January 22, 2013 Avalanche Advisory
The avalanche danger is LOW in the mountains of west central Montana. Avalanche conditions are generally safe but you still need to look for unstable snow on isolated terrain features such as recently wind loaded areas steeper than 35 degrees. On sun exposed slopes the avalanche danger will be elevated during the peak of solar heating.
Hello! This is Steve Karkanen with the January 22, 2013 avalanche advisory. This advisory is sponsored in part by the many people who came to last week’s Community Unite Pint Nite benefit for the West Central Montana Avalanche Foundation at the Northside Kettlehouse. It was a great turnout! Thank You!
Weather and Snowpack Analysis
It’s been more than 10 days since our last storm. A high pressure system has dominated our weather with clear skies, warm mountain temperatures and high winds at the higher elevations. Afternoon temperatures at many SNOTEL sites reached into the mid-thirties with warmer temperatures experienced on south facing aspects.
Overnight these temperatures drop well below freezing. At the higher elevations a persistent wind scoured many ridge tops and formed wind slabs on the more sheltered pockets. These wind slabs have gained strength over the past few days but it remains important to check that strength before committing. On southeast to southwest aspects observers in the Bitterroot, Swans and Rattlesnake noted small loose snow avalanches on the steepest sun exposed terrain. Cold temperatures at night will have these slopes locked up early in the day but pay attention to the possibility of wet snow avalanches as the sun heats the slope you are on.
North to east aspects are holding the best snow and we are not seeing significant results in stability testing. There is a layer of facets about a foot below the surface in some areas but there is no slab above it to be concerned with. However, if a wind slab has formed you want to dig down to see if it exists under that slab.
The warm temperatures, sun, wind and low humidity has limited surface hoar growth. You can find it in areas under the influence of the inversion or near bodies of water. In pockets sheltered from the sun and wind it may have survived but it is not a widespread condition. We are seeing near surface facets and radiation recrystallized snow particularly on sunny aspects and just under the wind or sun crusts.
The older surface hoar (buried about a foot deep) and the current snow surface will be the next watch outs during the next big storm.
Weather Forecast and Avalanche Outlook
NOAA Weather’s Missoula Office is forecasting another day or two of high pressure and elevated mountain temperatures. Wednesday afternoon, a moist north Pacific system will move into the Northern Rockies bringing gusty winds and moderate snow amounts.
This morning mountain temperatures are in the upper twenties with valley temperatures in the single digits. At 8000′ the wind is gusting from the northwest to 30 mph. We can expect another bluebird day perhaps again on Wednesday.
Expect the avalanche danger to increase during the peak of solar heating and when it starts snowing again.
I will issue the next advisory this Friday, January 25.
Are you missing a pack?
A fully loaded pack was found near Lolo Pass yesterday. Please send us an email at [email protected] or call 406-329-3752 (leave a message) and we’ll get you hooked up with the person who rescued your gear!