Avalanche Advisory
Advisory: Provo Area Mountains Issued by Mark Staples for Monday - February 19, 2018 - 7:23am
bottom line

The avalanche danger is HIGH at upper elevations and CONSIDERABLE at mid elevations. Storm slab avalanches are very likely and travel in avalanche terrain is not recommended. Winds may increase later today from the NW and exacerbate this problem. Additionally this load of new snow will stress deeper layers of snow and persistent slab avalanches are likely at mid and upper elevations on NW, N and NE facing slopes.
special announcement

Episode 5 of the UAC podcast "To Hell in a Heartbeat - A Conversation With Tom Diegel and Matt Clevenger About the 12.26.08 Full Burial on Little Water" is live. Matt and Tom about the avalanche documented in To Hell in a Heartbeat. Check it out on ITunes, Stitcher, the UAC blog.
current conditions

Welcome back winter! This morning 9-12 inches of snow fell. It’s relatively calm and cold. This morning winds shifted to the NW and were blowing 5-10 mph gusting 10-15 mph. Temperatures are mostly in teens F and single digits above 10,000 feet.
recent activity

In Little Cottonwood Canyon, at least a dozen natural avalanches occurred on the north side road from 9 p.m. and 2 a.m. during intense snowfall. These probably only involved the new snow. Avalanches likely occurred in many other places during that time but we don't know about them yet. No avalanches were reported yesterday during the day.

On Saturday, many natural avalanches were spotted along Cascade Ridge like ones in the photo below (S. Archer). Other avalanches were spotted on Cascade Mountain following Thursday's storm.
Avalanche Problem 1
type aspect/elevation characteristics
LIKELIHOOD
LIKELY
UNLIKELY
SIZE
LARGE
SMALL
TREND
INCREASING DANGER
SAME
DECREASING DANGER
over the next 24 hours
description

Storm slab avalanches are likely and travel in avalanche terrain is not recommended. The surest sign of unstable conditions is recent avalanche activity which happened overnight and early this morning. Additionally, dry loose avalanches are likely with such light snow.

Later today winds could start to increase from the NW. They will easily transport today’s light snow and wind slabs could become a problem as well. Even if winds don't make big obvious wind slabs, they could transport just enough snow to keep storm slab avalanches likely.

Widespread avalanche activity following Thursday's storm is a good clue that many avalanches will occur today.
Avalanche Problem 2
type aspect/elevation characteristics
LIKELIHOOD
LIKELY
UNLIKELY
SIZE
LARGE
SMALL
TREND
INCREASING DANGER
SAME
DECREASING DANGER
over the next 24 hours
description

I am very nervous about avalanches breaking deeper in the snowpack on NW, N and NE facing slopes. The combined loading from today's snowfall with Thursday's snowfall will be too much for the snowpack to support. Additionally, strong SW winds on Saturday provided additional loading to slopes with wind drifting.

Overall, there is a lot of uncertainty with how the snowpack will react to this loading and which slopes will avalanche and which will not. We'll learn more in the next few days.
weather

On and off snowfall today should bring another 3-6 inches of very low density snow. Winds may increase from the NW later today and blow 10-20 mph. Temperatures will remain cold and may only rise a few degrees from where they are this morning. Tonight temperatures will get even colder and should drop below 0 F. Snowfall should be over by Tuesday and mountain temperatures may not rise above the single digits F. Temperatures will remain cold only be slightly warmer for most of the week.
general announcements

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This information does not apply to developed ski areas or highways where avalanche control is normally done. This advisory is from the U.S.D.A. Forest Service, which is solely responsible for its content. This advisory describes general avalanche conditions and local variations always occur.