Salt Lake Avalanche Advisory

Forecaster: Evelyn Lees

SPECIAL ANNOUNCEMENT

We are doing intermittent avalanche advisories, and this forecast covers the weekend of April 21st and 22nd.


BOTTOM LINE

Danger by aspect and elevation on slopes approaching 35° or steeper.
(click HERE for tomorrow's danger rating)


Danger Rose Tutorial

The avalanche danger will be low early Saturday morning, with a possible shallow refreeze. It will rapidly rise to MODERATE on Saturday with sun and day time heating, for wet loose sluff avalanches at all elevations and on all aspects with remaining snow. Both natural and human triggered avalanches are possible, with mid and upper elevation northerly facing slopes having the greatest slab avalanche potential. The avalanche danger will continue to rise through the weekend and into early next week, and the danger may rise to CONSIDERABLE, with wet slab avalanches are possible.


CURRENT CONDITIONS

The heat wave has started, with temperatures already above freezing at almost all elevations this evening. Today’s heat dampened the snow even on the upper northerly facing slopes, with the snow downright wet on all other slopes.


RECENT ACTIVITY

With partly cloudy skies and light rain and snow, the past few day’s avalanche activity has been mostly limited to wet loose sluffs, both natural and human triggered, on all aspects. We will continue to update ourCurrent Conditions page, and appreciate any observations.


THREAT #1

WHERE PROBABILITY SIZE TREND
      Over the next 24 hours.

The big heat up is here, and this latest assault on the snowpack could bring a widespread round of wet avalanches this weekend into early next week. The heat has some snow to work with – as much as 12 to 18 inches of settled dense snow on the highest, northerly facing slopes, with a few buried crusts to act as sliding surfaces and the winter’s nemesis of lingering faceted layers. While wet sluffs will be the most common heat related avalanche, more dangerous wet slab avalanches are possible the next few days.

There are numerous red flags to watch for and clues that let you know it’s time to leave the backcountry, or at least stay off of and out from under steep slopes.

· Radically, above freezing temperatures with strong sun.

· Non-freezing nights, especially two or three in a row.

· When the snow surface becomes wet and sloppy.

· Roller balls wheeling down slopes, mostly on mid and upper elevation shady slopes.

· “Bending” of the surface slab as you move across, indicating the slab over a weak layer is barely strong enough to hold your weight.

· Glide cracks – avoid travel below.

· Structure – any layers in the snow pack, from ice crusts to wet facets, add to a weaker snowpack.

The classic spring time routine of very early starts and early finishes will help for Saturday.

Keep in mind that in isolated places, a triggered sluff might gouge into wet snow or trigger a slab avalanche.


THREAT #2

WHERE PROBABILITY SIZE TREND
      Over the next 24 hours.

The combination of new snow and wind the past week has created a fresh batch of cornices, which will become increasingly sensitive with heating. Give them a wide berth from above, and avoid traveling and hanging out below.


MOUNTAIN WEATHER

A strong high pressure ridge has moved over Utah and will remain through Tuesday, giving us another round of “high speed melting”. Temperatures will soar, with 8000’ highs near 60 on Saturday, and into the 70s Sunday through Tuesday. 10,000’ temperatures will warm into the mid 40s on Saturday and into the low 50s by Monday and Tuesday. Skies will be mostly clear Saturday and Sunday, forecast to become partly cloudy starting Sunday night.

Be sure to monitor the National Weather Service for the current weather forecast and monitor the Snow Page for current weather conditions.


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.


This advisory provided by the USDA Forest Service, in partnership with:

The Friends of the Utah Avalanche Center, Utah Division of State Parks and Recreation, Utah Division of Emergency Management, Salt Lake County, Salt Lake Unified Fire Authority and the friends of the La Sal Avalanche Center. See our Sponsors Page for a complete list.