Yellowstone Seven Day Forecast on 06 January 2011 by the NWS Riverton, WY

Rest Of Today: Cloudy with a 50 percent chance of snow. Highs 23°F to 29°F. Southwest winds around 15 mph late in the morning.

Tonight: Mostly cloudy with a 50 percent chance of snow. Lows 11°F to 17°F.

Friday: Mostly cloudy with a 40 percent chance of snow. Highs 25°F to 31°F.

Friday Night: Chance of snow in the evening...then snow likely after midnight. Snow accumulation of 1 to 2 inches. Lows 11°F to 17°F. Chance of snow 70 percent.

Saturday: Snow likely in the morning...then snow in the afternoon. Snow accumulation of 2 to 3 inches. Highs 21°F to 27°F. Southwest winds around 15 mph in the afternoon. Chance of snow 80 percent.

Saturday Night: Colder. Snow in the evening...then chance of snow after midnight. Light snow accumulations. Lows -4°F to 4°F. Chance of snow 80 percent. Wind chill readings -11°F to -21°F.

Sunday: Colder. Mostly cloudy with a 40 percent chance of snow. Highs 6°F to 12°F.

Sunday Night: Colder. Mostly cloudy with a 20 percent chance of snow. Lows -4°F to -14°F.

Monday: Mostly cloudy with a 20 percent chance of snow. Highs 3°F to 9°F.

Monday Night: Mostly cloudy in the evening then becoming partly cloudy. A 20 percent chance of snow. Lows -6°F to -16°F.

Tuesday: Partly cloudy with a 20 percent chance of snow. Highs 9°F to 15°F.

Tuesday Night: Partly cloudy with a 20 percent chance of snow. Lows -3°F to 3°F.

Wednesday: Mostly cloudy with a 20 percent chance of snow. Highs 13°F to 19°F.

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

Avalanche Information - from the Gallatin National Forest Avalanche Center this report is by Mark Staples

Mountain Weather:

An additional inch or two of snow fell in the past 24 hours. This morning temperatures were in the low 20s Fahrenheit at 9000 feet except near Cooke City and West Yellowstone where temperatures were closer to 10 degrees Fahrenheit. Only slightly lower elevations have temperatures approaching 30 degrees Fahrenheit. Strong winds yesterday continued this morning blowing 15-30 mph from the West. Warm air advection and tight pressure gradients in the weather models mean today's weather will be warm and windy with temperatures in the high 20's to low 30's and 15-30 mph West winds. Some snowfall is expected, but no more than an inch should accumulate. This weekend, however, looks promising for snow and colder weather.

Snowpack and Avalanche Discussion:

The northern Madison Range:

Doug and I went to Buck Ridge yesterday, just south of Big Sky, where there was about a foot of new snow though it seemed much deeper in spots. This new snow had been scoured from ridgetops by strong winds, and ski patrols on Lone Mountain easily triggered wind slabs and new snow avalanches with both explosives and ski cuts. Buried surface hoar, about 2-3 feet deep, has plagued the mountains near Big Sky. In our stability tests yesterday, this layer required moderate force to break but did not propagate fractures despite the significant stress of new snow, and we couldn't find any natural avalanches on this layer. This surface hoar layer has generally gained strength but not at the same rate on all slopes. In some areas, as skiers found high in Beehive Basin on Tuesday, this layer remains weak.

With significant new snow and wind, fresh wind slabs are the main concern today and the Avalanche Danger is CONSIDERABLE on all wind loaded slopes. All other slopes have aMODERATE Avalanche Danger.

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

Stability evaluations in the rest of the advisory area are much simpler. The snowpack lacks widespread, persistent weak layers, and the main problem will be fresh wind slabs which should be easy to identify and avoid. With warm weather these wind slabs should begin to bond but will remain sensitive today. The winter season and the snowpack are still young, and areas of weak snow can be found. While these areas are isolated, their existence reminds us to remain attentive. Often we can identify these areas by feeling changes in the snow under our skis or our track. Assessing stability with a snowpit is always a good idea, but it is especially so if the snowpack suddenly feels different.

For today, the avalanche danger is CONSIDERABLE on wind loaded slopes where human triggered avalanches are likely. For slopes without wind deposits, the Avalanche Danger is rated MODERATE on all slopes steeper than 35 degrees while lesser angled slopes have a LOW Danger.

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

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

Gallatin National Forest Avalanche Center ~ Mammoth Weather Forecast