Issued by Dave Bingaman - Payette Avalanche Center THIS AVALANCHE ADVISORY EXPIRED ON February 12, 2017 @ 7:33 am Avalanche Advisory published on February 11, 2017 @ 7:33 am The Avalanche Danger is Considerable today above 7000 feet where new windslabs formed through Thursday night and Friday on leeward slopes. Below 7000 feet the Danger is Moderate. Falling temperatures yesterday afternoon and last night have already begun re-freezing our very soggy snowpack. The possibility of human caused wet loose or wet slab avalanches will remain until the snowpack has completely refrozen. Avoid steep slopes until the lower snowpack refreezes. Considerable, 3: Dangerous avalanche conditions. Careful snowpack evaluation, cautious route- finding and conservative decision-making essential. Avalanche Problem 1: Wind Slab Our Avalanche problems have flip flopped over the last few days quite a bit but wind seems to be the constant factor in our snowpack this year. We found quite a few newly deposited wind slabs in mostly Northerly terrain yesterday but also saw evidence of loading and crossloading on E and W aspects as well. The areas that we inspected held shallow but brittle wind slab mostly on the highest ridgelines where there was enough new snow to begin forming them after the rainline crept up to over 8000ft. on Thursday. After the amount of wet avalanches that occurred during the storm, thin wind slabs seem like a relatively easy problem to manage. You are going to see a lot of avalanche debris if you are in the mountains today, as always, please send us your pictures or observations. Avalanche Problem 2: Loose Wet Our snowpack received a serious soaking over the last few days. Rain began Wednesday evening in the valley and the rainline rose to over 8000ft during the day on Thursday. Creeks raged, numerous natural wet loose slides occurred as well as a few large wet slabs. We covered a lot of ground yesterday and saw quite a few decent sized avalanches. We also found that the rain had saturated the snowpack over 3.5 feet down as nearly 2.5 inches of rain fell. In the upper elevations, there was already a supportable crust forming by mid afternoon. As the cold front cooled things down, the snowpack near 6500 feet was already forming a thin crust as well. Overnight temperatures dropped into the low teens and will have done a great job setting things up. If you are headed out today, bear in mind that it is still going to take a few days for the rest of the snowpack to refreeze. Avoid steep terrain especially if the snow surface feels punchy or you can penetrate through the surface crust. By tomorrow, our wet loose/slab instabilities will probably be gone. Day time warming is going to be the next weather factor to keep in mind. Temperatures during the day will be warming tomorrow through the early part of the week creating the potential for loose wet slides as temperatures climb. advisory discussion Warren Wagon snowmobile route is Closed right now. A creek between Fisher Creek and Deep Creek flash flooded/experienced a debris flow that has blocked the road with snow and woody debris as well as cutting a deep channel through the snowmobile route and is impassible. Acess to the Copet Creek Route is still open. The Brush Creek route is now open and should be groomed tonight. Lick Creek Road had water flowing across it yesterday afternoon as well near the Forest Boundary. CURRENT CONDITIONS Today's Weather Observations From the Granite Weather Station at 7700 ft.: 0600 temperature: 13 deg. F. Max. temperature in the last 24 hours: 30 deg. F. Average wind direction during the last 24 hours: W/SW Average wind speed during the last 24 hours: 6 mph Maximum wind gust in the last 24 hours: 18 mph New snowfall in the last 24 hours: 4.5 inches Total snow depth: 65 inches weather Colder and drier today through Sunday under northwest flow aloft behind exiting upper trough. Still enough clouds and moisture for a few snow showers in northern mountains today. Mostly clear tonight and Sunday excpt patchy fog in northern valleys and in Lower Treasure Valley. Light northwest winds today except moderate in south-central Idaho. Light and variable winds tonight, then light southeast Sunday. Snow level will be near valley floors through Sunday generally stopping snowmelt for the weekend. Temperature inversion will form in the Lower Treasure Valley with Sunday`s highs about 3 degs lower than today. Elsewhere, high temps Sunday will be much like today.