textproduct: Great Falls

KEY MESSAGES

- Hot temperatures through Saturday before a cooldown Sunday through the first half of next week.

- Hot, dry, and windy conditions Saturday and Sunday bring criitical weather conditions across the region.

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

- Dry conditions settle in into next week.

DISCUSSION

- 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 Southest 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 Moutnain Front windy conditions develop elsewhere Saturday and Sunday. This with the combination of hot temperatures and low relative humdiity 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 fllow aloft will help keep temepratures down throguh Tuesday, before very warm temperatures return. Low moisutre throughout the week will keep conditions dry.

- Forecast Confidence & Scenarios:

Heat this Weekend:

There remains good confidence in imapctful heat setting up Saturday across the region, especially North-Central MT. Based on recent temeprautre trends this week wiht the wildfire smoke, the NBM may be running up to few degrees too hot for Saturday. However, there is good confidence for widespread temepratures in the 100s across North- Central MT Saturday. Therefore, the current heat products remain on track.

Winds Saturday and Sunday:

Models have been consitstent on the increase in winds and the timing of peak winds. There is a 30-60% chance for 60 mph winds along the immediate eastern slopes of the Rocky Mountain Front. Although this is a typically windy region, it will be unusually windy for the time of year, as wind gusts exceed the 95th percentile for August. Therefore, these wind speeds are more imapctful for the time of year. The main imapct will be for outdoor recrecreation, particualry for Glacier NP and those traveling in high profile vehicles. -Wilson

AVIATION

31/06Z TAF Period

A few showers and thunderstorms will slowly diminish through 09Z across the region. A few more instances of gusty and erratic winds near these decaying showers or thunderstorms will be a concern before activity fully diminishes.

Looking ahead to Friday, wildfire smoke will continue to be around, but the primary impact looks to be slant-range visibility, with surface visibility looking to remain in the VFR range. A few thunderstorms near the Idaho border cannot be ruled out late Friday, but confidence in impacts at KWYS was too low to warrant mention at this time.

For KGTF: Aside from a rogue outflow boundary the remainder of the evening, light winds look to persist through at least the late- morning hours Friday. Northwesterly winds look develop by early afternoon, though the magnitude of wind looks to remain 10 kts or less. The probability that this northwesterly wind results in a 15+kt cross wind Friday afternoon is less than 10%. -AM

FIRE WEATHER

Elevated to critical fire weather conditions is expected Saturday afternoon through Sunday evening across North-Central, Central, and Southwest Montana. On Saturday, hot temperatures in the upper 90s to near 108 degrees will combine with minimum RH values as low as 8% and frequent gusts of 25 to 40 mph with gusts up to 50 mph. Higher gusts are expected along the Rocky Mountain Front to create the potential for critical fire weather conditions. Sunday will be cooler but low RH values and stronger winds than Saturday are still expected which will still pose a significant concern not only for ongoing fires but any potential new starts that occur. A Fire Weather Watch remains in effect from Saturday afternoon through Sunday evening across all of North-Central, Central, and Southwest Montana. -thor/Wilson

PRELIMINARY POINT TEMPS/POPS

GTF 95 60 96 61 / 0 10 0 0 CTB 92 54 91 54 / 0 0 0 0 HLN 94 59 95 61 / 20 40 0 0 BZN 93 56 94 58 / 20 40 0 0 WYS 85 45 88 47 / 10 20 0 0 DLN 89 53 90 56 / 20 70 0 0 HVR 96 58 97 57 / 10 20 0 0 LWT 91 58 92 59 / 30 20 0 0

TFX WATCHES/WARNINGS/ADVISORIES

Extreme Heat Watch from Saturday afternoon through late Saturday night for Cascade County below 5000ft-Eastern Pondera and Eastern Teton-Judith Basin County and Judith Gap.

Fire Weather Watch from Saturday afternoon through Sunday evening 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 Watch from Saturday evening through Sunday morning for East Glacier Park Region-Eastern Glacier, Western Toole, and Central Pondera-Northern High Plains.

Extreme Heat Watch from Saturday afternoon through Sunday morning for Bears Paw Mountains and Southern Blaine-Fergus County below 4500ft-Western and Central Chouteau County.