Avalanche Advisory
Advisory: Provo Area Mountains Issued by Evelyn Lees for Monday - March 19, 2018 - 6:59am
bottom line

The avalanche danger is CONSIDERABLE – dangerous avalanche conditions exist in the upper elevations of the Provo area mountains. Human triggered avalanches are possible, so evaluate the snow and your choice of terrain carefully. These are the avalanche problems:

Deep slab avalanches: Large avalanches 2 to 5 feet deep can be triggered in isolated areas – steep slopes facing north through easterly with a shallower snowpack at the mid and upper elevations are the most suspect.

Wet loose sluffs: can be triggered on steeps slopes if the sun comes out or the snow heats where you are

Wind slabs and cornices: avoid the new wind drifts on steep slopes, which are more widespread than yesterday due to the overnight winds. Avoid travel on and below cornices.




special announcement

current conditions

Skies are partly cloudy this morning and temperatures dropped into the teens and lower 20s overnight, with cold single digits on the highest peaks. Scattered snow showers yesterday and overnight added another trace to 2” of snow in the mid to low elevations of the Provo area mountains. The winds remain from the northwest this morning, with mid stations averaging less than 5 mph. The highest peaks to the north are averaging only 15 - 20 mph. Of note – wind speeds were stronger overnight at the upper elevations – from the NW, with averages to 30 mph.

recent activity

No new observations from the Provo area mountains. Small to medium new snow slides were released with explosive control work in Little Cottonwood Canyon. No avalanches reported from the backcountry, though new wind slabs were cracking, but not moving far, and cornices sensitive.

But backing up just 2 days, there were 3 significant deep slab avalanches on Saturday in the Salt Lake area mountains.

Below: Saturday, March 17 – lower portion of a snowboarder triggered avalanche in a closed area on Millicent. Photo: Brighton Ski Patrol

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

Memo to self: it’s only been 2 days since 3 deep slab avalanches were triggered. Plenty of untracked powder on lower angle slopes.

With all the new snow this past week, with up to 2" of water it is still possible to trigger a deep avalanche breaking on a weak facet layer in the snowpack. While these deep slab avalanches are unpredictable and difficult to trigger, if you do, it will be very large and dangerous. Deep slab avalanches could be triggered by a person or a smaller slide - especially avoid steep, complex terrain with sharp break overs, rocks or cliffs and shallow snowpack areas, such as slopes that have already slid one or more times this year.

Avalanche Problem 2
type aspect/elevation characteristics
LIKELIHOOD
LIKELY
UNLIKELY
SIZE
LARGE
SMALL
TREND
INCREASING DANGER
SAME
DECREASING DANGER
over the next 12 hours
description

The sun and clouds will be playing cat and mouse today, with a mix of clearing, high thin clouds and mid level clouds.

If the snow starts to heat where you are – signs such as snow falling off trees, easily triggered roller balls, the surface snow becoming damp – it’s time to move to a cooler aspect or low angle terrain. Once you get a wet loose sluffs moving, it could entrain snow as it moves down slope, even gouging into the deeper rain soaked wet snow at the mid and lower elevations. Expect long running wet sluffs in the Provo area mountians due to the continuously steep terrain. Avoid even the small terrain traps like gullies and creek beds, where a little slide can pile debris up deeply

Avalanche Problem 3
type aspect/elevation characteristics
LIKELIHOOD
LIKELY
UNLIKELY
SIZE
LARGE
SMALL
TREND
INCREASING DANGER
SAME
DECREASING DANGER
over the next 24 hours
description

There will be new wind slabs at the upper elevations this morning, due to the stronger overnight northwesterly winds. The drifts will be most prevalent on southerly facing slopes, and more widespread than yesterday but look for drifting on all aspects. Cornices continue to be sensitive, so stay way back from the edges.

weather

March weather is like a yoyo – going up and down between winter and spring. We’re moving into spring today, with partly cloudy skies and temperatures warming into the mid to upper 20s at 9,000’. The northwesterly winds should remain light all day, 5 to 15 mph at the mid elevations, with the high peaks only averaging 10 to 20 mph. Warm and dry again on Tuesday, followed by a moist storm system arriving Wednesday. An unfortunately high rain/snow line is expected Wednesday and Thursday, but colder air arrives for the weekend, dropping the snow levels.

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.