Eastern Sierra Avalanche Forecast - 1/22/14

Avalanche Advisory published on January 22, 2014 @ 7:37 am
Issued by Sue Burak - Inyo National Forest

We are waiting for snow before advisories can be posted. See the update below.

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advisory discussion

In order to have an avalanche, you need a weak layer and a slab. The snowpack in all the places we have traveled in the past month, is the same- well developed facets and depth hoar sandwicjhed between three or four sun crusts.  In some places, on east and north facing slopes, facets and depth hoar have become more dense by internal repacking of the individual crystals. This results in a slab overlying weak facets.

While this sounds like an avalanche problem, the sad truth is that this combination exists in many places but the snow is only 6-15 inches deep in most places- it’s a miniaturized snowpack profile. If there was 4 feet of snow,  the avalanche problem would be buried persistent weak layers and weak snow on the ground.

But 15 inches of  snow is not enough for a continuous snow cover. Slopes with snow are punctuated with rocks, downed trees, streams and bare ground.  How much snow will it take to revive the snowpack,  bring smiles to everyone and add some excitement to my job? 

In order to answer this question, I looked at  snowfall records on Mammoth Mountain and Mammoth Pass. There was  more snow on the ground in January  1987-192, a well known period of drought.   The winter of 1990-1991  was the driest winter so far and compares favorably to this year.  At the end of January 1991, only 46 inches of snow had fallen at the Sesame Street study plot. This year, 48 inches have been measured.  Of course in 1991, the storm door opened at the end of February and 25” of water accumulated during the month of March- the so called “Miracle March”.   May the “Ridiculously Resilient Ridge’” break down  soon.

I estimate we need a couple of inches of water and 24 inches of snow to allow skiing and avalanche problems to return to the Mammoth Lakes Basin.  A foot of new snow will cover some of the rocks but a foot of new snow over 6 inches will freshen the view but put us back to early December when there was limited skiing only in places with small pumice on the ground, like the Red Cone Bowl.

If it’s any comfort at all, the Mt Shasta avalanche center does not have enough snow to issue avalanche advisories- Mt Shasta is an icy, crevasse filled mountain now.  The Lake Tahoe area has a little more snow and my colleague at the Sierra Avalanche Center has at least 6 places where he can link turns.

We are now approaching the half-way point of the winter snow accumulations season in the western mountains and the snowpack situation is looking pretty dire in most areas except those near the Continental Divide of Colorado, Wyoming, and Montana.


weather summary

Expect cloudy and cooler conditions this week.  Temperatures will fall 5 to 10 degrees by Thursday but are still above normal for this time of year. East winds will develop by Thursday.

Morning lows above 10,000 ft will remain in the upper 20’s to 32F. Lower elevations are colder with lows in the teens. Daytime highs remain in the upper 40’s, falling only to the low to mid 40’s by Thursday.

Weather Observations Between June (10,000 ft.) and Mammoth (11,000 ft.)
0600 temperature: 33 deg. F.
Max. temperature in the last 24 hours: 48 deg. F.
Average wind direction during the last 24 hours: N
Average wind speed during the last 24 hours: 5-10 mph
Maximum wind gust in the last 24 hours: 12 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 0 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8,000 ft. to 10,000 ft.
Wednesday Wednesday Night Thursday
Weather: partly cloudy, then sun clear partly cloudy
Temperatures: 46-52 deg. F. 23-29 deg. F. 32-39 deg. F.
Mid Slope Winds: N N E
Expected snowfall: 0 in. 0 in. 0 in.
Over 10,000 ft.
Wednesday Wednesday Night Thursday
Weather: partly cloudy partly cloudy partly cloudy
Temperatures: 41-47 deg. F. 18-28 deg. F. 31-37 deg. F.
Ridge Top Winds: N N E
Expected snowfall: 0 in. 0 in. 0 in.
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