Good morning, this is Sue Burak with the Eastern Sierra Avalanche Center with an avalanche advisory posted for Tuesday April 15, 2008. MOUNTAIN WEATHER One thing is for sure- the old saying, If you dont like the weather, wait a few minutes and it will change has been operational the last couple of weeks. The only thing for sure is that we are not getting any new snow this spring from these dry storms that produce CONSIDERABLE avalanche danger ratings in the Canadian Rockies. After yesterdays 90-100 mph wind event, this mornings winds are back to more typical wind speeds. The top of Mammoth is 40-50 mph from the southwest and Tioga Pass, Ellery Lake and Lake Sabrina are gusting to about 20 mph. The highest wind speeds were recorded on Chair 1 and Lee Vining Hill with wind gusts of 116 and 130 mph respectively. Morning temperatures have cooled dramatically, down 15-20 F degrees from yesterday mornings 6 AM lows. Todays highs will be much colder with highs reaching the low 30s at the 9,000 to 10,000 ft elevations. Higher elevations will be cool with highs in the low to mid 20s. Wind advisories expired this morning for Inyo County at 7 AM, though the forecast is for continued windy conditions today in the mountains in Mono and Inyo County as the cold front moves south. North to northwest flow will replace this mornings southerly flow and slow tomorrows warmup. As the ridge builds back in on Wednesday, temperatures will increase about 10 F Wednesday and Thursday. By Friday, another strong, windy dry storm affects the Sierra. Wind advisories are expected for the weekend event with much cooler temperatures expected. SNOWPACK AND AVALANCHE DISCUSSION Good thing the weather turned cold. At the rate was snowpack was melting, spring skiing would have ended a couple of weeks early. With freezing levels above 10,000 ft over the weekend in some places, snowmelt really took off. Over the last 6 days, about 12 inches of snow has consolidated and melted. Despite dire warnings of increased wet snow avalanches, very few natural wet slides were observed or reported over the weekend. Yesterdays winds and low relative humidities provided significant amounts of energy to melt snow. Over 2 inches melted during the course of the day in many wind exposed locations. With below freezing temperatures last night and today, the melt process will have to restart rather than being maintained, by incoming solar energy. This is not expected to occur until tomorrow or Thursday. Strong winds also assist the development of sun cups and other surface features. Once some unevenness of the snow surface develops, winds flowing across the snow surface hasten the growth of suncups. Suncup peaks favor evaporation , while calmer air in the valleys favors condensation onto the snow surface and conduction related melt. Once the snow surface is wet, the melting process really takes off and the difference in height increases between the peaks and valleys of suncups. For today and Wednesday, there will be no suncup formation, though the process will start up again over the weekend. BOTTOM LINE With cold temperatures and windy conditions today limiting snow surface melt, the avalanche danger rating is LOW above 9,000 ft. Please note that the avalanche danger rating in this advisory expires in 24 hours. This advisory is our best interpretation of snow pack conditions and NWS forecasts issued today. Backcountry travelers should be aware that elevation and geographic distinctions are approximate and that a transition zone exists between upper and lower elevations. Avalanches do not happen by accident and most human involvement is a matter of choice not chance. Most avalanche accidents are caused by slab avalanches that are triggered by the victim of member of the victim's party. Even small slides can be dangerous. Always practice route finding skills and carry avalanche rescue gear. Remember that avalanche danger ratings are only general guidelines. Distinctions between geographic areas, elevations, slope aspects and slope angles should be made.