textproduct: Great Falls

KEY MESSAGES

- Light snow will continue along the Hi-Line and Rocky Mountain Front through tomorrow morning.

- It will be windy through tonight along the Southern Rocky Mountain Front.

- It will be cold tomorrow across the plains of North-central Montana before it warms up Sunday through early next week.

DISCUSSION

- Meteorological Overview:

This afternoon there is an upper-level ridge over North-central, Central, and Southwestern Montana. An upper-level shortwave will move through the upper-level flow this afternoon through tonight. This combined with a strong surface pressure gradient will bring strong winds to the Southern Rocky Mountain Front down to MacDonald Pass. A cold front moved through North-central Montana this morning stopping just south of Great Falls along the Montana Highway 200/US Highway 87 corridor. The portions of the plains of North-central Montana north of the Montana Highway 200/US Highway 87 corridor will be cool today and cold tomorrow due to the cold front. Also due to the shortwave passage and cold frontal passage along the Rocky Mountain front and portions of the Hi-Line and Fergus County will see light snow through tomorrow morning. Tonight a secondary push of cold air will move through North-central Montana. On Saturday an upper-level ridge builds in over North-central, Central, and Southwestern Montana this will keep warm and dry conditions for Southwestern Montana. On Saturday North-central Montana will be cold with most locations well below seasonal averages for high temperatures. On Sunday the upper-level ridge remains over North- central, Central, and Southwestern Montana which will allow temperatures across the plains of North-central Montana to begin to warm up on Sunday. It will also be dry across the area.

On Monday and Tuesday the upper-level ridge remains over North- central, Central, and Southwestern Montana. This will keep warm and dry weather across the area. On Wednesday and Thursday an upper- level trough begins to move over North-central, Central, and Southwestern Montana. This will bring precipitation to much of Southwestern Montana. -IG

- Forecast Confidence & Scenarios:

From now through Saturday morning there is greater than a 50% chance for 1 inch of snow or greater across the Northern Rocky Mountain Front, Northern Hill County, and most of Blaine County. As a result Winter Weather Advisories remain in effect for Blaine County and the Northern Rocky Mountain Front through tomorrow morning. In addition in eastern Fergus County where up to an inch of snow is possible a Winter Weather Advisory will take effect tonight and continue through Saturday morning. For winds there was a high enough probability plus enough models showed the potential for mixing strong winds down that the High Wind Warning for the Southern Rocky Mountain Front and MacDonald Pass was extended to last until 11 PM tonight.

There is high uncertainty in temperatures this afternoon through tomorrow across North-central Montana. Temperatures were decreased from NBM through tomorrow across North-central Montana to better match current observations and trends.

Wednesday through Thursday there is greater than a 70% chance for 4 inches of snowfall or greater across the Mountains of Southwestern Montana. -IG

AVIATION

27/18Z TAF Period

Gusty westerly winds will start to pick up towards the afternoon along the Rocky Mountain Front and across portions of Central and Southwest Montana through the afternoon. Scattered to broken mid to high-level clouds will linger across the region with some instances of mountain obscuration possible along the Continental Divide and Southwest Montana through the first 6 hours of the TAF period.

MVFR/IFR clouds and light snow increase over the Hi-Line after 28/00Z with the main impacts expected along the Rocky Mountain Front and the Hi-Line east and south of Havre. Mountain obscuration will remain a concern across Central and North-Central Montana through the remainder of the TAF period after 28/00Z. -thor

PRELIMINARY POINT TEMPS/POPS

GTF 19 35 19 53 / 10 10 0 0 CTB 11 29 12 50 / 20 0 0 0 HLN 30 50 26 53 / 0 0 0 0 BZN 27 55 27 56 / 0 0 0 10 WYS 12 42 19 43 / 0 0 10 30 DLN 29 54 31 55 / 0 0 0 10 HVR 12 29 12 44 / 40 20 0 0 LWT 21 35 19 50 / 10 20 0 0

TFX WATCHES/WARNINGS/ADVISORIES

Winter Weather Advisory until 2 AM MST Saturday for East Glacier Park Region.

Winter Weather Advisory until 11 AM MST Saturday for Bears Paw Mountains and Southern Blaine-Northern Blaine County.

High Wind Warning until 11 PM MST this evening for Southern High Plains-Southern Rocky Mountain Front-Upper Blackfoot and MacDonald Pass.

Winter Weather Advisory from 5 PM this afternoon to 11 AM MST Saturday for Fergus County below 4500ft.