textproduct: Glasgow

KEY MESSAGES

- Warm and dry conditions are expected the next few days, peaking on Wednesday. - A Red Flag Warning continues until 8PM for gusty NW winds expected with low relative humidity, with fire weather concerns returning by Wednesday. - The forecast becomes potentially windier and wetter Wednesday night into the weekend with scattered showers and isolated thunderstorms possible.

DISCUSSION

WEATHER PATTERN OVERVIEW: As a weak cold front passes through the area amid already dry and gusty conditions, there are isolated showers and thunderstorms forecast to occur between 4 PM and 9 PM. Some of the CAM models suggest severe gusts around 60 mph are expected to mix down, enhancing the synoptic gusts already around 50 mph. An 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 dry southerly flow, adding to ongoing fire weather concerns. A trough moves through Thursday and keeps winds elevated through at least Friday. This situation will be monitored closely for high wind and extended fire concerns.

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 lower humidity and increase winds through Wednesday based on high confidence in a dry pattern with fire weather concerns that the NBM has not been fully capturing lately.

There is high confidence on isolated to scattered showers and thunderstorms occurring through 9 PM today. There is very high confidence for fire and lake wind headlines being needed Wednesday, and in temperatures reaching the lower 90s for many locations. There is moderate confidence on a high wind and fire products being needed into Thursday and Friday as well. Confidence is low on Wednesday evening for thunderstorms being strong to severe as the trough moves through.

-JEZ

AVIATION

LAST UPDATED: 1900Z

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

DISCUSSION: An oncoming shortwave trough is bringing enough forcing to develop some cumulus and get a few showers or thunderstorms to develop late this afternoon and evening. The main threat is enhanced wind gusts along with brief visibility reduction from blowing dust. There is moderate confidence (50 percent) of MVFR conditions occurring at KOLF, KSDY and KGDV between 20Z and 03Z.

WIND: Mainly NW at 20 to 30 knots with gusts to 45 knots before 00Z, decreasing to around 10 knots overnight into Tuesday.

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

FIRE WEATHER

Critical fire weather is expected through early this evening with a Red Flag Warning for all fire zones. Persistent periods of elevated to critical fire weather will continue over the next several days, particularly Wednesday. An upper ridge pattern brings warm/dry conditions along with occasional disturbances that cause gusty/shifting winds and isolated dry lightning potential later in the week.

A frontal passage this morning continues to bring strong northwest winds with gusts to 50 mph into northeast Montana. With relative humidity down to around 10 percent being observed, solidly critical fire weather conditions are in play until early evening. Fire weather concerns are greatest across the eastern zones 120/122 where fuels are critically receptive. Western portions of zone 137 and zone 135 with some green up and more 100-1000 hour fuels are of less concern. The pattern the rest of the week remains warm and dry, presenting repeated elevated fire weather when winds pick up or shift. Tuesday is of moderate concern based on limited winds, and Wednesday is of high concern for fire weather products being needed, potentially lingering into Thursday or Friday based on strong winds. Wednesday has temperatures as high as the 90s, gusty southerly winds and RH as low as 10 percent. Poor opportunities for wetting rain exist through the rest of the week.

-JEZ

GGW WATCHES/WARNINGS/ADVISORIES

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

Red Flag Warning until 8 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.