textproduct: Glasgow

KEY MESSAGES

- Hot high temperatures near 100 degrees are expected for today and Sunday. Look for little overnight recovery with lows tonight in the mid 60s to the mid 70s.

- Isolated to scattered dry thunderstorms are possible during this afternoon and evening. A few may be severe with particularly strong wind gusts in excess of 60 mph in the western part of the area.

- The hot and dry weather conditions will raise fire weather concerns at times over the next few days. A Red Flag Warning remains in effect for portions of the area for this afternoon and evening due to lightning.

DISCUSSION

WEATHER PATTERN OVERVIEW:

Upper ridging over the western U.S. will remain the dominant force this weekend with triple digit heat during the afternoon hours today and Sunday. Low temperatures tonight will struggle to get down to the mid 60s to mid 70s, making for uncomfortable sleeping conditions for those without air conditioning. The Extreme Heat Warning continues through 10pm Sunday.

There will be enough instability with a shortwave trough approaching from the southwest this afternoon and evening to initiate a few dry thunderstorms. HREF max ensemble wind gust guidance continues to support the potential for damaging wind gusts as a primary threat, further noting the inverted-v forecast soundings across the area. A Red Flag Warning for fire zones 134, 135, 136, and 137 continues for this afternoon due to the lightning risk on dry fuels. As an aside, haze and some smoke will continue at times to be a problem from upstream wildfires.

Ensembles continue to show the hot temperatures continuing through at least the early and middle part of next week, with highs in the 90s to around 100 degrees each day.

FORECAST CONFIDENCE & DEVIATIONS:

The only deviation was to expand the slight chance PoPs this evening and overnight.

There is moderate to high confidence in the heat products through tomorrow evening, and for thunderstorms to occur, especially in the southwest tonight. There is low confidence on the exact locations that a severe wind gust may occur though.

There is moderate to high confidence in smoke and haze reducing visibility between 1 mile and 6 miles through tomorrow evening. There is similar confidence in the Red Flag Warning for later today.

AVIATION

UPDATE TIME: Saturday July 25 at 1830Z.

FLIGHT CATEGORY: VFR prevailing, temporary MVFR possible with visibility reductions in thunderstorms and in haze.

SYNOPSIS: Upper ridging will continue to provide hot temperatures to the region. There is moderate to high confidence (50-80 percent) of haze and smoke impacting TAF sites from now through 12Z, and then a break between 12Z and 16Z, and then a more intense push after that time. There is potential for visibility to come down as low as 1 mile at times, but there is low (30 percent) confidence in this scenario. A shortwave trough moving through the ridge will aid in isolated to scattered thunderstorms from 01Z to around 09Z Sunday. Gusty winds are the primary hazard with this activity.

DENSITY ALTITUDE: Issues are expected at times with high temperatures near 100 today and Sunday.

WINDS: Light and variable becoming northwest at 7 to 16 knots after 15Z Sunday.

GGW WATCHES/WARNINGS/ADVISORIES

Extreme Heat Warning until 10 PM MDT Sunday for Central and Southeast Phillips-Central and Southern Valley-Daniels-Dawson- Eastern Roosevelt-Garfield-McCone-Northern Phillips-Northern Valley-Petroleum-Prairie-Richland-Sheridan-Southwest Phillips- Western Roosevelt-Wibaux.

Red Flag Warning from 4 PM this afternoon to 10 PM MDT this evening for 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.