textproduct: Great Falls

KEY MESSAGES

- Wildfire smoke will continue to impact the region through the end of the week.

- Hot, dry, windy conditions expected on Saturday and Sunday with elevated to critical fire weather concerns through the afternoon.

- A brief cool down is expected Sunday evening through Tuesday before temperatures start warming up again.

- Dry conditions are expected to persist over the next week.

DISCUSSION

/Issued 210 PM MDT Fri Jul 31 2026/

- Meteorological Overview:

The upper-level ridge pattern continues Friday which will bring another day of hot temperatures to the region. Drier PWATs and little forcing Friday will keep most of the region dry, but I can't rule out a few showers and thunderstorms in Southwest MT during the afternoon. Temperatures peak on Saturday as the ridge breakdowns and southwest flow increases. Lower elevations are forecasted to reach into the 100s across north-Central MT and the upper 90s in Southwest MT. The ridge breakdown also brings an increase in 700mb winds through Sunday, peaking late Saturday night into early Sunday morning to 60-70kts along the Northern Rocky Mountain Front. As a result, strong winds develop along the Rocky Mountain Front windy conditions develop elsewhere Saturday and Sunday. This with the combination of hot temperatures and low relative humidity creates concerns for elevated to critical fire weather conditions (see FIRE WEATHER section).

A mostly dry frontal passage Sunday will help bring a relief in the heat through the first half of next week. Northwest flow aloft will help keep temperatures down through Tuesday, before very warm temperatures return. Low moisture throughout the week will keep conditions dry. -Wilson

- Forecast Confidence & Scenarios:

Weekend Heat:

Model agreement remains high on the potential for widespread high temperatures in the upper 90s to upper 100s on Saturday. The previous Extreme Heat Watches have now been upgraded to Extreme Heat Warnings with additional Heat Advisories added for surrounding areas.

Cascade county and the lower elevations of Judith Basin county will get hot during the day but manage to cool off. Chouteau and Fergus counties along with the Bears Paw zone will be more at risk for maintaining the warm overnight lows which will provide additional heat stress. Thus the Cascade and Judith Basin warnings will end earlier while the Chouteau, Fergus, and Bears Paw warnings will continue until around the time the cooler air from the front is expected to reach those zones. The Gallatin and Madison Valley zones were added to the Extreme Heat Warning based on the expected highs compared to climatology. Both Bozeman and Ennis are at risk for having a top 10 high temperature event on Saturday which means this kind of heat is generally on the rare side for these areas and may have greater impacts for both residents and those recreating in the area. Given that these two valleys will cool off Sunday morning, these warnings will also drop off earlier compared to the North-Central Montana zones.

Supplemental Heat Advisories were issued for surrounding areas to bring attention to locations that might not get as hot or have as significant impacts but still be a concern for those who are without air conditioning or plan on spending a significant amount of time outdoors.

Strong Winds Saturday/Sunday:

There is still strong model agreement in strong winds developing over the Rocky Mountain Front Saturday afternoon through Sunday morning with the strongest winds expected between midnight and 8 AM Sunday. With these winds being well outside of climatology for this time of year, the potential for impacts to those recreating along the Rocky Mountain Front, and the overall confidence in the event occurring, the decision was made to upgrade the watch to a High Wind Warning. Additionally, with there being strong hints in the models that the front could arrive a little earlier, the High Wind Warning will start at noon on Saturday to account for this possibility.

Across the rest of the region gusts between 35 and 50 mph are possible with most locations outside the warning unlikely to reach high wind criteria. But there still will be a concern for those traveling along north-south roads as locally stronger crosswinds in some of the typical wind-prone areas may make travel difficult for high profile vehicles and those towing trailers. -thor

AVIATION

01/00Z TAF Period

VFR conditions will prevail across all terminals during this TAF Period. Across all terminals after 01/18Z winds will begin to increase with the strongest winds being at the KCTB terminal. At the KCTB terminal by the end of this TAF Period winds will gust in excess of 30 kt. Across most of the TAF sites smoke from wildfires will reduce slantwise visibility. -IG

For KGTF: Winds will be light through 18Z. Between 18Z and 00Z winds will increase and shift from the southwest to the west. Between 21Z and 00Z there is a 50% chance for a 15 kt crosswind. -IG

FIRE WEATHER

Elevated to critical fire weather conditions are expected Saturday afternoon through Sunday evening across North-Central, Central, and Southwest Montana.

On Saturday, highs in the upper 90s to upper 100s combined with minimum RH values as low as 8%. Winds will start to pick up in the afternoon with a wind shift from the south/southwest to the west as the cold front arrives. Gusts up to 50 mph are possible along the Northern Plains with gusts up to 75 mph possible along the immediate eastern slopes of the Rocky Mountain Front.

Poor overnight RH recovery into Sunday morning is expected with maximum RH values in the 20-40% range. Even though Sunday afternoon will be cooler, RH values are still expected to drop into the upper single digits to mid teens through the afternoon with frequent gusts over 35 mph. This will raise concerns not only for ongoing fires but any potential new starts that occur.

Given the expected threat for critical fire weather conditions, the watch has been upgraded to a Red Flag Warning from Saturday afternoon to Sunday evening. -thor

PRELIMINARY POINT TEMPS/POPS

GTF 60 102 61 86 / 0 0 0 0 CTB 54 97 54 76 / 0 0 0 0 HLN 60 100 60 85 / 0 0 0 0 BZN 57 100 57 91 / 0 0 0 0 WYS 47 91 48 87 / 0 0 0 0 DLN 55 94 54 88 / 0 0 0 0 HVR 57 105 61 86 / 0 0 0 0 LWT 58 100 59 86 / 0 0 0 0

TFX WATCHES/WARNINGS/ADVISORIES

Heat Advisory from noon Saturday to 3 AM MDT Sunday for Beaverhead and Western Madison below 6000ft-Canyon Ferry Area- Eastern Glacier, Western Toole, and Central Pondera-Eastern Pondera and Eastern Teton-Eastern Toole and Liberty-Elkhorn and Boulder Mountains-Gates of the Mountains-Helena Valley-Hill County-Meagher County Valleys-Missouri Headwaters-Northern Blaine County-Snowy and Judith Mountains.

Red Flag Warning from 2 PM Saturday to 9 PM MDT Sunday for Central and Eastern Lewis and Clark National Forest Areas- Chouteau and Fergus Counties-Eastern Glacier/Toole/Central/Eastern Pondera/Liberty-Helena and Townsend Ranger Districts of the Helena National Forest-Hill and Blaine Counties-Lewis and Clark National Forest Rocky Mountain District-Rocky Mountain Front-Lincoln Ranger District of the Helena National Forest.

High Wind Warning from 6 PM Saturday to noon MDT Sunday for East Glacier Park Region-Eastern Glacier, Western Toole, and Central Pondera-Northern High Plains.

Extreme Heat Warning from noon Saturday to noon MDT Sunday for Bears Paw Mountains and Southern Blaine-Fergus County below 4500ft-Western and Central Chouteau County.

Extreme Heat Warning from noon Saturday to 3 AM MDT Sunday for Cascade County below 5000ft-Gallatin Valley-Judith Basin County and Judith Gap-Madison River Valley.