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Logan area Avalanche Advisory

7:30, Friday February 29, 2008

Hello and good morning, this is Toby Weed of the Utah Avalanche Center with your Logan Area backcountry avalanche and mountain weather advisory.  Itís Friday February 29th, at 7:30 in the morning.This advisory is brought to you in part by the Friends of the Utah Avalanche Center in Logan with help from Avalanchetools.com.

Current Conditions:A southwest wind will gradually intensify today ahead of a storm that will arrive around midday tomorrow.Expect warm temperatures and mostly sunny skies in the mountains, with high clouds moving in and winds shifting from the southwest and slowly increasing as the day progresses.†† You can still find good, re-crystallized power-like snow on shady slopes, but the sun damaged most others and youíll find sun crusts of varying thicknesses or saturated gloppy snow depending on the time of day.The snow underlying that from the Sunday-Monday storm is mostly supportable and you can ride just about anywhere.Currently under mostly clear skies, the CSI weather station on Logan Peak reports hourly average15 mph northwest winds and a balmy 26 degrees.

Avalanche Conditions:††

I havenít received any reports of slab avalanches locally since Tuesday when snowmobilers triggered a handful of somewhat small slabs along the ridge south of Naomi Peak, (South Cornice Ridge photos).Sunny lower and mid elevation slopes have produced a number of wet, point-release type avalanches in the past couple days, and an observer reports seeing a small skier triggered wet slide north of the mouth of Logan Canyon.

Solar warming will again heat up already moist and crusty snow on sunny slopes at all elevations, and crusts that formed overnight will once again quickly soften.Wet avalanches will be possible on steep slopes in the middle of the day as the surface snow is re-warmed and becomes saturated.†† Watch for roller balling and other wet activity on similar slopes, and leave or reevaluate if the snow on the slope youíre on gets sloppy.

At the beginning of the week, stiff wind slabs formed on south and east facing slopes on a layer of graupel capping a solid sun-crust.These graupel layers have a tendency to enhance facet growth, especially when they fall at the interface between warm old snow and colder new.This and other existing buried weak layers made up of small sugary near surface facets or frosty surface hoar indicate that triggered persistent slabs are possible on some steep slopes.Yesterday evening brought a spike in northwest winds, and after a shift in direction today, southwest winds will be on the increase. So, youíre likely to find a few fresh or forming wind slabs in exposed terrain.Watch for and avoid obvious drifts on steep slopes.Possible clues include; smooth chalky looking snow, hollow sounding stiff snow, shooting cracks, or whumpfing noises

 

†† Bottom Line:Thereís a LOW danger on most shady slopes in the backcountry, and avalanches are generally unlikely in sheltered terrain where the snow stays cold and dry throughout the day.Pockets with a MODERATE danger exist on other slopes, and triggered persistent and wind slab avalanches are possible on some upper elevation slopes steeper than about 40 degrees.†† Solar warming today will cause the danger to increase to MODERATE on steep sunny slopes with saturated surface snow, and both wet sluffs and softened slab avalanches are possible.Use good snow assessment and safe travel techniques to minimize your risks.

Mountain Weather: It will be a warm and sunny day in the mountains today, but winds shifting around and increasing from the southwest will herald the coming of another weekend storm.Expect the winds to significantly increase overnight and clouds will thicken.Saturday will be windy and snow will fly, especially in the afternoon.Iím expecting around 6 inches of accumulation in the mountains.Snow showers will continue into Sunday.The next storm is still on tap for around Tuesday.

General Announcements:

Avalanche class starts this evening: Avalanche Basics, USU Outdoor Recreation Center, Today, Friday February 29th, 6:30p, Field Session tomorrow, Saturday March 1st, 9:00a.  ($35, Please register in advance with the ORC.)  For more information contact [email protected].

Check out the images page for photos of some of this seasonís avalanches.

Go to the Avalanche Encyclopedia if you have any questions about terms I use in the advisory.

I'm very interested to know what you're seeing out there.  Please e-mail observations to me at [email protected] or leave me a message at 755-3638, especially if you see or trigger an avalanche in the backcountry. We keep all observations confidential.

This advisory will expire in 24 hours from the posting time.

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.