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, February 29, 2008 7:30 am
Good morning, this is Drew Hardesty with the Forest Service Utah Avalanche Center with your backcountry avalanche and mountain weather advisory. Today is Friday, February 29, 2008 and it’s about 7:30 am.

Current Conditions:

Skies remain clear under the soon-to-be-out-the-door ridge of high pressure. Temperatures are in the mid-20’s up high, with the cold air sinks registering overnight lows in the mid to upper teens. This morning, winds aloft are light from the northwest, although they bumped into the 20-25mph range with gusts to 35 during the overnight hours. Riding conditions remain excellent in the mid and upper elevation shady slopes, with what amounts to semi-corn conditions on the steeper sunny aspects. On another note, there have been at least 3 negative interactions with moose on some of the popular trails in Big Cottonwood Canyon. All the snow we’ve received at the mid and low elevations has stressed these guys out, so for their well being, as well as yours, give them a wide berth.

Snow and Avalanche Discussion:

The only news we heard about, beyond a few wet sluffs, was a natural cornice fall along the Park City ridgeline and a couple explosive-induced pockety wind slabs in high terrain.

As winter shifts to spring, so our focus shifts to include the southern end of the compass. Faceted snow there above a melt freeze crust sits buried 1-2’ beneath the snow, and was responsible for a number of wet slab naturals and close calls with human triggered slides on Tuesday and Wednesday. Rapid warming also contributed to the number of incidents on the steep sunny exits back on Saturday, with the loose wet snow instigating a number of ‘unintentional hip checks’ to the way-late skiers. It’s time to calibrate our timed exits and windows on the steepest sun-exposed slopes. By the time you’re sinking in and/or seeing roller balls, say by about late morning, you’re too late.

Other weak layers on and just beneath the snow surface abound and it will again be important to map these prior to Saturday’s quick hitting cold front. Surface hoar and graupel are two of the potential players, and are both driven by localized weather events. The graupel, driven by localized updrafts and convective instabilities can easily be found in one drainage and not another. Surface hoar, often sensitive to cloud cover, wind, and temperatures, too, can be developed or destroyed in neighboring sub-drainages. And until they come up with a weak snow detector, we’re stuck with mapping snow surfaces and poking in the snow once they’re buried. As our good friend Lynne Wolfe (she’s the editor of the Avalanche Review) from the Tetons likes to say, today’s snow surface is tomorrow’s weak layer.

Bottom Line for the Ogden, Salt Lake, Park City and Provo area mountains:

Isolated pockets of MODERATE exist in the shady mid and upper elevation terrain for triggering newer wind drifts and graupel slabs. On the other end of the compass the danger will rapidly rise to MODERATE on all the sun exposed slopes with daytime heating. Sagging cornices will again be concern – give them a wide berth there on the windward side of the ridgelines.

Mountain Weather:

We’ll have clear skies, and with the ridge shifting slowly to the east, the winds will back to the southwest but remain at or less than 15mph. 8000 and 10,000’ temps will again be in the low forties and thirties, respectively. A vigorous, but fleeting cold front moves through tomorrow afternoon that should be good for 6-10” in northwest-flow favored terrain, with a few minor disturbances on tap for early next week.

Announcements
The Wasatch Powderbird Guides flew yesterday in Mineral, Cardiff, Days, Grizzly and Cascade. Today they will be in Mineral, Cardiff, Days, Silver, Grizzly, White Pine, Cascade and American Fork. 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 [email protected]. (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.

Evelyn Lees will update this advisory by 7:30 on Saturday morning.