|Avalanche Advisory published on May 2, 2014 @ 7:01am:||Issued by Sue Burak - Inyo National Forest This advisory is valid for 24 hours.|
avalanche dangerHow to read the advisory
|Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.||Natural and human-triggered avalanches unlikely.||Small avalanches in isolated areas or extreme terrain.|
A ridge of high pressure will bring warm temperatures and low humidities to our area through Saturday. Temperatures will be in the 60's in the Mammoth area and mid to high 50's above 10,000 ft. Snowmelt will cause minor rises in local streams.
A low pressure area will move into the Pacific Northwest this weekend bringing increasingly windy conditions to our area starting Saturday, lasting into Monday. Southwest winds gusting 35-45 mph are likely each day, especially in the afternoons and evenings. Ridges in the Sierra could see gusts 60-80 mph. This storm is likely to bring scattered showers to the region Monday into Tuesday but precipitation amounts are not expected to be significant.
After last weekend's storm, cool temperatures and northeast winds kept the snow surface from heating up. You can still find settled powder in steep sheltered north facing couloirs. The northeast winds did create some wind affected snow along upper elevation ridges. A gradual warming trend through the week and cold temperatures at night kept wet snow avalanche activity limited to a few east and north facing slopes. The gradual warm up this week helped stabilize the snow because after a few days of melt water getting into the storm snow, the snow becomes homogenous and a spring melt freeze cycle sets up. Spring snow conditions are the best of the season.
Spring is synonymous with wet avalanches. With the sun higher in the sky and daytime air temperatures above freezing, wet avalanche activity increases. More importantly, above freezing temperatures at night add to the danger and can create unstable conditions. Wet snow avalanches can occur anytime during the spring and early summer.
This time of year the sun is close to its maximum strength. If night time low temperatures are above freezing, the snow warms up rapidly. If skies are cloudy overnight, you can expect wet snow avalanche conditions by mid morning. If the snow gets a good refreeze, avalanche conditions can occur later in the day or not at all. You can use the Mammoth Mountain Ski Patrol site, http://patrol.mammothmountain.com/OtherWxStations.html or http://www.wrh.noaa.gov/mesowest/mwmap.php?map=hnx to monitor air temperatures throughout the forecast area.
Pinwheels and large rollers of snow are signs of increasing avalanche danger. Punching to the ground in wet, unsupportable snow is another bad sign. Wet avalanches, whether loose snow or slab, can be destructive and powerful. Moving to a different aspect with less sun exposure, and less than 25 degrees in slope angle without steeper terrain above it, or simply heading over to the local crag all represent great alternatives to getting cart wheeled around in a wet slide.
The long range forecast is for unsettled weather in May. Spring snow storms can occur. Expect a period of snowpack instability during the storm itself, then a second cycle of avalanche activity when the sun comes out and the snow has to deal with rapdi change. New snow will be very sensitive to rapid warming and direct sunlight. Pay close attention to new snow and to the old snow surface beneath it. It can lose strength rapidly as the day progresses causing a significant increase in avalanche danger.
Cornices formed this season during the March and April storms. Even though cornices are small compared to the monster cornices that can form, a cornice fall can entrain loose surface snow or trigger deep slab avalanches. Regardless of whether a cornice triggers a larger slide or not, a falling cornice is dangerous to anyone in its path.
Thanks to everyone who donated money to support the work of the avalanche center. I would like to thank Preston Few and Ryan Floyd who provided me with snow and avalanche observations and accompanied me in the field.
ESAC Weather Page
Weather Station Links:
June Mountain Summit
|CURRENT CONDITIONS Weather Observations Between June (10,000 ft.) and Mammoth (11,000 ft.)|
|0600 temperature:||35 deg. F.|
|Max. temperature in the last 24 hours:||63 deg. F.|
|Average wind direction during the last 24 hours:||SW|
|Average wind speed during the last 24 hours:||15-20 mph|
|Maximum wind gust in the last 24 hours:||30 mph|
|New snowfall in the last 24 hours:||0 inches|
|Total snow depth:||16 inches|
|Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS|
This advisory applies only to backcountry areas outside established ski area boundaries. This advisory only describes general avalanche conditions and local variations always occur. This advisory expires 24 hours after the posted time unless otherwise noted. The information in this advisory is provided by the USDA Forest Service who is solely responsible for its content.