Avalanche Advisory
Advisory: Ogden Area Mountains Issued by Evelyn Lees for Sunday - February 18, 2018 - 7:29am
bottom line

Increasing avalanche danger today through Monday in all the mountains of northern, central and southern Utah.

The avalanche danger in the Ogden area mountains is CONSIDERABLE today on all steep, wind drifted slopes, and is expected to rise to HIGH overnight and Monday during periods of heavy snowfall. Dangerous avalanche conditions exist – avalanches can also break into the deeper weak layers on northwest through easterly facing slopes. If you head into the backcountry, careful snowpack evaluation, cautious route finding and conservative decision-making are essential.
avalanche watch

* TIMING…THROUGH 6 AM MST MONDAY

* AFFECTED AREA…FOR THE ALL MOUNTAINS OF NORTHERN AND CENTRAL UTAH

* AVALANCHE DANGER…THE AVALANCHE DANGER FOR THE WARNING AREA IS CONSIDERABLE AND IS EXPECTED TO RISE TO HIGH OVERNIGHT.

* IMPACTS…STRONG WINDS TODAY WITH PERIODS OF HEAVY SNOW TONIGHT THROUGH TUESDAY WILL CREATE WIDESPREAD AREAS OF UNSTABLE SNOW. THE AVALANCHE DANGER WILL REMAIN ELEVATED THROUGH TUESDAY WITH BOTH HUMAN TRIGGERED AND NATURAL AVALANCHES BECOMING LIKELY. STAY OFF OF AND OUT FROM UNDER SLOPES STEEPER THAN 30 DEGREES.
special announcement

We are saddened to report that Orem resident Alexander Marra was killed in an avalanche yesterday in Wyoming. He was skiing out-of-bounds at JHMR, and triggered a 2-foot deep slide that took him over cliffs. Our thoughts and sympathies go out to his family and friends. Accident Report.

Episode 5 of the UAC podcast "To Hell in a Heartbeat - A Conversation With Tom Diegel and Matt Clevenger About the 12.26.08 Full Burial on Little Water" is live. Matt and Tom about the avalanche documented in To Hell in a Heartbeat. Check it out on ITunes, Stitcher, the UAC blog.
current conditions

After a calmer day than expected, the southwesterly winds finally picked up yesterday evening and have been blowing hard all night. The mid elevations have 15 to 20 mph averages with gusts in the 50s and 60s. On Mt Ogden, speeds are averaging 50 to 55 mph, with gusts in the 70s. Skies are overcast, and mountain temperatures very warm this morning – mostly in the mid 20s to 30s, with a few 40s at the lowest elevations.

recent activity

The only avalanche activity reported in the Ogden area mountains yesterday were a few isolated hard wind slabs under the upper elevation ridge lines and around terrain features. wind slab.

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

Wind drifts, known as wind slabs, will be much deeper and more widespread today and found at both the mid and upper elevations. Smooth, rounded, dense and cracky – they will be found along ridgelines and also well off the ridge lines, with drifts down in open bowls, along gully walls, and on mid slope break overs. Avoid wind drifts on steep slopes, which will be most widespread on the northerly through easterly facing slopes.

Cornices will have formed along ridgelines, and often break back further than expected. Give them a wide berth.

Natural avalanches are possible today - avoid traveling below steep wind drifted slopes.

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

We are overloading the faceted weak layers in our snowpack with the additional weight of wind slabs today and new snow tonight. On many slopes, these previously dormant mid and lower pack weak layers will now be easier to trigger. As they become more sensitive, they can be triggered from a distance, from below or by releasing a wind slab that then steps down.

Our snowpack depths are unusually variable, and the snowpack is especially weak where it is shallow, including slopes that have slid one or more times this year. Cracking and collapsing are bulls-eye clues to instability.

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

Heavy snowfall may start as early as noon in the Ogden area mountains. As the inches (and hopefully feet?) pile up today and tonight, storm snow slabs and sluffs can be triggered on steep slopes of all aspects, many running on the slick crusts beneath.
weather

Another warm and windy morning as we wait for the cold front to arrive. Increasing and lowering clouds all day. Temperatures will be in the 30s, until frontal passage, and the southwesterly winds strong - with 30 to 40 mph averages at mid elevations, and gusts in the 50s. The highest peaks will average to 55 mph, with gusts in the 60s and 70s.

An intense frontal passage is expected around noon in the Ogden area mountains, with a burst of heavy snowfall. Lightning is possible. About 4 to 8” of snow by sunset, with an additional 5 to 10" of snow overnight. Winds will shift to the northwest and decrease, and temperatures plummet into the single digits. Very cold Monday and Tuesday, with additional snow possible, and storm totals by Tuesday could be in the 16 to 28” range.

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.