textproduct: Great Falls

KEY MESSAGES

- Strong winds are expected late Monday through Tuesday morning along portions of north-central and central Montana.

- A strong cold front on Wednesday has the potential to bring widespread strong winds across the region and periods of heavy snow along the Northern Rockies.

UPDATE

/Issued 757 PM MST Sun Dec 14 2025/

It will be warm, dry, and windy across North-central, Central, and Southwestern Montana tonight through tomorrow. For the update, the High Wind Warning for the Northern Rocky Mountain Front was cancelled as the winds there have decreased below warning levels and are not expected to increase again until tomorrow morning. Temperatures across the plains of North-central Montana were increased tonight through tomorrow morning to better reflect current observations and trends and the latest model guidance. The rest of the forecast is on track. -IG

DISCUSSION

/Issued 757 PM MST Sun Dec 14 2025/

- Meteorological Overview:

Stronger winds will continue through the rest of the afternoon along the Rocky Mountain Front where a High Wind Warning is in effect. The pressure gradient across the Rockies relaxes some tonight with strong winds diminishing but overall mid-level flow continues to increase with breezy to locally windy conditions becoming more widespread across the rest of north-central MT. This sets the area up for relatively mild temperatures tonight, especially across the plains with even warmer temperatures across the area Monday. The first of two shortwaves tracks east along/north of the Canadian border Monday night, flattening the upper level ridge with a period of strong westerly midlevel flow developing across the region Monday and continuing through Wednesday with the passage of a stronger shortwave.

Strong winds initially redevelop Monday afternoon along the Rocky Mtn Front before spreading east across adjacent portions of north- central MT and peaking overnight Monday night as low pressure and the associated upper level wave track across AB/SK. Favorable conditions for mountain wave wind enhancement are expected late Monday/Monday night supporting the potential for strong winds further east to the I-15 corridor and east across Cascade and Judith Basin counties.

Wednesday still still holds the potential for a particularly widespread/higher end wind event for the area as mid-level flow increases to 60-80kts across much of the area with a fairly potent shortwave and associated Pacific cold front tracking across the region. Strong cooling aloft and afternoon timing of this wave would support deep mixing and transport of the stronger winds to the surface across much of the area while also bringing the potential for convective showers (changing to snow with the frontal passage). Expect more details to evolve this week.

Cooling behind the Wednesday system is brief with a colder airmass glancing portions of north-central MT Wednesday night. While cooler than early this week, temperatures look largely to remain above average into the weekend. Hoenisch

- Forecast Confidence & Scenarios:

High Winds Today:

Strong winds will continue across the Northern Rocky Mountain Front through the rest of the afternoon before tapering off later in the evening. Based on trending observations and the latest model guidance no changes were needed to the High Wind Warning for today. Winds will calm overnight before the next shortwave arrives Monday morning.

High Winds Monday through Tuesday:

There is very good model agreement for high winds along the Rocky Mountain Front and into Cascade and Judith Basin counties. As such, the High Wind Watch was upgraded to a High Wind Warning.

A High Wind Watch was added through the same time period for a wider area of north-central Montana and the Little Belts. The latest HREF does show good upper level support for stronger winds across the area but there is still some doubt as to whether the stronger winds will reach the surface. For now the decision will be to wait for updated model guidance to decide whether these areas are in need of an upgrade to a warning.

High Winds Late Tuesday through Wednesday:

The third round of wind is currently expected to be the strongest with wind gusts up to 85 mph are possible along the Rocky Mountain Front with isolated higher gusts possible in wind-prone areas. Along the rest of north-central and central Montana, confidence is currently at 60% for wind gusts greater than 60 mph. As such, a High Wind Watch was issued for much of the region that encompasses these areas of higher confidence.

For now a good portion of Southwest Montana has been left out of the watch. The main reason behind that is there is too little confidence in high winds at lower elevations. Right now strong winds are primarily confined to the highest elevations in Beaverhead, Madison county except the Madison Valley, and southern Gallatin county. With minimal impacts currently expected along area roads and high-traffic destinations, the decision was made to leave them out for now with the understanding that if future model guidance trends in the direction of those strong winds reaching points of impact at lower elevations then the rest of Southwest Montana may need to be added to the High Wind Watch.

When it comes to Hill and northern Blaine counties, there is a bit of a tricky situation at hand. With winds out of the southwest there is certainly the potential for downsloping winds to produce high wind gusts off the Bears Paw. But the complicating factor is the strongest winds for that portion of the region are expected at night which is typically when atmospheric stability is the strongest. High winds are not out of the range of possibilities but with probabilities sitting at around 20-30%, these zones will be left out of the current watch with the understanding that updated model guidance could change the picture and make high winds a more likely scenario in Hill and northern Blaine counties.

Heavy Snow Late Tuesday through Wednesday:

The stronger system expected late Tuesday through Wednesday will bring colder air and a shot of moisture across western Montana impacting the Continental Divide. With this there is a concern for heavy snow with moderate to heavy snowfall rates on top of blowing snow as a result of the high winds that are expected to coincide with this system. As a result, a Winter Storm Watch was issued along the Northern Rockies with the potential for 8 to 15 inches of snow at lower elevations of the zone including Marias and Rogers Pass and higher amounts possible along the peaks.

As of now, blizzard conditions are not anticipated. But periods of visibility down to a quarter of a mile are possible along the Continental Divide including Marias and Rogers Pass. Slick roads and low visibility may make travel very dangerous at times and folks should consider delaying travel if possible.

Elsewhere across the region there is a chance for some light flurries at lower elevations and along the island ranges of central Montana. But amounts are on the light side and there is very low confidence in any amounts of significance at this point in time. -thor

AVIATION

15/06Z TAF Period

VFR conditions will prevail across all terminal during the duration of this TAF Period. It will be very windy at the KGTF and KCTB terminals from the middle of this TAF Period through the end of it. After 16/01Z there will be wind gusts in excess of 50 kts at the KCTB terminal and 40 kts at the KGTF terminal. There will be instances of low-level wind shear and mountain wave turbulence during the duration of this TAF Period across North-central, Central, and Southwestern Montana. -IG

HYDROLOGY

Mild daytime and overnight temperatures will lead to rapid melting of the recent snow across eastern portions of north-central MT. With initially frozen ground, much of the snowmelt is likely to remain on the surface and may lead to standing water. While overall impact to creek/stream levels is low, most creeks are likely to be frozen with potential for water flow over the ice or potentially back up in some creek bottoms. Hoenisch

PRELIMINARY POINT TEMPS/POPS

GTF 46 58 41 52 / 0 0 0 10 CTB 37 53 35 45 / 0 10 10 10 HLN 29 50 38 53 / 0 10 20 30 BZN 27 52 37 54 / 0 0 10 20 WYS 12 39 25 38 / 0 10 20 40 DLN 28 51 36 52 / 0 0 10 10 HVR 30 52 31 42 / 0 10 0 10 LWT 38 53 35 46 / 0 10 0 10

TFX WATCHES/WARNINGS/ADVISORIES

High Wind Warning from 5 AM Monday to 8 AM MST Tuesday for East Glacier Park Region-Eastern Glacier, Western Toole, and Central Pondera-Eastern Toole and Liberty-Northern High Plains-Southern High Plains-Southern Rocky Mountain Front.

High Wind Watch from Monday afternoon through Tuesday morning for Bears Paw Mountains and Southern Blaine-Eastern Pondera and Eastern Teton-Little Belt and Highwood Mountains-Northern Blaine County-Upper Blackfoot and MacDonald Pass-Western and Central Chouteau County.

High Wind Watch from Tuesday evening through Wednesday evening for Bears Paw Mountains and Southern Blaine-Big Belt, Bridger and Castle Mountains-Canyon Ferry Area-Cascade County below 5000ft-East Glacier Park Region-Eastern Glacier, Western Toole, and Central Pondera-Eastern Pondera and Eastern Teton-Eastern Toole and Liberty-Elkhorn and Boulder Mountains-Fergus County below 4500ft-Gallatin Valley-Gates of the Mountains-Helena Valley-Judith Basin County and Judith Gap-Little Belt and Highwood Mountains-Madison River Valley-Meagher County Valleys- Missouri Headwaters-Northern High Plains-Snowy and Judith Mountains-Southern High Plains-Southern Rocky Mountain Front- Upper Blackfoot and MacDonald Pass-Western and Central Chouteau County.

Winter Storm Watch from Tuesday evening through Wednesday evening for East Glacier Park Region-Southern Rocky Mountain Front.

High Wind Warning from noon Monday to 11 AM MST Tuesday for Cascade County below 5000ft-Judith Basin County and Judith Gap.