textproduct: Great Falls

KEY MESSAGES

- Windy, unseasonably mild and dry conditions persist through the first half of the week and bring an elevated grassland fire risk to the plains.

- Strong winds with gusts in excess of 55 mph develop along the Rocky Mountain Front tonight with periods of strong wind gusts expected on Monday over much of North Central MT.

- Near record high daytime temperatures and unseasonably mild overnight minimum temperatures are expected through Wednesday.

UPDATE

Minor adjustments were made to the near-term forecast based on updated model guidance but otherwise no major changes were made to the going forecast. -thor

DISCUSSION

/Issued 419 PM MST Sun Jan 11 2026/

- Meteorological Overview:

A large scale upper level ridge currently centered across the interior western US will amplify while slowly shifting westward with its axis centered just offshore by the middle of the week in response to multiple shortwaves tracking over the ridge through northern BC and AB. The first series of waves tracking well north of the area will enhance the mid-level northwesterly flow over the ridge across the Northern Rockies and MT with 700MB winds increasing to 55-65kts across north-central MT by Monday morning. Strong wind gusts will develop this evening along the Rocky Mountain Front as the above ridgetop winds increase with favorable temperature profiles for mountain wave enhancement. Strong wind gusts are likely to expand further east across north-central MT on Monday, particularly in areas with terrain enhancement north/northeast of the Little Belts and near the the Island Ranges, with afternoon atmospheric mixing supporting a period of more widespread strong wind gusts across much of north-central MT.

Winds aloft decrease some and become less favorably aligned (more northwesterly)Tuesday and Wednesday as the ridge amplifies to our west with windy conditions persisting but with a lower risk of strong wind gusts. Unseasonably mild temperatures continue through Wednesday with daytime maximum temperature records likely to be challenged Tuesday and Wednesday as temps/heights peak before the ridge shifts offshore. Persistent winds and ample cloud-cover will also keep overnight temperatures mild, particularly across the north-central MT plains.

Model ensembles remain in reasonable agreement in the larger scale depiction of the the upper ridge axis near or just offshore of the west coast Thursday through next weekend. A more northerly flow will bring some cooling but most ensemble guidance keeps daily temperatures still slightly above seasonal averages for mid-January. GFS model members remain further west than the majority of medium range ensemble guidance with a more west trajectory of shortwave energy dropping south through the area on Thursday, which would bring some light precipitation and somewhat cooler temperatures. Hoenisch

- Forecast Confidence & Scenarios:

No changes were made to the High Wind Warnings already in effect or going into effect later tonight through Monday morning across N- central MT with winds already beginning to intensify this afternoon along the Rocky Mtn Front and locally near the Little Belts. Confidence remains high for gusts in excess of 50 mph across much of north-central MT with probabilities for gusts exceeding 65 mph as high as 50-70% near the central MT mountain ranges and 80% or higher along the Rocky Mtn Front. Favorable conditions for mountain wave enhancement support a 60% or higher risk of gusts in excess of 85 mph for areas immediately adjacent to the Rocky Mtn Front late tonight through early Monday with few isolated 100 mph gusts possible in the most favored locations.

Recent dryness and lack of snow-cover on the N-central MT plains has likely dried surface soil layers enough for a risk of localized blowing dust or alkali in areas more prone to this. This would most likely occur during peak afternoon heating/mixing Monday afternoon. Hoenisch

AVIATION

12/00Z TAF Period

Ridging aloft will remain in place over the Northern Rockies for much of the TAF period; however, strong west to northwesterly flow aloft will maintain windy conditions, mountain wave turbulence, and instances of low level wind shear, mostly along the Rocky Mountain Front and the plains. Increasing moisture aloft will stream towards the Continental Divide and obscure the mountains at times; otherwise, VFR conditions will prevail under passing mid- and higher level cloudiness. - RCG

FIRE WEATHER

Recent dryness and lack of snow-cover, along with persistent winds and above average temperatures will lead to increased fire danger in dormant grassland/rangeland fuels. Humidity remains particularly low (25% or less) across the north-central MT plains, where winds and cloud-cover only allowed for minimal RH recovery last night. A plume of Pacific moisture streaming over the upper ridge will gradually bring some slow humidity improvement through Monday and Tuesday, but overall dryness, unseasonable warm temperatures and windy conditions will produce an elevated grassland fire risk. Hoenisch

PRELIMINARY POINT TEMPS/POPS

GTF 43 57 47 60 / 20 0 10 0 CTB 38 53 41 55 / 10 0 0 0 HLN 33 52 38 55 / 10 10 10 10 BZN 27 50 33 53 / 10 0 10 10 WYS 8 35 12 37 / 0 0 0 10 DLN 26 48 31 52 / 0 0 0 0 HVR 35 55 38 52 / 0 10 10 0 LWT 36 57 43 55 / 0 0 10 10

TFX WATCHES/WARNINGS/ADVISORIES

High Wind Warning until 9 PM MST Monday for Eastern Glacier, Western Toole, and Central Pondera.

High Wind Warning from 8 AM to 9 PM MST Monday for Bears Paw Mountains and Southern Blaine-Cascade County below 5000ft- Eastern Pondera and Eastern Teton-Eastern Toole and Liberty- Fergus County below 4500ft-Hill County-Judith Basin County and Judith Gap-Northern Blaine County-Western and Central Chouteau County.

High Wind Warning until 9 PM MST Monday for East Glacier Park Region-Northern High Plains-Southern High Plains-Southern Rocky Mountain Front.