US Forest Service Manti-La Sal National Forest

Snow, Weather and Avalanche Advisory

 Introduction:

This is Max Forgensi with the USFS Manti-La Sal Avalanche Center with your with your avalanche and mountain weather advisory for the Wasatch Plateau/Manti Skyline Region, including, but not limited to Ephraim, Huntington and Fairview Canyons. This advisory is brought to you through a partnership of Utah State Parks and the USFS. Today is Saturday, February19th, 2005 at 7:30 am.

Current Conditions:

A SNOW ADVISORY IS IN EFFECT UNTIL 5 PM MST SATURDAY for the Manti-Skyline. Very strong winds and periods of heavy snowfall will cause considerable blowing and drifting of snow, increasing the avalanche hazard and compromising road conditions. Yesterday, the snow started to fly and snowed on and off throughout the afternoon. Buried sun crusts and cornice development is what’s on tap for today…there is plenty of snow on everyone’s favorite designated trails and powder fields, once again this weekend will be a good time to stay away from the steeper terrain until the snow stops falling and wind stops a blowing. There will be increased traffic on the Skyline for President’s Weekend, please drive defensively and park courteously.

Mammoth/Cottonwood SNOTEL: 50” of snow on the ground.

Miller Flat Trailhead: 54” of snow on the ground, 1” new fell as of 2:00 pm yesterday.

Mountain Weather:

A large unstable mass of moisture will effect the area through Presidents Weekend and into the better half of the work week.

Saturday: Snow. Accumulations of 6-8” of snow expected. High near 30.

Saturday night: Breezy. Snowy. Accumulations of 2-4” expected. Low at 8,000’ near 20 degrees. Winds will be out of the Southwest at 15-25 mph.

Sunday: Breezy. Snow. Accumulations possible. High temperatures will be in the lower 30’s. Winds will be out of the West at 15-25 mph.

Avalanche Conditions:

There are two concepts one must think about before heading out on the Skyline today, the current hazard and the potential hazard. The storm that rolled through last weekend left a very dense (moist) layer of snow overlying a less dense layer of snow. The strength of the current snow pack was strong enough to stay on the slopes and produce few if any natural avalanches in the past week. It was under a precarious balance that if given the proper trigger, a snowmobile for example, might fail. We had two snowmobile triggered avalanches on the Skyline this past week on North-East slopes. Why isn’t there many natural avalanches? Well, the snow on the ground is waiting for an adequate stress to be applied to it. The currente storm will tip the scales and we will have a natural avalanche cycle. But where? The will be strong winds coming in from the Southwest and west, distributing new snow onto the leeward slopes on North through East aspects. Expect cornices to be tender and crack farther back than expected and wind-loading on these slopes that could fail.

The Bottom Line is an avalanche danger of CONSIDERABLE on steep slopes on North through East aspects and around recently deposited cornices. Depending on how fast the snow falls and wind blows, there could be a period of time late tomorrow afternoon where the avalanche danger could be a HIGH avalanche danger. Remember, a HIGH avalanche danger means that natural avalanches are likely and human-triggered avalanches are likely as well. Keep your slope angles today below 30 degrees, and work on those snowmobile tricks out in the meadows!