Backcountry Avalanche Forecast for Vail & Summit County
Issued 03/10/2010 7:06 AM by Brad Sawtell

Highlights

Deep slab instability is the number one concern throughout the Vail & Summit County zone. Put a 
lot of thought into your travel habits and your route selection. There is a lot of soft and 
enjoyable snow out there, but think about the consequnces if a large avalanche is triggered.

Pockets of CONSIDERABLE danger still exist. 

Avalanche Danger

There are pockets of CONSIDERABLE danger near and above treeline in the Vail and Summit County 
zone. Recent new snow has been redistributed into sensitive wind slabs on N-NE-E-SE-S aspects 
near and above treeline. Deep slab instabilities lurk on all aspects and elevations. Watch steep, 
cross-loaded terrain features. Below treeline and on westerly facing slopes the danger is MODERATE.

Snow & Avalanche Discussion

A few locations report another inch or two this morning. Snowfall has not come in large quantities 
this week but is has managed to pile up. In the last week, between nine and eighteen inches has 
fallen across the zone. Fortunately winds have behaved. Cornices have grown as well as slabs in 
lee areas. Triggering a freshly formed slab on slopes steeper than 34 degrees is probable.

Prior to the current storm cycle, the snowpack had settled and gained some strength. Natural signs 
of instability are less common but when you see them, they jump out. Large collapses have been felt 
in the Vail Pass area. Many cornices have failed. Deep slab instability is still the number one 
concern. Depending on your aspect, slabs, crusts or dense layers are sandwiching thin layers of 
older near surface facets. Stability is misleading and necessitates sound travel procedures and 
careful route selection. Lately, I have found that because the snowpack is so variable, travel 
habits and route finding skills are even more important.

For now, think about where likely trigger points would be and avoid those areas. Well spaced trees, 
convex roll overs, exposed rocks and near rock bands should be treated as suspect areas. Even though 
the avalanche danger is decreasing a bit, awareness levels should be heightened.

Weather Discussion

Ever stood mesmerized by a taffy pulling machine? Colorado is sitting under weather that sort of 
resembles a puller, sitting between jockeying closed lows. Monday's closed low has climbed back 
into Nebraska, forcing Wednesday's low to drop south and keep heavy precipitation in Northern New 
Mexico. There is weak easterly flow into the Sangres this morning, but little moisture upstream 
over Texas and Oklahoma. Wednesday's low will move into the Texas panhandle today and not be a big 
factor in our weather.

Northwest to northerly flow will develop over Colorado today, squeezed between Monday's low and a 
shallow trough. The low will drag bands of moisture and colder air south into the state. The flow 
is not strong and limit orographics. The Northern and Central Mountains will wring out a few inches 
of snow today, and the San Juans see snow showers. The weak trough will arrive in the afternoon and 
strengthen snowfall, and coupled with convection we could see some locally heavy snowfall. Around 
dark a relatively thin upslope develops east of the Front Range. Little if any snow will spill over 
the Divide.

Light snowfall will continue overnight and into Thursday along the ragged and drying edge of the 
lows. The closed lows will merge and begin to move east. A big, steep high pressure ridge pushes 
into the Great Basin. Skies will be clearing Thursday night and dry northerly flow develops over 
us. The ridge sticks around through the weekend.