Avalanche danger this weekend?

I'm planning to head out this weekend on a trip through the Teanaways and Enchantments, but the new snowfall at higher elevations is giving me pause. Any thoughts on how this will affect the avalance hazard? I can imagine a foot of new snow sitting on top of a relatively smooth/icy layer that existed before, posing a significant risk of slides. Is that realistic? Should I worry?

Thanks.
-Josh

Is that realistic?  Should I worry?

Yes and yes.

Anytime there is a change in one of the following:

• wind
• precipitation (snow, rain)
• temperature

the avy danger goes up.

I'm planning to head out this weekend on a trip through the Teanaways and Enchantments . . . I can imagine a foot of new snow sitting on top of a relatively smooth/icy layer that existed before . . .  Is that realistic?

Well, that particular scenario is not very realistic this week, because there has been very little precip in the Teanaways and Enchantments, far less than 1" -- so the likelihood of 1 foot of new snow anywhere in that area is near-zero.

How can one know that? Unfortunately, the Teanaways and Enchantments are a black hole for data: there are no snow telemetry sites anywhere nearby (meaning in the same snow-climate), nor are there any other weather telemetry sites which give precip. Very lame.

The nearest SNOTEL sites to Mount Stuart (the center of that region) are Fish Lake and Sasse Ridge, both about 10 miles farther west and much closer to the Cascade Crest (see this map: www.or.nrcs.usda.gov/snow/maps/yakima_basin_map.html ). These two sites are in a wetter, snowier climate than the Teanaways and Enchantments, each with an average annual precip of about 62" (even though they are very dry compared to the Crest itself near Snoqualmie Pass which averages over 130" annually), and they have each gotten just under 1" of precip since May 20.

A similar distance east of the central Teanaways is Blewett Pass, which has an average annual precip of only 36" and has gotten about 0.3" since May 20. Farther east, the Mission Ridge NWAC site has also gotten about 0.3" of precip.

So the total precip since May 20 in the Teanaways and Enchantments is most likely somewhere between 0.3" and 1", probably about halfway in between. And 0.6-0.7" of precip is only going to produce about 4-6" of snow given recent freezing levels and temperatures. Even assuming that the greater elevation of the high peaks of the Teanaways and Enchantments has enhanced the precip amounts, it would still be unlikely to be over 1", so a foot of new snow is not likely.

Whether you will face avalanche hazard on the peak or route you intend to ski this weekend is an entirely different question, though. But it won't be from a foot of new snow in that region at this time.

Amar,

While I imagine its pretty likely you're correct with your estimates on how much snow has fallen recently east of the crest, I thought for the sake of discussion I would mention that you did not talk about the possible effect of wind-transport.

Granted, I have not checked any telemetry stations to see what the winds have been like during our recent batch of bad weather, but a few weeks back some friends of mine and I headed in to Mt.Stuart after several days of poor weather. We encountered generally light amounts of new snow at Longs Pass, and large areas that were completely devoid of new snow on the climb up, but we did have high winds the day before and that managed to create isolated pockets of snow that were easily more than a foot deep...some areas that were knee deep...and when the sun cooked the upper slopes, we had a significant avy hazard.

Anyways...just something to posisbly consider.

Yeah, thought about wind transport while trying to figure out how much precip that region actually got. But wasn't sure what to say about it in the post since there's no way to quantify it. Even worse, the only wind data near that region is from Mission Ridge, but that has been totally screwed up and giving negative values for some time. The top of Alpental did have fairly high winds over the last 2 days since Monday evening, but that's far away and not well correlated with locations well east of the Crest due to the effects of pass flow.

But when most people ask about a foot of new snow and the hazard it creates, they are thinking of a real foot of new snow (on the wind-protected flats), not more like 4-6" which has wind drifted. A real foot of new snow has the potential to create far more significant new-snow avalanche hazards, including 2-3 ft thick dense windslabs, etc.

Of course, my precip estimates could also be too low (or even too high), since there really is no useful snow/precip data from the region.

Thanks for the informative discussion. Since I'll be traveling alone, I've decided to relocate my trip to someplace with lower-angle slopes and more trees in order to minimize the risks.

-Josh