textproduct: Great Falls

KEY MESSAGES

- A round of accumulating snow and gusty northerly winds arrives tonight into Thursday, mostly impacting the Rocky Mountain Front, the Hi-Line, and areas over and adjacent to the Little Belt Mountains.

- A warming and drying trend pushes temperatures back above average this weekend into early next week.

- a passing disturbance may bring some breeziness and a chance for showers heading towards the middle of next week.

UPDATE

/Issued 848 PM MDT Wed Apr 2 2025/

Evening update has been published, with the primary adjustment being to increase PoPs by an additional 10-20% over the plains of North Central Montana where confidence continues to grow in accumulating snow through the overnight hours tonight and into portions of the day on Thursday, especially in areas covered by the Winter Weather Advisory. Otherwise the remaining updates resulted in no significant changes from the previous forecast. Current suite of Winter Weather Advisories highlight the potential spread of snowfall accumulations and associated hazards well, with latest radar imagery supporting and uptick in precipitation spilling east from the Continental Divide as the upper level shortwave approaches the Northern Rockies this evening. Latest Hi-Res Ensemble Forecast (HREF) guidance continues to support a period of moderate to at times heavy snow falling along and north of the US Hwy 2 corridor from Marias Pass to Havre from midnight tonight through 6 AM MDT Thursday, with snowfall rates of 1/4" to 3/4" per hour occurring across this region. These higher snowfall rates will lead to snow covered and slippery roadways, which will make for a hazardous morning commute on Thursday for these areas and even outside of the current advisory area as even light accumulations on roadways can lead to slippery conditions. - Moldan

DISCUSSION

/Issued 848 PM MDT Wed Apr 2 2025/

- Meteorological Overview:

The steadier snows from this morning continues to wind down as the responsible low pressure system moves away from the region; however, a weakly unstable boundary layer has been left in its place and is now initiating scattered rain/snow showers and even a few rumbles of thunder. This activity looks to persist through the afternoon before the next shortwave trough brings in the next opportunity for accumulating snow.

The snow initially picks up along the Rocky Mountain Front and the Hi-Line tonight and then moves southward into Central/North- central Montana and eventually Southwest Montana on Thursday. There will also be a brief period of gusty northerly winds behind the front, but strong winds are not expected. This system will be fairly quick moving with snow ending in a north to south fashion by Thursday evening through the overnight hours.

Ridging aloft slowly builds over the Northern Rockies heading into the weekend for warming and drying conditions. An overall mild pattern continues into next week, though passing disturbances may increase winds and shower chances Tuesday and Wednesday. -RCG

- Forecast Confidence & Scenarios:

Accumulating snow tonight and on Thursday...

The shortwave that brings the next round of snow tonight will be supported by H500/H700 temperatures down to -30/-20C respectively. Today's suite of model guidance has picked up on this with a marked increase in QPF across the board, but especially along the Rocky Mountain Front, the Hi-Line, and areas near and adjacent to the Little Belt Mountains. Most of these locations will see amounts in the 3 to 6 inch range with some higher amounts in the Marias Pass and Glacier National Park areas. As mentioned above, there will also be a period of gusty northerly winds that accompanies the snow. I did expand the winter weather advisories along the Rocky Mountain Front to include all of the Hi-Line and the Bears Paw/Little Belt Mountains. Some consideration was given for further expansion over the plains and parts of the southwest, but the core of the shortwave's energy does move off to the east rather than moving directly south. additionally, most of the forecast snow amounts were less than 2 inches. Snow ends for most locations by Tuesday night. - RCG

AVIATION

03/06Z TAF Period

A cold front pushing southward across Montana will bring a mix of VFR to IFR conditions with LIFR conditions possible in heavier snow showers. Expect snow to mainly be found around KCTB, KGTF, and KHVR through 12z before snow spreads further south to KHLN, KBZN, and KEKS Thursday morning. Snow showers capable of LIFR conditions will be possible during the daylight hours on Thursday. While they have not been put into the TAFs at this time, the greatest threat for LIFR conditions will exist at KHLN, KEKS, and KBZN. Ludwig

Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information.

PRELIMINARY POINT TEMPS/POPS

GTF 42 27 34 19 / 50 40 90 30 CTB 38 23 33 14 / 40 90 100 10 HLN 45 26 42 22 / 60 20 70 40 BZN 44 23 44 21 / 80 30 60 70 WYS 41 13 40 16 / 50 50 60 60 DLN 42 25 45 23 / 60 40 40 40 HVR 44 24 37 17 / 20 90 100 10 LWT 40 23 34 18 / 50 20 70 40

TFX WATCHES/WARNINGS/ADVISORIES

Winter Weather Advisory until 6 PM MDT Thursday for East Glacier Park Region-Eastern Glacier, Western Toole, and Central Pondera- Northern High Plains-Southern High Plains-Southern Rocky Mountain Front.

Winter Weather Advisory until 6 PM MDT Thursday for Bears Paw Mountains and Southern Blaine-Eastern Toole and Liberty-Hill County-Northern Blaine County.

Winter Weather Advisory from 9 AM Thursday to midnight MDT Thursday night for Little Belt and Highwood Mountains.