Avalanche Advisory
Advisory: Skyline Area Mountains Issued by Brett Kobernik for Saturday - March 4, 2017 - 6:33am
bottom line

The overall avalanche danger is generally LOW. A MODERATE danger exists along the higher more easterly facing steep slopes where a person still might trigger a lingering wind drifts. Cornices are large right now also and often become weak during warmer weather like today. Also, move off steep slopes and stay out of confined steep walled gullies as the snow becomes wet with daytime heating.
current conditions

Overnight temperatures dropped into the low 20s and southerly wind is light to moderate in speed but is hinting at increasing in speed. Very warm temperatures on Friday heated the snow surface on all but the higher more northerly facing slopes. Check out Darce Trotter and Steve Cote's backcountry observations from Friday HERE.

WEEK IN REVIEW: Weather, Snow and Avalanches.

The week started off with an intense cold snow storm that laid down 15 inches of new snow on Monday. The snow was falling very rapidly toward the end of the storm with snowfall rates up to 3 inches an hour. This caused some instabilities within the new snow which was evident in areas where you could see that the slope had "spiderwebbed" with cracks. This was a shallow instability near the surface and didn't produce large avalanches. However, the wind did increase on Tuesday and drifted the new snow creating large drifts, cornices and fresh wind slabs. Consequently, the wind drifted enough snow to overload some slopes and make them avalanche.

Date Region Place Trigger Depth Width Aspect Elevation Weakness
02/28/2017 Skyline Bulger Canyon Natural Northeast 11000 Density Change Details
02/28/2017 Skyline Potters Natural Northeast 10600 Density Change Details

As the week progressed, these drifts and wind slabs became more stable and harder to trigger. Most people found excellent deep powder riding conditions all week. Temperatures gradually warmed through the end of the week making the snow surface damp on many aspects and all lower elevations.
recent activity

Snowmobilers triggered a few avalanches along the upper ridgelines when they were riding out of Ephraim Canyon on Friday. These were very steep slopes where the wind had deposited snow earlier in the week. Solar heating may have also played a role in loosening the wind slabs making them more sensitive and easier to trigger.

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

You will want to anticipate the chance for triggering a wind slab along the higher more east facing steep slopes again today. The majority of these drifts that formed earlier this weak are stubborn and locked in place. However, yesterday's snowmobile triggered slides show that there are still places where they are sensitive.
Avalanche Problem 2
type aspect/elevation characteristics
LIKELIHOOD
LIKELY
UNLIKELY
SIZE
LARGE
SMALL
TREND
INCREASING DANGER
SAME
DECREASING DANGER
over the next 10 hours
description

Daytime heating may create some wet avalanche activity on the sunny facing slopes. Avoid being on and below very steep slopes as the snow becomes wet during the day.
weather

Today will be the warmest day of the week with ridgetop temperatures in the mid to upper 40s. Southerly winds will increase in speed and be a bit gusty along the higher terrain. Sunday looks like another nice day although a bit breezy. We'll see another intense cold snow storm move through Sunday night into Monday with temperatures down into the teens and single digits and perhaps 10 inches of new snow.
general announcements

We will publish full detailed advisories Saturday and Sunday mornings by 7am. We will also be publishing basic avalanche danger ratings & info during the week.

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