textproduct: Glasgow

KEY MESSAGES

- Much cooler weather is expected tomorrow. Temperatures climb through the week, returning to mid 90s by Friday.

- Critical fire danger continues through the rest of the day due to warm, windy, and dry conditions. Red Flag Warning continues until 9 PM. Isolated dry thunderstorms are possible tonight.

- Areas of dense smoke will last through the evening. A Dense Smoke Advisory is in place until 6 PM.

- Increasing northwest winds today will cause impacts to recreation on Fort Peck Lake.

DISCUSSION

WEATHER PATTERN OVERVIEW:

The persistent upper ridge over the region is beginning to break down with a low pressure system moving across western Canada. With upper level troughing passing through the region, windy conditions still persist through the rest of the day. The cold front earlier this morning and increased 700 mb winds maintain gusty west northwest winds and continue to push a cooling airmass southeastward. The dry airmass and gusty winds will keep fire weather conditions at critical levels, so the Red Flag Warning will continue through 9 pm tonight. Winds will also be strong enough for Lake Wind Advisory for today and tomorrow. The windy conditions will bring additional smoke into the region from Washington and Oregon, for reductions of visibility and air quality. Areas of dense smoke will last through the evening. A Dense Smoke Advisory is in place until 6 PM.

A second cold front will arrive tonight into Monday as a trailing lobe of the upper low moves over the region. This will usher in another drop in temperatures for early in the week offering a relief from the heat and fire weather concerns. There may be an isolated to scattered dry thunderstorm tonight with this, and may warrant an extension of the Red Flag Warning due to receptive fuels. While ERC values have lowered below the 90th percentile, the location of highest chances for thunder overlap with areas of drier fuels.

Longer term, ensembles begin to show the trough moving downstream as a new ridge becomes established over the Pacific Northwest. This will extend height rises over eastern Montana with northwest flow aloft and moderating temperature toward seasonable averages late week.

FORECAST CONFIDENCE & DEVIATIONS:

While NBM handled the big picture well across the forecast, a blend with NBM90 was used for near term winds this weekend in line with the expected windy conditions supporting the Red Flag and Lake Wind headlines in effect.

AVIATION

UPDATED: 1930Z

FLIGHT CAT RANGE: VFR prevailing - IFR in dense smoke

DISCUSSION: Quiet weather into this evening with the exception of areas of dense smoke through the evening. Periods of IFR visibilities will be possible through 0Z. Low chances for lightning between 6 and 12Z tonight, but opted to leave out of TAFs at this time.

WIND: Northwest at 10 to 20 kts becoming north at 5 to 10 kts during the night. Gusty northwest winds 15 to 25 kts return after sunrise.

FIRE WEATHER

A Red Flag Warning is in effect for all fire weather zones across NE Montana (120, 122, 134-37) until 9PM MDT tonight. West northwest winds 15 to 25 mph and gusting to 35 mph continue through this evening. Taken together in the presence of dry fuels, these conditions will maintain critical fire weather conditions this evening. Lighter north winds are expected tonight, but the low confidence for isolated dry thunderstorms tonight may warrant an extension of the Red Flag Warning.

Hot temperatures this weekend will drop significantly following a cold front tonight. While min RH values remain lower in the 20 to 40% range, overnight recovery will be better. Winds will also become lighter by Tuesday. Thus, fire weather concerns should ease early next week. Temperatures rise and RH values drop after Tuesday.

GGW WATCHES/WARNINGS/ADVISORIES

Red Flag Warning until 9 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.

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

Dense Smoke Advisory until 6 PM MDT this evening for Central and Southern Valley-Dawson-Eastern Roosevelt-McCone-Northern Phillips-Northern Valley-Richland-Western Roosevelt-Wibaux.