Avalanche Advisory
Advisory: Provo Area Mountains Issued by Mark Staples for Wednesday - April 4, 2018 - 6:54am
bottom line

With a deep slab avalanche problem lurking on upper elevation, northerly and easterly facing slopes, the avalanche danger in these locations is MODERATE. All other slopes have a LOW danger. Avalanches that occurred last Wednesday show that this deep slab problem is still an issue in the Provo area mountains. These slides can break 2-5 feet deep and up to hundreds of feet wide. Also watch for and avoid any fresh wind drifts and wind slabs. These are much less of a hazard but worth looking for.

Hard, icy conditions also exist. While not an avalanche hazard, these "slide for life" conditions add an additional hazard in very steep terrain.




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current conditions

Temperatures this morning are mostly in the low 30's F, a huge change from yesterday when temperatures started in the teens single digits. Winds have increased since yesterday and are blowing westerly 15-20 mph gusting 30 mph. Gusts at 11,000 feet are up to 50 mph. A few inches of snow that fell Monday rest on mostly hard icy snow. The hard icy snow is as much of a hazard as any avalanche issue.

recent activity

No avalanche activity was reported yesterday.

There was an impressive avalanche cycle that occurred last week on Timpanogos. The snowpack in the Provo area mountains is very different and more dangerous that in the mountains just a little further north. Read the full observation HERE. Below is a list of some of these slides and a photo (J. Woodruff) of the debris pile from one of them.

  • Emerald Lake Headwall (Timp Glacier) 800' wide by 3'-5' deep. 11200' down to 10600' (600' vertical foot fall).
  • Below the summit shack on the NE face. (wind slab). 60' wide by 2' deep. 11200' down to 10400' (800' vertical foot fall.)
  • Timp Basin Ridge just north of the summer trail. 500' wide by 6'-9' deep. 11000' down to 10800' (300' vertical foot fall)
  • The largest slide and thanks to the pictures from Turly (Found HERE) we were able to determine that the entire slope to the north of the natural that he photographed including wrapping into Stairmaster bowl had avalanched. 11200' down to possibly 8500' (2700' vertical foot fall with a substantial debris pile)

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

The snowpack in the Provo area mountains is generally more dangerous than other areas further north. This area received less snowfall in the early months of winter, making it more shallow and weaker. Unfortunately many of those weak, faceted layers of snow remain at the upper elevation, northerly facing slopes. All it took to cause last week's avalanche cycle was strong winds. There are two layers of concern in the snowpack:

  1. One is faceted snow buried just underneath the February 18th dust layer. It's easy to find - dig down 2.5' in the snowpack and identify a dirty stripe of snow, just below that is a layer of weak faceted snow.
  2. The other is just above the ground - we call it depth hoar, which is a fancy name for larger grained faceted snow. In either case the avalanche you trigger would likely be unsurvivable.

It's best to avoid any and all steep northerly facing terrain. If going to ski some of the Peaks in the Provo area, it will be best to ski slopes that face a little more southerly. Go to these slopes after a few melt/freeze cycles and hopefully enjoy some stable corn skiing. In the near term

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

Aside from deeper and larger avalanches. Watch for fresh wind drifts and wind slabs. These are much easier to deal with becuase you can see where they exist. Look for smooth rounded snow as evidence of a fresh wind drift or wind slab. Most of these wind slabs should be small and shallow. However a few deeper and larger ones can be found. UDOT forecasters spotted one on Monday that was 2 feet deep and 60 feet wide.

weather

Today's skies will be mostly cloudy and there is a chance for a couple snowflakes to fall. Temperatures should warm into the mid-30's F and maybe even warmer. Winds will average about 15 mph with 25 mph gusts from the WSW. There is a decent storm brewing. Right now weather models are showing this storm occuring Saturday afternoon into Sunday morning. Snow levels for that storm should start near 9000 feet. It is a fast moving storm that won't linger over the area very long, but could deliver about an inch of snow water equivalent. It's hard to say how much snow that will be.

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.