Today: Occasional flurries after 11:00 am. Patchy freezing fog before 11:00 am. Increasing clouds, with a high near 26°F. Wind chill values as low as -15°F.

Tonight: A 50 percent chance of snow. Mostly cloudy, with a low around 7°F. Wind chill values as low as -5°F. New snow accumulation of 1 to 3 inches possible.

Wednesday: Snow likely. Cloudy, with a high near 18°F and a low around -9°F. Night time Wind chill values as low as -25°F. Chance of precipitation is 70%. New daytime snow accumulation of 1 to 3 inches possible, with less than half an inch additional overnight.

Thursday: Occasional flurries before 11:00 am. Mostly sunny, with a high near 14°F and a low around -11°F.

Friday: Mostly sunny, windy, with a high near 17°F and a low around -3°F. Breezy, with a southwest wind 6 to 9 mph increasing to between 18 and 21 mph. Winds could gust as high as 31 mph.

Saturday: A 20 percent chance of snow showers. Partly sunny, with a high near 19°F and a low around 0°F.

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Mountain Weather

Mountain temperatures are in the high teens Fahrenheit this morning with west to north winds at 15-30 mph and gusts hitting 40 mph. Today will start sunny, but clouds will increase later this afternoon as a cold front brings snowfall late tonight. Steady 20-40 mph winds will blow ahead of the front with nighttime temperatures dropping into the low teens Fahrenheit. By morning I'm expecting 3 to 4 inches of snow with storm totals of 6 to 8 inches by Wednesday night.

Snowpack and Avalanche Discussion:

The Bridger and Madison Ranges, the southern Gallatin Range and the Lionhead area near West Yellowstone:

With the exception of the northern Gallatin Range and mountains around Cooke City our mountain snowpack is weak, thin and not impressive. According to the NRCS we are at 65% of normal. That's giving winter a below average grade of "D" and Mother Nature doesn't grade on a curve. Weak snow is defined as unsupportable, unconsolidated, and faceted. Every time I step out of my skis or off my snowmobile I sink to the ground confirming its presence. This snowpack will have a difficult time supporting future snows.

My partner and I skied into Beehive Basin in the northern Madison Range on Sunday and found two feet (at most) of sugary, weak snow. In order to have an avalanche we need 4 things: a steep slope, a weak layer, a slab of snow sitting on that layer and a trigger. In Beehive, as in many parts of our advisory area, the missing ingredient is the slab. On slopes with deeper snowpacks this slab exists, which is why the ski patrols were able to release a few avalanches this past weekend with explosives.

For today, the avalanche danger is a function of depth. On slopes where the snowpack is greater than two feet deep, mainly on wind-loaded slopes, a slab exists and the Avalanche Danger is rated MODERATE. On slopes with less than two feet of snow the Avalanche Danger is rated LOW.

The northern Gallatin Range and mountains around Cooke City:

Mark and Eric spent the weekend digging snowpits around Cooke City. This trip was on the heels of Mark's tour up Flanders drainage in the northern Gallatin Range. Although miles apart, there were some similarities. Three or more feet of snow was measured in both areas, plus faceted, weaker snow was found near the ground. Stability tests indicated this layer is slowly strengthening and they concluded it would take a large storm to get it to avalanche; however, buried facets are never to be fully trusted. Occasionally the test columns propagated fractures. These results indicate variability within the snowpack as well as the possibility of triggering a slide. A natural avalanche outside Cooke City on Sunday is further evidence of this possibility.

For today the Avalanche Danger is rated MODERATE on all slopes steeper than 35 degrees. All other slopes have a LOW Avalanche Danger.

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.

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.

Information provided by Doug Chabot, Mark Staples, and Eric Knoff from the Gallatin National Forest Avalanche Center. For 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.