Snowpack Summary for 4/18/2017
Sponsored byUpdated: Tuesday, April 18, 2017 11:23 PM · Issued: Tuesday, April 18, 2017 10:30 PM
Observer: Aaron Hartz
Bottom LineThe central Oregon mountains could receive a few inches of snow over the next few days. The forecast also calls for winds out of the south through west. Wind slabs could once again be on the problem list if we get new snow on the ground. The wind slabs could be shallow, but keep in mind the wind can deposit snow many times deeper on lee slopes. Look for wind slabs forming on northerly through east aspects near and above treeline. This weekend we may see another big increase in air temperature into the mid 40's Fahrenheit. If that happens, we might see shallow wet slabs and/or loose wet avalanches. Watch for wet avalanche problems, especially on sun exposed slopes. Continue to watch for cornices breaking, especially during warm periods. Large cornices can be powerful triggers and can cause deeper layers to fail.
Recent ActivityA relatively large avalanche was reported on a high alpine NE slope on Broken Top over the weekend. The crown was estimated to be over 600ft wide and up to several feet thick and ran 1000ft down to the Bend Glacier. The trigger, type, and when the avalanche occurred are unknown. Aside from that no other reports of avalanche activity have come in.
Snowpack DiscussionIt is difficult to speculate about the layer(s) that were involved with the avalanche on Broken Top reported from the weekend. It is possible the warm up on Saturday weakened the interface between deeper layers in the snowpack. The snowpack does not respond well to rapid changes in temperature. Layer boundaries will remain in the snowpack for a long time. With that said, no reports of specific of weak layers in the snowpack have come in. We have seen several weeks of warm/cold cycles and we have several melt freeze crusts in the upper pack. Our foreseeable avalanche problems will most likely be related to wind loading and surface snow becoming affected by warming.
DISCLAIMER: This snowpack summary describes general backcountry conditions and local variations always occur.