Rest Of Today...Breezy...snow. Areas of blowing snow. New snow accumulation of 3 to 5 inches. Southwest winds 15 to 25 mph. Chance of snow near 100 percent. Highs 26°F to 32°F.

Tonight...Windy...snow. Areas of blowing snow. Snow accumulation of 4 to 7 inches. Southwest winds 20 to 30 mph. Chance of snow near 100 percent. Lows 20°F to 26°F.

Wednesday...Very windy. Snow. Areas of blowing snow. Snow accumulation of 4 to 6 inches. Southwest winds 25 to 35 mph with gusts to around 50 mph increasing to 35 to 40 mph with gusts to around 55 mph late in the afternoon. Chance of snow near 100 percent. Highs 31°F to 37°F.

Wednesday Night...Very windy. Colder...snow. Areas of blowing snow. Snow accumulation of 2 to 3 inches. West winds 30 to 40 mph decreasing to 20 to 25 mph after midnight. Chance of snow near 100 percent. Lows 6°F to 12°F.

Thursday...Breezy...colder. Snow likely. Snow accumulation around 1 inch. Total snow accumulation 14 to 26 inches. West winds 15 to 20 mph. Chance of snow 60 percent. Highs 18°F to 24°F.

Thursday Night...Colder. Mostly cloudy in the evening then becoming partly cloudy. A 20 percent chance of snow. Lows -2°F to 4°F. Wind chill readings -13°F to -23°F.

Friday...Mostly cloudy. Slight chance of snow in the morning...then chance of snow in the afternoon. Chance of snow 30 percent. Highs 22°F to 28°F. Lowest wind chill readings -13°F to -23°F in the morning.

Friday Night...Mostly cloudy with a 40 percent chance of snow. Lows 9°F to 15°F.

Saturday...Cloudy with a 50 percent chance of snow. Highs 24°F to 30°F.

Saturday Night...Colder. Mostly cloudy with a 40 percent chance of snow. Lows 2°F to 8°F.

Sunday...Mostly cloudy with a 40 percent chance of snow. Highs 16°F to 22°F.

Sunday Night...Mostly cloudy. Chance of snow in the evening...then slight chance of snow after midnight. Chance of snow 30 percent. Lows -3°F to 3°F.

Monday...Mostly cloudy with a 20 percent chance of snow. Highs 18°F to 24°F.

 Hazardous Weather  Gibbon Falls Forecast  Mammoth Forecast  Midway Forecast  Norris Forecast  Old Faithful Forecast 

Mountain Weather

At 6:00 a.m. seven to nine inches of new snow has fallen throughout southwest Montana. A moist Pacific storm is driving through on a northwest flow. Mountain temperatures are in the teens Fahrenheit and ridgetop winds are blowing west to northwest at 25-35 mph. The storm is expected to pick up later this morning and last through Wednesday. Today winds will pick up to 30-40 mph and more snow will fall. By morning I expect 10 to 12 inches in the mountains.

Snowpack and Avalanche Discussion:

The Bridger, Madison, and Gallatin Ranges, the Lionhead area near West Yellowstone, and the mountains around Cooke City:

If you enter avalanche terrain today you will likely trigger an avalanche. Today is not a day to trifle with the snowpack. It's ornery and getting more dangerous as more snow falls and wind blows.

Last week we formed a weak layer at the surface that quickly became unstable once it was buried. This layer of small-grained facets is buried about a foot deep and is found on all aspects of the compass throughout our entire advisory area. In the last two days it was propagating fractures and avalanching. Our current snow storm is rapidly loading slopes increasing stress on this layer. On slopes with thin snow cover, like in the Bridger and northern Madison Range, I expect avalanches to step down to the ground on large, sugary grains of depth hoar. Avalanche activity is Mother Nature's warning sign that slopes are unstable. Activity includes:

• Outside of Cooke City on Saturday, Mark triggered a slide on this layer of near-surface facets. Yesterday, a snowboarder and his friends were able to trigger pockets on every run they took near Fisher Peak. The winds were ripping and loading slopes during the day and have not abated.

• I investigated an avalanche in Beehive Basin that ran 500 feet wide on Sunday on this layer. It broke to the ground in spots too.

• Skiers also triggered a large slide on Yellow Mountain on Sunday.

• Yesterday, a skier in Hyalite triggered two small pockets on steep slopes near Divide Peak when the snow broke on these facets.

• I saw debris from natural slides in the Bridger Range early Sunday morning near Sacajewea and Hardscabble Peak.

For today, the Avalanche Danger is rated HIGH on wind-loaded slopes steeper than 35 degrees with a CONSIDERABLE Avalanche Danger on all other slopes. Instability is widespread. If the storm continues the avalanche danger will rise further.

The next advisory tomorrow morning at 7:30 a.m. If you have any snowpack or avalanche observations, drop us a line at mtavalanche@gmail.com or call us at: 406-587-6984.

Beacon Parks

The Friends of the Avalanche Center installed a Beacon Training Park outside West Yellowstone. It's located south of town on the main snowmobile trail. Stop by and do a quick practice before heading off into the mountains!

EDUCATION, EVENTS, PHOTOS, SNOWPITS, and VIDEOS

1. We've recently uploaded more photos and snowpits to our web site, more than what are linked in the advisory.

2. We're creating a series of "How To…" stability test videos. So far we've got clips on performing a CT and ECT. There are located under Stability Tests on the Resources page.

3. Check out all our education programs, Click Here.

Information provided by Doug Chabot, Mark Staples, and Eric Knoff from the Gallatin National Forest Avalanche Center. For Events and Education, or Photos and Videos, please visit the Avalanche Centers Website!

If you have any snowpack or avalanche observations, drop them a line at mtavalanche@gmail.com or call: 406-587-6984.

For detailed Avalanche Terms utilized here, please see the Avalanche Glossary.