In
partnership with: The Friends of the Utah Avalanche Center, Utah Department of
Public Safety Division of Comprehensive Emergency Management,
To have this advisory automatically e-mailed to you each day free of charge, visit: http://www.mailermailer.com/x?oid=16351h
For photos of avalanches and
avalanche phenomenon, visit: http://www.avalanche.org/%7Euac/photos_03-04.htm (Updated
3/25)
Photos sent in by observers
throughout the season visit: http://www.avalanche.org/~uac/obphotos/observer.html (Updated
4/2)
For a list of backcountry avalanche
activity, visit: http://www.avalanche.org/%7Euac/Avalanche_List.htm (Updated
3/31)
Early morning preliminary information by about 6:00 am: 801-364-1591
END OF SEASON BULLETIN
Monday, April 12, 2004
Good morning, this is Drew
Hardesty with the
This past winter came in like
a lion and went out like a lamb (hoping this will be tempting the gods). The Wasatch received over five hundred inches
of snow with upper Little Cottonwood monthly totals for Nov-125”, Dec-151”, Jan-74”,
Feb-130”, and Mar-62”. The silver lining
of a good early season and a marginal end, though, is that it effectively
eliminated the formation of depth hoar at the base of the snowpack, something
that plagued us in 2002-2003. Even Bruce
was bragging about not remembering the last time we’d had such good coverage
and stable snow by the end of November. So
throw in a couple rain events, a couple dust storms, a few avalanche cycles, the
obligatory January inversion and record breaking heat in March and you pretty
much have the gist of the season.
While we’ve issued our last
daily advisory for the year, this doesn’t mean there won’t be any more
avalanches. It just means that the money
has run out and most people would rather ride their bikes, work in the garden
and go climbing than go skiing, boarding or snow-machining. We’ll likely issue intermittent afternoon
information through the rest of the spring, but more likely, you’re on your
own, so here are some things to think about.
First,
there’s a wealth of information available on the internet at the usual
locations, such as the National Weather Service page (http://www.wrh.noaa.gov/Saltlake/). You can click on the Snow and Avalanche section to look at the automated mountain
weather stations. Unfortunately, many of
them will be shutting down soon, if they haven’t already, but Snowbird usually operates
through the spring. You can always check
the temperatures and snow amounts on the SNOTEL sites at (http://www.wrh.noaa.gov/Saltlake/avalanche/snotel/indexWorkArea.html)
and we also have a link from our web site at www.avalanche.org - click on Salt Lake then Snow and Weather.
Nowcasting
for the spring comes down to wet avalanches, avalanches associated with new
snow, and then glide avalanches. To
figure out whether or not the snow has frozen overnight, it’s not quite as
simple as just looking at the temperatures: you’ll need to gauge temperatures
with cloud cover and relative humidity. But
as a general rule with clear skies, if the overnight low in
Generally
speaking, wet slab avalanches occur
when a cold, dry snowpack first warms up to freezing and water begins to
percolate through the snowpack. This
occurs in early spring on south facing slopes, in mid spring on east and west
facing slopes and in late spring on upper elevation north facing slopes. They often happen after three nights where
the snowpack did not freeze combined with strong melting during the day. Another form of wet slab avalanche is a glide avalanche, which means the entire
snowpack slides slowly on the ground, kind of like a glacier until they release
catastrophically. These usually happen
on steep rock slabs such as in Broad’s Fork and Stairs Gulch (photos of these
can be found on our website). They can
happen any time of day and are most likely to occur during very warm conditions
and they can easily happen just after a freeze at the end of a warm
period.
Finally,
when the inevitable freak spring storms come, you’ll have to worry about the
usual round of new snow sluffs and soft slab avalanches just like in
mid-winter. As always, avoid steep
slopes with recent deposits of wind drifted snow and remember that when the sun
comes out, wet loose avalanches occur like clockwork. Most every spring, there are several close
calls at the resorts that are closed for the season. People are used to those slopes being safe
because the ski patrol does avalanche control, but by spring, you’ll have to
treat this terrain just like any other backcountry location.
Backcountry
snow and avalanche information is still useful to us. So if you’re still getting out and see
anything of interest, leave us a message at 524-5304, 1 800-662-4140, drop us
an email at [email protected], or a fax
to 524-6301. Bruce, Evelyn, Andrew,
Craig, and I want to thank our Friends, observers and supporters for another
great season. We couldn’t do it without
your help. See you next fall.
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