textproduct: Glasgow

KEY MESSAGES

- Very warm, dry, and breezy conditions today will raise fire weather concerns for areas generally south of the Missouri River.

- A chance for showers or an isolated thunderstorm exists Sunday morning, especially along the Canadian border. Those chances will shift to the MT/ND border by Sunday afternoon or evening.

- A more active weather pattern is expected for the week ahead with shower and thunderstorm chances to increase, though widespread heavy precipitation at this time appears unlikely.

DISCUSSION

WEATHER PATTERN OVERVIEW:

Upper ridging remains firmly established over the western U.S. for Saturday as a surface low pressure system tracks across southern Montana. This will lead to warm temperatures, low humidity, and breezy conditions, with a Red Flag Warning in effect for locations south of the Missouri River from noon until 8pm.

Developing northwest winds appear unlikely to persist near Lake Wind threshold this afternoon, so will hold off on any highlights for now. However, northeast winds look to increase this evening and overnight. It is noteworthy, that some of the HREF guidance does produce wind gusts above 30 mph for several hours near Fort Peck Lake. Blending NBM, NBM90, and some high resolution guidance however still produces winds that are shy of criteria. Given that the main impacts would be during the evening or at night, will let the day shift have one final look at the decision, but decided to hold off for now to to low confidence.

An initial shortwave looks to flatten the ridge for Sunday morning with a shower or thunderstorm along the Canadian border, and along the MT/ND Border later in the day. Generally zonal flow with various shortwaves look to continue at times through the balance of the week as a trough begins to set up over the Pacific Northwest. This will lead to cooler temperatures but more active chances for showers and thunderstorms each day. To that end, widespread heavy rainfall so far does not yet appear to be included in this forecast.

FORECAST CONFIDENCE & DEVIATIONS:

Confidence is high on warm, dry, and breezy conditions leading to fire weather concerns for Saturday. Winds were adjusted using NBM, NBM90, and high resolution guidance for an upward nudge given expectations with the low pressure system tracking through the region followed by the shortwave tonight and Sunday. Confidence is below average on whether these winds will be sufficient for Lake Wind criteria at Fort Peck Lake. There is however, a growing emergence of consensus on a more active though somewhat cooler weather pattern to unfold during the week.

AVIATION

LAST UPDATE: Saturday August 8 at 0545Z.

FLIGHT CAT RANGE: VFR.

DISCUSSION: Skies will remain clear to partly cloudy as a few mid and high level clouds pass across the region from time to time through the taf period. Haze from upstream wildfire smoke will also be present but not enough to likely restrict visibility.

WIND: East winds will range between 5 and 15 kts this morning, shifting northeast tonight as low pressure tracks through and increasing to a range of 10 to 20 kts with occasional stronger gusts.

FIRE WEATHER

Saturday will feature warm temperatures, afternoon humidity between 10 and 20 percent, and developing northwest winds ranging from 10 to 20 mph with gusts to 30 mph. These conditions in the presence of dry fuels will lead to high fire danger. A Red Flag Warning remains in effect for FWZs 122, 135, 136, and 137 from Noon until 8 pm Saturday. While breezy conditions are likely to continue Saturday night, relative humidity readings are likely to recover, resulting in improving fire weather conditions.

GGW WATCHES/WARNINGS/ADVISORIES

Red Flag Warning from noon today to 8 PM MDT this evening for Dawson/McCone/Prairie/Richland/Wibaux Counties-Southern Petroleum and Southern Garfield Counties-The Little Rockies-The Lower Missouri River Breaks including the Charles M Russell National Wildlife Refuge.