Wasatch Cache National Forest
In partnership with: Utah Division of State Parks and Recreation, The Friends of the Utah Avalanche Center, Utah Department of Emergency Services and Homeland Security and Salt Lake County.

“keeping you on top”

AVALANCHE ADVISORY

Friday, April 11, 2008 7:30 am
Good morning, this is Bruce Tremper with the Forest Service Utah Avalanche Center with your backcountry avalanche and mountain weather advisory. Today is Friday, April 11, 2008 and it’s about 7:30 am.

Special Announcement: We are expecting a strong warm up for the weekend. Very warm temperatures will cause widespread wet avalanche activity on most aspects and elevations especially on Sunday and Monday.

We will end our morning advisories after the weekend and issue only intermittent afternoon updates until the end of April. Yahoo! No more 3:00 am alarm clocks for us until November.

Current Conditions:

Riding conditions were euphoric yesterday on slopes that faced the north half of the compass with 10-20 inches of soft, dry powder mixed with graupel and cold temperatures. Unfortunately all areas outside of the Salt Lake area mountains had much less new snow over the past several days. The cold, north winds continued to blow yesterday, especially at upper elevations. There was enough clouds and cold temperatures to limit sun crusting and damp snow to the southerly facing slopes below about 9,000’.

Snow and Avalanche Discussion:

I heard reports of nearly a dozen different human triggered avalanches yesterday from the backcountry. Most all were soft, wind slabs from the strong north and northwest winds yesterday and the day before and most were in upper elevation, alpine terrain, 6 inches to a foot deep, 10-70 feet wide. Luckily they were what we sometimes call “manageable” meaning they were soft and shallow enough to break at your feet instead of above you, but one person on a very steep, east facing slope in Broad’s Fork had to grab a tree when they were caught. There’s too many to list here but you can find details on the early morning report 888-999-4019 option 8, or on our avalanche list (updated later this morning). Plus a photo of a natural in Broad’s Fork.

The main problem was that the riding conditions were so excellent yesterday that people were probably lured by euphoria and ignored the telltale signs of wind slabs—smooth, rounded shape and slabby feel. Also, several people reported collapses and whoomphing causing one very experienced party to wisely back off of a slope. This usually means that there is some kind of monkey business buried in the snowpack—probably a thin layer of faceted snow above the old, hard, melt-freeze layer, now buried 1-3 feet deep. Several people, me included, noticed some in localized areas. This means that avalanche activity will tend to linger on the north facing slopes.

If all that is not enough to worry about, we have a big warm up coming this weekend, which will certainly make widespread wet avalanches on most aspects and elevations. Like I always preach, just like people, snow does not like rapid changes. We have deep layers of cold, dry snow in the Salt Lake area mountains and the sudden warming will be quite a shock to the snowpack—kind of like the sudden temperature shock we feel when we take a cold shower. The worst days will be Sunday and Monday when we expect ridge top temperatures of 49 and 57 degrees, respectively, with temperatures near 80 degrees in Salt Lake City.

Bottom Line for the Salt Lake, Park City, Provo and Ogden area mountains: The avalanche danger remains MODERATE on mid and upper elevation slopes steeper than about 35 degrees, especially on any slope with recent drifts of wind blown snow. There may be a few wind drifted slopes with a lingering CONSIDERABLE danger along the upper elevations of the Salt Lake area mountains which received the most snow over the last few days. There will be a MODERATE danger of wet avalanching on slopes that become damp with daytime heating. Keep in mind that conditions vary greatly with the slightest change in aspect, elevation and wind drifting.

Mountain Weather:

Today should be similar to yesterday with continued cold, gusty winds from the north and northwest with scattered clouds and occasional, light snow showers. The Weather Graph tells the story. Ridge top temperatures will rise from 14 degrees this morning to 25 degrees by mid day. The weekend through the first part of the week will be clear with rapidly warming temperatures reaching the sweltering category by Monday. Then, it looks like a weak cold front by about Wednesday.

Announcements

The Wasatch Powderbird Guides got out for a couple runs in Cardiff Fork before the strong wind and clouds chased them out. If they can get out today, they will be in Mineral, Cardiff, Days, Silver, Grizzly, White Pine. For more detailed information please call (801) 742-2800 or go to their daily blog.

If you want to get this avalanche advisory e-mailed to you daily click HERE.
UDOT highway avalanche control work info can be found by calling (801) 975-4838.
Our statewide tollfree line is 1-888-999-4019 (early morning, option 8).

Watch video tututorials and fieldwork from UAC staff at our YouTube channel.

The UAC depends on contributions from users like you to support our work.  To find out more about how you can support our efforts to continue providing the avalanche forecasting and education that you expect please visit our Friends page.

If you see any avalanches or interesting snow conditions, please leave us a message at (801) 524-5304 or 1-800-662-4140, or email us at uac@avalanche.org. (Fax 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.

Brett Kobernik will update this advisory by 7:30 on Saturday morning.