In partnership with: The Friends of the Utah Avalanche Forecast Center, Utah Department of Public Safety Division of Comprehensive Emergency Management, Salt Lake County, and Utah State Parks
Tuesday, February 18, 2003
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Good Morning. This is Bruce Tremper with the
Temperatures are cold again this morning with ridge top temperatures around 10 degrees with a 20 mph wind from the west, gusting to 30 on the exposed peaks. Two days ago we had a violent little graupel storm. Graupel is that kind of Styrofoam ball snow and 6-8 inches fell in the Cottonwood Canyons with half that amount elsewhere. Yesterday, the south facing slopes got sun crusted but there’s still nice, soft dry snow on the slopes facing the north half of the compass.
We heard about a couple backcountry avalanches from yesterday. First, some snow boarders went out of bounds from Brighton and the third boarder down the west side of Millicent Peak triggered a soft slab avalanche about 100 feet wide and 1- 2 1/2 feet deep on a 38 degree slope, which ran about 300 vertical feet. Luckily, the boarder had his speed built up and was able to outrun the slide. It broke below the rain crust from February 13th and the boarder triggered it from the deepest part of the fracture, probably in a pool of graupel that rolled off the cliffs. The second avalanche occurred in the backcountry on the east side of Clayton Peak near Brighton, which was triggered remotely by explosive avalanche control at Brighton. It broke 3-4 feet deep, 100 feet wide and broke into deeper layers of faceted snow.
Today, we’re worried about two different avalanche problems:
First, you may be able to
trigger some localized avalanches within the new snow. For instance, the graupel snow which fell on
Sunday tends to roll off of cliffs and steep slopes and pool on the flatter
aprons underneath steep slopes. So you
should continue to wa
Second, is our old problem,
the weak layers of faceted snow and depth hoar near the ground, which formed
during clear weather in December and January. We have had a coupe inches of water weight
added over the past week and this is enough to stress some of these deeper weak
layers enough to make them sensitive to human triggers. We’ve had three different avalanches break
into these deeper weak layers in the past three days including the fatal
Gobbler’s Knob avalanche on Saturday, Wolverine Cirque on Sunday and the east
side of Clayton Peak yesterday.
Both of these avalanche problems are quite localized, meaning that you could trigger an avalanche only on a small percentage of the terrain, but especially with the deeper avalanches, the consequences can be quite severe, as we discovered with the Gobbler’s Knob avalanche on Saturday.
Bottom Line (SLC,
There is also a MODERATE (or localized) danger of triggering an avalanche within the new snow from recent wind drifting or graupel pooling beneath cliffs. There is also a MODERATE danger of triggering an avalanche on deeper weak layers of old, faceted snow on slopes that face the north half of the compass, plus east facing slopes, steeper than about 35 degrees and above about 9,000 feet, especially in thin, rocky areas.
Today we have a weak system
of unstable air coming into Utah this afternoon and tonight, which could give
us some scattered, light snow showers and probably not add up to more than 2-4
inches. Ridge top temperatures will warm
up to around 15 degrees today with a west wind around 15 mph and blow around 25
mph tonight, swi
To report backcountry snow and avalanche conditions, especially if you observe or trigger an avalanche, remember that the information you have could save someone’s life. Please leave a message on our answer machine at (801) 524-5304 or 1-800-662-4140, or email to [email protected] or fax to 801-524-6301. The information in this advisory is from the U.S. Forest Service, which is solely responsible for its content. This advisory describes general avalanche conditions and local variations always occur.
Evelyn Lees will update this advisory by on Wednesday morning.
Thanks for calling!
For an explanation of avalanche danger ratings: