Avalanche Advisory
Advisory: Ogden Area Mountains Issued by Mark Staples for Saturday - April 14, 2018 - 7:22am
bottom line

Because the old snow underneath is hard and frozen, avalanche issues exist only in the 13 inches of new snow.

First, watch for wind slabs at the upper elevations where the avalanche danger is MODERATE. Many wind slabs should be well bonded this morning but there are probably some that can still be triggered.

Second, as the day warms, the new snow on slopes receiving direct sunshine should become wet and produce some wet loose avalanches. The avalanche danger on these slopes at mid and upper elevations is MODERATE as well.

Slopes that do not have wind-blown snow and are not getting wet from warming have a LOW danger.
special announcement
The last regular avalanche forecast will be tomorow, Sunday April 15. After that, we will issue intermittent advisories for the Salt Lake mountains through the end of April with each snowfall. We will continue to post all observations so please keep sending those in.
current conditions

Under clear skies this morning temperatures dropped into the mid 20's F. Westerly winds are blowing 5-15 mph with gusts of 25 mph.

Snowfall started Thursday morning and continued through yesterday afternoon with the area near Snowbasin receiving 13 inches of snow.
recent activity

Ski patrollers were able to trigger just a few soft slabs yesterday with explosives.
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

Winds have been blowing from the NW and transporting the new snow. The strongest winds occurred Thursday evening when they were blowing 30-50 mph. Winds at ridgetops continued to transport some snow yesterday. Many wind slabs and drifts should be well bonded today.

Regardless of this bonding, some wind slabs could be triggered. The higher you go in elevation, the more likely it will be that you can find one. The best option is to avoid wind slabs which is doable because you can identify them by their smooth and rounded appearance. Wind slabs can also be identified by their location which is typically under cornices or along cross-loaded gullies. Another higher risk option is to ski cut them before entering a slope.

Heads up - While not an avalanche issue, watch for isolated places where recent winds stripped the new snow off the underlying ice crust.
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

Th strong April sun will quickly warm slopes receiving direct sunshine. With a cold start to the day and some clouds expected in the sky, it's hard to know how quickly and how wet the new snow will become by this afternoon.

The good news is that this avalanche problem is predictable. When the snow becomes wet, you'll know it because the riding conditions will deteriorate. Additionally, you'll likely see pinwheels and rollerballs of snow tumbling downhill. As this happens the danger of loose wet snow avalanches will increase. The hard ice crust underneath will make it easier for these slides to run far if it becomes wet down to this ice layer.

A good strategy this time of year is to slowly change aspects through the day. If starting this morning, begin on slopes receiving direct sun. As the snow on these slopes warms move to shaded or northerly facing slopes which should harbor colder and drier snow.
weather

Today will have a mix of clouds and sunshine. I'm not sure which we'll see more of, but it doesn't take much sunshine this time of year to quickly warm up the air and the snow. High temperatures at 9000 feet should climb into the mid to uppper 30's F but could feel warmer in the sun. Winds will shift from the NW to W and ease. They will be blowing 5-10 mph and up to 20 mph at the highest elevations.

Looking ahead, winds will shift to the SW on Sunday and bring much warmer temperatures. By Sunday evening and Monday morning, winds will increase substantially from the SW. However a cold front will arrive Monday evening and drop temperatures into the teens F. Snowfall should arrive with this cold front and possibly deliver 6-8 inches of snow by late Tuesday.
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.