textproduct: Great Falls

KEY MESSAGES

- Much warmer temperatures expected today, although most locations will stay below freezing through the afternoon.

- Light snow showers are expected along the mountains through tonight.

- Temperatures moderate over the weekend, with all locations warming to well above normal by early next week.

DISCUSSION

- Meteorological Overview:

Light mountain snow showers will develop across the region on Friday with generally minimal accumulations expected through at pass level. Temperatures will continue to warm with highs in the 20s and 30s expected across the region at lower elevations this afternoon.

Continued moderation in temperatures will occur over the weekend and the upper level ridge amplifies over the Northern Rockies, with the stubborn cold prone valleys of North Central and Central Montana being the slowest to moderate initially. By early next week increasing southwesterly flow and subsequent downsloping will lead to further warming, with all location warming well above normal. While this southwesterly flow will usher in warmer temperatures it will also support daily chances for precipitation, especially over the mountains. -Moldan/thor

- Forecast Confidence & Scenarios:

Cold Tonight:

Locally enhanced winds in eastern Glacier, Toole, and Liberty counties have led to wind chills in excess of 25 below. As such, a Cold Weather Advisory was issued through 9 AM to account for when these winds are expected to let up in combination with warming temperatures.

Otherwise, tonight is expected to be the last bitterly cold night for North-Central Montana. Going forward temperatures slowly climb back up with the most significant warm-up expected on Monday.

Snow Today:

Light mountain snow is expected throughout the day today with a 10- 20% chance of some light flurries at lower elevations. Generally speaking, snowfall accumulations are expected to be less than an inch with a 20-30% chance for greater than 2 inches along the mountain peaks.

Warm and Windy Conditions Return Next Week:

Ensemble cluster guidance is in very good agreement about a strong upper-level ridge building over the western CONUS through the start of next week.

Although the temperature swing for Monday's highs will be a bit dramatic, it is well supported in the models with NBM probabilities sitting at 90% for highs greater than 50 across the lower elevations. Additionally, there is a 50% chance for highs on Monday to exceed 60 degrees for portions of the Northern Plains including Great Falls.

With the warmth comes the wind. While Monday and Tuesday may be breezy, there are growing signs in the models that Wednesday through at least Thursday could see even stronger winds across much of the region. How strong the winds get is still yet to be decided but next week is looking to err on the side of warm and windy. -thor

AVIATION

20/06Z TAF Period

A weak upper level weather disturbance shifting east across MT will bring an increase in mid level cloud-cover and some mountain obscuration by Friday morning. Scattered light snow showers/flurries will track east across primarily central and southwest MT Friday afternoon with mainly low-VFR ceilings expected at terminals but some brief MVFR visibility may also be associated. Surface winds remain relatively light with some increase in west to northwest winds for a period Friday afternoon. Hoenisch

PRELIMINARY POINT TEMPS/POPS

GTF 3 -7 27 5 / 10 0 20 10 CTB 4 -11 21 -2 / 0 10 20 10 HLN 19 1 30 8 / 10 0 20 10 BZN 22 -2 30 7 / 10 10 10 10 WYS 22 -17 22 -1 / 40 20 30 20 DLN 20 2 31 4 / 10 10 10 10 HVR 5 -13 16 -6 / 30 0 20 10 LWT 6 -5 29 4 / 20 10 30 30

TFX WATCHES/WARNINGS/ADVISORIES

Cold Weather Advisory until 9 AM MST Friday for Eastern Glacier, Western Toole, and Central Pondera-Eastern Toole and Liberty.