to get a few showers and isolated thunderstorms going through the early morning. Then mid to high clouds clear out ahead of a surface cold front that will have enough forcing to get a few isolated thunderstorms going from 19Z to around 02Z Tuesday. There is moderate confidence (50 percent) of MVFR conditions occurring with these storms. There is also moderate to high confidence (50-70 percent) of blowing dust occurring for KSDY and KGDV in the afternoon as the front passes through.

WIND: Mainly south southeast at 6 to 16 knots, becoming northwest at 15 to 27 knots with gusts to 39 knots after 18Z, decreasing to 10 to 15 knots after 03Z Tuesday.

LLWS: South southeast at 30 to 40 knots for most TAF sites through 12Z, then northwest through 15Z before ending.

EQUIPMENT: No obs from KSDY. TAF will be AMD NOT SKED until obs return.

GGW WATCHES/WARNINGS/ADVISORIES

Lake Wind Advisory from 9 AM to 9 PM MDT Monday for Central and Southeast Phillips-Central and Southern Valley-Garfield-McCone- Petroleum.

Red Flag Warning from 11 AM to 8 PM MDT Monday 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.