Forecast for the Provo Area Mountains

Drew Hardesty
Issued by Drew Hardesty for
Monday, March 11, 2019
Many slopes still have a CONSIDERABLE danger at the mid and upper elevations. New snow avalanches from the recent storm can be triggered 1-2' deep on steep slopes. It's also possible to trigger a much larger and deeper slide that breaks into deeper weak layers on aspects facing northwest through north through southeast at the mid and upper elevations. With any extended sun and heating today, the danger on the steep sunlit slopes will rise accordingly.
Safe and excellent powder riding can be found on low angle northerly slopes with no overhead hazard.
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Moderate
Considerable
High
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Weather and Snow
Skies are partly cloudy with temps in the upper teens to low 20s. The southeasterlies gusted into the teens and low twenties for a couple hours overnight but all stations are currently showing light wind.
Skiing and riding conditions remain excellent although some sunny aspects have a breakable melt-freeze crust beneath a few inches of snow.
For today, we should have varying degrees of cloud cover with light easterly winds. Mountain temperatures will rise to 20°F along the ridgelines with many base areas and trailheads pushing into the mid-30s. Clearing tonight and tomorrow ahead of a sharp cold front for Tuesday night into Wednesday. I think we can bank on 3-6", perhaps a touch more by late Wednesday. It'll be full-on spring conditions with a ridge of high pressure building for Friday into next week.
Recent Avalanches
Friday afternoon we went through a widespread new snow avalanche cycle around 3:00 pm as the snowfall intensity increased. Numerous slide paths ran naturally with impressive debris piles noted off Timpanogos and in runout zones in Dry Creek above the town of Lehi (pic below). I would suspect many repeater avalanche paths ran with the storm leaving large avalanches and debris piles in their wake. These slides are powerful and in some cases have pulled and eroded large areas of rock along the track (see UDOT Provo pic below)
Thanks to Joe Martel with his excellent report here -
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Avalanche Problem #1
New Snow
Type
Location
Likelihood
Size
Description
You can still trigger an avalanche within the recent storm snow on a variety of structural interfaces up to and over two feet deep today. Failure planes may include graupel, early storm low density snow, and on sun and rain crusts. Absent the tell-tale signs of instability (cracking, collapsing), it's worth pulling out the shovel and performing a few snow tests to gather info on the snow that you're keen to ski or ride. Use test slopes (steep but low consequence terrain) to help gather info for representative terrain.
A couple of fine points for today:
Graupel (pellet snow) can be a significant weak layer as it often runs downhill and pools at the base of cliff bands or on clear transitions from steep to less steep terrain. It's not uncommon to successfully descend a couloir only to trigger the pocket in the aprons or more benign terrain below.
Sluffing today is possible in the steepest terrain and may be more likely and problematic on the steep southerly aspects today. Weak snow may have developed above yesterday's sun crusts and this may aid and abet any of the sluffing on these slopes.
Cornices are generally too large to tangle with and remain highly suspect. Remember 5% of our avalanche fatalities involve cornice fall.
Avalanche Problem #2
Persistent Weak Layer
Type
Location
Likelihood
Size
Description
I suspect many avalanches stepped down into older weaker layers leftover from previous avalanche events from January and March. These may have been many feet deep and hundreds of feet wide and most likely on northwest to northeast to southeast facing slopes at the mid and upper elevations. As one can see from the photos, these avalanches have - and can still - run quite far even into assumed safe terrain. The Provo snowpack remains dangerous on many aspects and elevations. Even very experienced people are giving a wide buffer of margin in this terrain. These are difficult and dangerous conditions to assess - from Cascade to Box Elder to Timp to the southern Wasatch Back (Snake Creek to Mill Canyon Peak).
Avalanche Problem #3
Wet Snow
Type
Location
Likelihood
Size
Description
Ah, spring. Where cloud cover and weather can turn on a dime. With significant sun and/or greenhousing, wet loose avalanches may be expected. This sort of thing can be hard to forecast, but easy to nowcast: if you're feeling hot and/or damp and humid, the snow feels the same - look for rollerballs, natural wet sluffs, and unsupportable snow.
KEY POINT: cold dry snow that sees sun/heating for the first time is almost always unstable in the spring - pay attention to what's going on around you.
General Announcements
This information does not apply to developed ski areas or highways where avalanche control is normally done. This forecast is from the U.S.D.A. Forest Service, which is solely responsible for its content. This forecast describes general avalanche conditions and local variations always occur.