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Observation Date
4/16/2015
Observer Name
Bruce Tremper
Region
Salt Lake
Location Name or Route
Wasatch Range overview
Weather
Sky
Overcast
Wind Direction
Northeast
Wind Speed
Moderate
Weather Comments
It's mostly cloudy this morning with some clearing forecast by afternoon but enough low elevation moisture that there could be some greenhousing by afternoon.
Snow Characteristics
New Snow Depth
2.5'
New Snow Density
Low
Snow Surface Conditions
Powder
Snow Characteristics Comments

Amazing, old fashioned, Cottonwoods storm--the largest of the year--which ain't sayin' much in a year like this. Alta Collins weather station has an incredible 34 inches of storm snow as of this morning--almost 3 feet! Most other locations in the Cottonwood Canyons are around 2-2.5 feet. Snow is low density and I've seldom seen so many ecstatic powder hounds as I saw at Alta yesterday. Unfortunately I only had time to take one trip up the chair to talk with the ski patrol about their avalanche control results. The storm was confined mainly from about Farmington to Little Cottonwood Canyon--not much south or north of the classic lake effect band. The storm has ended and we have a northeasterly flow with a few very light snow showers lingering.

Remember all the south and west facing slopes were almost completely bare before this storm so the new snow only conceals the treacherous rocks lurking below. I took a lap to Pole Line Pass with the UDOT crew and they had memorized where the ribbons of pre-existing snow were and we followed them down, but I still clicked on a rock occasionally.

Red Flags
Red Flags
Recent Avalanches
Heavy Snowfall
Wind Loading
Cracking
Rapid Warming
Red Flags Comments
Yesterday, there was widespread soft slabs and wind slabs within the new snow sliding on some density inversions near the base of the new snow. Since it was so incredibly warm before the storm arrived, the old snow was damp in most places so the new snow bonded to it. But the new snow was so low density and the precipitation intensity was so high during the fist part of the storm, that it made slabs within the new snow on most slopes. Avalanches were sensitive and ran fast and far. The wind exacerbated the soft slabs.
Avalanche Problem #1
Problem
New Snow
Problem #1 Comments

The snow had time to settle overnight with diminished wind so I suspect that slides will be harder to trigger. But with so much new snow you have to remain suspicious. Even though it's very low density snow, 3 feet of it can really pack a punch. You should especially be suspicious of wind slabs in upper elevation wind exposed terrain.

Since I'm the only forecaster still working and we don't have a lot of information coming in, I don't want to use a danger rating. Most of the resorts are picking Moderate as the danger rating on our Infoex this morning, so that is what I've chosen on this observation.

Avalanche Problem #2
Problem
Wet Snow
Problem #2 Comments

In spring, you can almost always count on wet activity when the cold, dry snow gets damp or wet for the first time. It will start as rollerballs and then can escalate into sluffs and even wet slabs. The clouds this morning should clear by afternoon and there is enough low elevation moisture around to make some greenhousing as sun filters through the low clouds, which can shine heat on all aspects at the same time. So watch for that as things warm today and tomorrow.

Today's Observed Danger Rating
Moderate
Tomorrows Estimated Danger Rating
Moderate