Eastern Sierra avalanche advisory Posted April 24, 2011 by Sue Burak The avalanche danger is estimated to be mostly LOW with pockets of MODERATE danger for two avalanche problems today. Pockets of dense wind drifted snow could be sensitive to skier triggering in windloaded terrain steeper than 35 degrees on north, east and southeast aspects above 10,000 ft. Wet snow sluffs are possible today on steep sun exposed slopes at mid to high elevations. Yesterday, clouds, wind and light snow and graupel added another layer of wet snow bringing snow totals for the week to 6-10 inches above 10,000 ft. Even though the weather was cloudy and cool yesterday, the snow surface layers were weak enough that it was easy to release large rollerballs on steep slopes below 10,000 ft. It’s almost May and the sun comes up early and sets late, giving the sun’s energy many hours to weaken the snow surface. Another nuisance storm affects our weather today. In many ways this is the same song and dance we've seen over the past few weeks. Brief periods of instability result from passing systems that bring minor snow amounts combined with wind. The trick is that these systems have been nearly continuous; no sooner does the instability from the last storm settle out than the next round arrives. The take-home point is that while spring conditions exist at low to mid elevations, it’s a different story up high. Winter continues to reign on northerly aspects above generally 10,000 to 10,500 ft and skiing and riding conditions are more like February than April – but this means that you should also be thinking about avalanches like you did mid-winter. Wind slabs on steep sheltered slopes will take a little longer to stabilize today. With more sunshine, east and southeast facing slopes that receive sunlight earlier in the day will develop some wet snow problems by mid day and early afternoon. Corn snow will be found on low to mid elevation slopes. Mid elevations in Bishop Creek have been spared some of the sticky wet new snow issues and mid to high elevation south to east slopes are reported to ski well in spring conditions. PRIMARY AVALANCHE CONCERN: WIND DRIFTED SNOW Localized wind drifts and slabs in alpine terrain could be sensitive today because the underlying snow is icy and hard and fast. PRIMARY AVALANCHE CONCERN: WET SLUFFS At mid elevations, wet sluffs will be possible if the sun comes out for any length of time today. Expect to find sluffs on all aspects due to the new snow that will melt quickly and weaken under late April sun. SECONDARY AVALANCHE CONCERN: CORNICE FALL Cornices are huge and several have dropped off this week. Most of the big cornices are still around. Never approach a drop off along a ridge. Today will be quite similar to Saturday’s weather with clouds, a few more hours of sun and fewer periods of graupel and rain. Temperatures at the 8,000 to 9.500 ft elevations will reach seasonal highs in the mid 40’s. Night time lows will be cool with temperatures reaching the low to mid 20’s. No precipitation is expected today and Monday. By this afternoon, ridge top winds will pick up dramatically and by Monday, winds will roar over the area. Mountain communities could experience 75 mph wind gusts. Ridgetops winds over 100 mph will make exposed high elevation terrain icy and hard throughout the day on Monday. A slight warming trend begins Tuesday and Wednesday until another weak storm moves through on Thursday. Daytime temperatures warm up to the 50’s at the mid elevations to around 10,000 ft. Nights warm up to above freezing. Another round of wind and snow is expected for the weekend.