textproduct: Glasgow

KEY MESSAGES

- Some thunderstorms this afternoon and evening may produce severe wind gusts and brief heavy rainfall.

- A Lake Wind Advisory continues for Fort Peck Lake through 6 PM MDT Sunday.

- Gusty winds return during the day tomorrow. Strongest winds will be in Sheridan, Daniels, and eastern Roosevelt county.

- Temperatures will recover for the second half of the week with highs each day largely in the 80s.

DISCUSSION

WEATHER PATTERN OVERVIEW:

A cold front and upper trough will deliver a combination of lower temperatures, increasing west to northwest winds, and continued showers and thunderstorms through this evening. SPC maintains a Marginal Risk for the east, and a small area of slight risk over Wibaux county, where severe wind gusts are a concern. These locations will see the warmest daytime temperatures and more unstable atmospheric conditions. Overall, HREF shows timing as early as 18Z for the wind threat emerging, with activity evolving east by evening hours. A few of the storms may produce locally heavy rainfall as well. Long, narrow tracks of updraft helicity greater than 75 m^2/s^2 present the possibility of isolated supercells clipping our CWA.

The Lake Wind Advisory for Fort Peck Lake remains in effect until 6 PM MDT. Windy conditions will relax during the evening but ramp back up tomorrow. That said, an additional Lake Wind Advisory has been issued for tomorrow from 6 AM to 6 PM MDT. The strongest winds will be in Sheridan, Daniels, and eastern Roosevelt county, for a brief period, gusting near headline criteria.

Upper ridging will then guide warmer and drier conditions to NE Montana for Tuesday. The ridge axis looks to slide east late in the week with diffluent southwest upper flow becoming established over the Northern High Plains. In short, the next round of thunderstorms may get underway as early as Wednesday evening.

FORECAST CONFIDENCE & DEVIATIONS:

Adjusted Pops using HiRes ARW for near term collaboration and consistency. Following an increase in PoPs, adjusted PoT to match the SVR threat for this afternoon. Upped winds using 33% NBM90 for today, and 50/50 NBM/NBM90 for winds and wind gusts Monday.

Confidence is also increasing on more active weather in the form of thunderstorms by midweek as the ridge translates downstream, supported by dynamic lift and increased instability.

AVIATION

LAST UPDATED: 1830Z.

FLIGHT CAT RANGE: VFR, MVFR in thunderstorms.

DISCUSSION: An upper trough will help maintain shower and thunderstorm chances across area terminals through 0Z.

WINDS: West at 10 to 20 kts, gusting to 30 kts. Winds look to diminish after 2Z Sunday.

GGW WATCHES/WARNINGS/ADVISORIES

Lake Wind Advisory until 6 PM MDT this evening for Central and Southeast Phillips-Central and Southern Valley-Garfield-McCone- Petroleum.

Lake Wind Advisory from 6 AM to 6 PM MDT Monday for Central and Southeast Phillips-Central and Southern Valley-Garfield-McCone- Petroleum.