textproduct: Great Falls

KEY MESSAGES

- Rain and snow become widespread today with a change to snow at lower elevations this afternoon.

- Winter weather impacts peak tonight as gusty west winds develop with temperatures falling below freezing before snow gradually ends from northwest to southeast through Friday morning.

- Drier conditions and seasonable temperatures return for the weekend into early next week.

- Cooler, potentially unsettled weather may return for the second half of next week.

DISCUSSION

/Issued 310 AM MDT Thu Apr 2 2026/

- Meteorological Overview:

A spring storm system is on track to affect the region today and tonight as a cold/closed mid-upper level low moving onshore in WA/OR early this morning tracks ESE reaching WY tonight. Numerous showers continue to move across the area this morning in the moist/diffluent flow ahead of the upper level low. A more organized area of precipitation, potentially including a few isolated thunderstorms, is expected to develop late this morning as an inverted surface trough of low pressure deepens across the area and colder air aloft associated with the mid-upper level low begins moving in from the west. Precipitation is most widespread this afternoon into this evening as the upper level circulation moves by to our south with moisture pivoting around it and focused within a mid-lvel TROWAL (TRough OF Warm Air aLoft). Snow levels around 6000-7000ft this morning rapidly fall to 4000ft or less this afternoon from west to east with primarily snow expected across the valleys and plains by this evening. Snow gradually ends from NW to SE across the area overnight for northern and western portions of the forecast area but lingers into Friday morning across eastern portions of central and southwest MT, where moist NW flow will continue to produce some additional measurable snowfall through Friday morning.

A NW flow aloft follows through this weekend as upper level ridging gradually builds to our west through early next week. This provides mainly dry conditions with temperatures returning to near or slightly above seasonal averages. Additional warming is possible Tuesday before the next round of cooler and unsettled weather develops for mid-late next week, though there is still a good deal of uncertainty in timing and details with troughing later next week. Hoenisch

- Forecast Confidence & Scenarios:

Snowfall amount forecasts have not significantly changed and overall winter weather impacts are on track. Newer model data does support somewhat higher snowfall amounts than previous forecasts over Bozeman Pass and the Bridger Range, and this combined with the potential for gusty winds and icing of road surfaces this evening has resulted in an upgrade to a winter storm warning for that zone. A winter weather advisory was also added for the Gallatin Valley, where snowfall amount forecasts range from around 1 inch at Belgrade to as high as 3-4 inches closer to the Bridger/Gallatin range, including the city of Bozeman and Gallatin Gateway area.

There is still considerable uncertainty in the timing of rain changing to snow and associated impacts across lower elevation portions of north-central MT, particularly across Cascade and Judith Basin counties and north along I-15. There is some potential for a narrower band of enhanced precipitation to develop this afternoon and evening beneath the TROWAL. In addition, the timing of rain changing to snow (early to late afternoon) may vary based on precipitation intensity, and even an early transition to snow may not be impactful this afternoon with air temperatures in the mid 30s.

It is important to note that while precipitation/snowfall rates may peak this afternoon, winter weather impacts are likely to become more widespread this evening as temperatures fall below freezing. In addition, gusty west to northwest winds will create additional reductions in visibility during the evening/overnight period. Hoenisch

AVIATION

02/12Z TAF Period

Showers increase from west to east this morning as a cold front moves into the region in association with an upper level low tracking into Idaho. Gusty winds and brief but intense precipitation are are possible with the initial showers followed by a more widespread degradation to MVFR/IFR conditions. A change from rain to snow is likely at most terminals this afternoon through this evening, also trending from west to east, with additional reduction of visibility. Hoenisch

PRELIMINARY POINT TEMPS/POPS

GTF 44 30 50 28 / 90 70 30 0 CTB 39 24 46 27 / 100 50 10 0 HLN 44 29 50 28 / 70 60 20 0 BZN 47 27 49 24 / 70 70 50 0 WYS 39 21 43 17 / 80 70 40 0 DLN 44 28 49 25 / 60 40 10 0 HVR 44 28 46 27 / 70 80 20 0 LWT 49 27 41 25 / 80 90 80 0

TFX WATCHES/WARNINGS/ADVISORIES

Winter Weather Advisory until 6 AM MDT Friday for East Glacier Park Region-Elkhorn and Boulder Mountains-Northwest Beaverhead County-Ruby Mountains and Southern Beaverhead Mountains-Southern Rocky Mountain Front-Upper Blackfoot and MacDonald Pass.

Winter Storm Warning from 9 AM this morning to noon MDT Friday for Big Belt, Bridger and Castle Mountains-Gallatin and Madison County Mountains and Centennial Mountains-Little Belt and Highwood Mountains.

Winter Weather Advisory from 3 PM this afternoon to noon MDT Friday for Cascade County below 5000ft-Fergus County below 4500ft-Gallatin Valley-Judith Basin County and Judith Gap-Snowy and Judith Mountains.