Advisory: Salt Lake Area Mountains | utahavalanchecenter.org

Avalanche Advisory

Advisory: Salt Lake Area Mountains	Issued by Greg Gagne for Friday - March 30, 2018 - 4:54am

bottom line

The current avalanche hazard is generally LOW. But risks in mountain travel are always present. Don't let your guard down for wet loose avalanches on sunny aspects as the day warms, as well as pockets of recent wind-drifted snow at the mid and upper elevations. Although very unlikely, deep slab avalanches remain a concern in very isolated terrain such as thinner snowpack areas.

special announcement

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The UAC Marketplace is still open. Our online marketplace still has deals on skis, packs, airbag packs, beacons, snowshoes, soft goods and much more.

current conditions

Under partly cloudy skies and a setting full moon, 6 am mountain temperatures range throughout the 20's and winds are out of the west/northwest. At mid elevations winds are less than 10 mph with gusts in the teens, with gusts into the 20's mph at the upper elevations.

Last Thursday's rain event left behind a slick 2-6" thick rain crust that is now covered with pockets of wind drifts, sastrugi, and even patches of soft-ish/dry snow. Winds on Wednesday and into Thursday morning created widespread wind-affected snow in exposed mid and upper elevation terrain, and clearing skies yesterday afternoon left behind sun and temperature crusts on south and west aspects, and all around the compass at lower elevations. That said, if you search you can still find dry, chalky snow on northerly aspects at the mid and upper elevations, such as what UAC pro observer, the intrepid Mark White, found yesterday.

Our Week in Review summarizes weather and avalanche activity over the past week:

With no snow in the forecast, we can safely report March snow and water numbers from the fabled Alta Guard Station. Thanks to UDOT avalanche forecaster Mark Sauer for these numbers:

>> 70.5" of snow and 8.21" of water, with the 3/22 rain event with over 2" of water explains the higher water numbers. (74 year average is 86.6" and 7.93")

>> Year-to-date is 245" snow with 24.65" water. Average is 418" with 38.49." If we compare to our two worst years on record, YTD through March 2014-15 was 227" with 22.9" and 1976-77 was 284" with 21.82" water. IF we meet our April average of 66.5" we'll end up with 312" snow. This will beat 2014-15 (274") but fall behind 1976-77 (314").

recent activity

No backcountry avalanche activity was reported from Thursday other than minor wet loose activity on steep solar aspects.

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 avalanche hazard is generally Low and avalanches are unlikely. But travel in avalanche terrain is never a completely safe game, so watch for the following issues on isolated features: Loose Wet Avalanches - Today's forecasted winds, party cloudy skies, and still generally cool temperatures should keep wet activity in check, and I am expecting at most minor wet loose activity on solar (primarily south and west) aspects as the snow surface warms. But, if forecasted temperatures are warmer or winds are lesser or skies are clearer, wet activity may be more widespread. Clues such as wet rollerballs are obvious signs of instability. Wind Drifts - Yesterday my partner Bob Frey and I did our best to pry out drifts from Wednesday's winds (link to our observation), but we had no luck as the wind-drifted snow was unresponsive to ski cuts or other stability tests. However, there was a skier-triggered wind slab from Wednesday, and a rogue wind drift at the mid and upper elevations may still be found that is sensitive to the weight of a rider. Persistent Deep Slab - For the first time since mid-December, we are dropping persistent slab/deep slab as an avalanche problem. This doesn't mean the issue has gone away. Rather, it is currently dormant and avalanching on these deeper layers is very unlikely. That is, dormant and unlikely until things change such as a substantial new load or rapid warming. For the time being, last Thursday's rain event has created a strong bridge over these deeper weak layers, and they continue to adjust and strengthen. UAC director Mark Staples provides an excellent video summary of the current state of the snowpack: Additionally, full depth glide releases must be considered if you choose to travel in the Big Cottonwood drainages of Stairs, Broads, and Mill B South. To get a sense of these absolutely unmanageable avalanches, check out Mark White's recent observation from Broads Fork. And finally, although I may be a wet blanket over this beautiful green rose, the 2-6" thick impenetrable 3/22 rain crust may create slide-for-life conditions on steep aspects. Consider taking ski crampons, ice axe, and/or whippet if you choose to travel in steeper terrain. Otherwise we have a generally stable, modestly-deep snowpack providing excellent travel conditions for touring in the alpine zones.

type

aspect/elevation

characteristics

LIKELIHOOD

LIKELY

UNLIKELY

SIZE

LARGE

SMALL

TREND

INCREASING DANGER

SAME

DECREASING DANGER

over the next 24 hours

description

The avalanche hazard is generally Low and avalanches are unlikely. But travel in avalanche terrain is never a completely safe game, so watch for the following issues on isolated features:

Loose Wet Avalanches - Today's forecasted winds, party cloudy skies, and still generally cool temperatures should keep wet activity in check, and I am expecting at most minor wet loose activity on solar (primarily south and west) aspects as the snow surface warms. But, if forecasted temperatures are warmer or winds are lesser or skies are clearer, wet activity may be more widespread. Clues such as wet rollerballs are obvious signs of instability.

Wind Drifts - Yesterday my partner Bob Frey and I did our best to pry out drifts from Wednesday's winds (link to our observation), but we had no luck as the wind-drifted snow was unresponsive to ski cuts or other stability tests. However, there was a skier-triggered wind slab from Wednesday, and a rogue wind drift at the mid and upper elevations may still be found that is sensitive to the weight of a rider.

Persistent Deep Slab - For the first time since mid-December, we are dropping persistent slab/deep slab as an avalanche problem. This doesn't mean the issue has gone away. Rather, it is currently dormant and avalanching on these deeper layers is very unlikely. That is, dormant and unlikely until things change such as a substantial new load or rapid warming. For the time being, last Thursday's rain event has created a strong bridge over these deeper weak layers, and they continue to adjust and strengthen. UAC director Mark Staples provides an excellent video summary of the current state of the snowpack:

Additionally, full depth glide releases must be considered if you choose to travel in the Big Cottonwood drainages of Stairs, Broads, and Mill B South. To get a sense of these absolutely unmanageable avalanches, check out Mark White's recent observation from Broads Fork.

And finally, although I may be a wet blanket over this beautiful green rose, the 2-6" thick impenetrable 3/22 rain crust may create slide-for-life conditions on steep aspects. Consider taking ski crampons, ice axe, and/or whippet if you choose to travel in steeper terrain.

Otherwise we have a generally stable, modestly-deep snowpack providing excellent travel conditions for touring in the alpine zones.

weather

For today we'll have partly cloudy skies with 8000' and 10,000' temps rising into the low-40s and low-30s, respectively. Winds will be out of the west/northwest, averaging in the teens at mid elevations, and in the 20's mph at upper elevations (into the 30's mph as you approach 11,000'). Winds are forecasted to increase as the day progresses, especially into the overnight hours.

A weak system moves in on Saturday with increasing clouds and warmer temperatures, but unfortunately with no accompanying precipitation. Although we have no significant storms forecasted over the next 7 days, the models are also not suggesting winter is over.

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.

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