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KEY MESSAGES

- Saturday could be the hottest day of the summer with temperatures possibly reaching close to 110 in places. A Excessive Heat Watch has been issued that covers Saturday night as low temps Saturday night are expected to be in the low to mid 70s in most places.

- Northwest winds ramp significantly Sunday in the wake of a frontal system. Critical fire weather conditions can be expected with very low humidities (~10%) and winds 15-25 mph with possible gusts to 40 mph.

- There will be an overall cooldown across the region next week, with a near 20-30 degree high temperature dropoff between Saturday to Monday.

DISCUSSION

WEATHER PATTERN OVERVIEW:

Showers continue to drift through parts of northeast Montana this afternoon. With daytime heating, some storms could also pop up, but consistent cloud cover across the region likely would be an inhibiting factor for any strong to severe storms.

Another disturbance may move in from central Montana Thursday night and exit Friday, then the heat is on with temps reaching the 90s to around 100 and going further Saturday with only the northeast zones reaching the 90s while the rest of the CWA is expected to reach 100 to 110.

An excessive heat watch has been issued for the entire CWA Saturday through Saturday night as overnight temps will only fall into the 70s then rebound into the low to mid 90s Sunday.

But northwest winds ramp significantly Sunday in the wake of a frontal system. Winds of 15 to 25 mph with possible gusts to 40 mph are possible. Combined with very low humidity (~10% in many places), this will likely be a critical day for Fire Weather. But winds do look to back off late in the day that could bring some relief.

By Monday, afternoon high temperatures across the region could be in the 70s and 80s, which would be a 20-30 degree cooldown from Saturday. A slow warmup is expected thereafter.

FORECAST CONFIDENCE & DEVIATIONS:

High confidence in the hot weather Friday and Saturday. Confidence is increasing for critical fire weather conditions Sunday. Low confidence in timing any showers and thunderstorms.

No major deviations from the base forecast were made for this iteration.

Cliff

AVIATION

FLIGHT CATEGORY: VFR.

DISCUSSION: Mainly dry conditions are expected into Thursday evening but isolated showers and storms are possible Thursday morning mainly KGDV and KSDY, possibly KGGW Thursday evening. Any haze from distant fires will lower Slantwise visibility. Outside of some isolated precipitation in the far northeastern areas, Friday looks to be mainly dry.

WINDS: Overall East or Southeast winds will hover at 10 kts through Friday. Any thunderstorms that form this afternoon in addition to the ongoing showers, could lead to erratic and gusty winds.

DENSITY ALTITUDE: Will be a concern especially Saturday with temperatures near or over 100. Extra power and longer runway will be needed for takeoffs.

Cliff

FIRE WEATHER

Fire weather concerns will be low to moderate through Friday even with the continued heat, as winds will generally be fairly quiet.

Starting Saturday afternoon, however, concerns quickly ramp up to being near critical in advance of a dry cold front moving through the region Saturday evening. The concerns for critical fire weather come to an apex on Sunday, as widespread RH values are expected to be in the low teens while winds are likely to be in the 20 to 30 mph range and temperatures remain in the upper 80s to upper 90s.

While not zero, there is a low chance of dry lightning on Sunday as well, which would only work to add to the fire weather concerns. While the situation will need to continue to be monitored, Fire Weather headlines are expected to be needed in the coming forecast cycles.

GGW WATCHES/WARNINGS/ADVISORIES

Extreme Heat Watch from Saturday afternoon through Sunday morning for Central and Southeast Phillips-Central and Southern Valley-Garfield-Northern Phillips-Northern Valley-Petroleum- Southwest Phillips.

Fire Weather Watch from Saturday afternoon through Sunday 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.

Extreme Heat Watch from Saturday afternoon through Sunday afternoon for Daniels-Dawson-Eastern Roosevelt-McCone-Prairie- Richland-Sheridan-Western Roosevelt-Wibaux.