Eastern Sierra Avalanche Forecast - 1/3/15

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THIS AVALANCHE ADVISORY EXPIRED ON January 4, 2015 @ 7:00 am
Avalanche Advisory published on January 3, 2015 @ 7:00 am
Issued by Sue Burak - Inyo National Forest
advisory discussion

Blue skies, rebounding daytime temperatures and light winds signal the end of a very cold and windy week. Morning low temperatures have rebounded more than 25 degrees and yesterday was pleasant above treeline as long as the north wind didn't blow. The weather pattern so far this season is one extreme to another- after days of high temperatures in the teens and low 20's and wind chills well below zero, daytime highs will challenge 50 degrees by Monday.  This see-saw of 30 degree swings in temperatures in weekly cycles inhibits the formation of depth hoar, while facets remain small. The sun angle is still very low so the influence of warmer days will be offset by short days and cold nights. Expect to see snow surfaces become glazed and wet at mid elevations next week. In places where the snowpack is thin, expect some daytime melt to occur.  In the presence of a lessening temperature gradient, facets could begin to round and bond- at least until the next cold inside slider arrives in a week.

recent observations

Hundreds of acres of wind damaged snow was found on south,west, north and east aspects along the San Joaquin Ridge yesterday. There was no evidence of wind deposited snow on any aspect. Sastrugi was 60 to 90 cm in height in isolated areas where the wind was particularly vicious. East and northeast facing slopes were littered with mini slabs that failed when the wind undercut sastrugi to the point where the snow fell off.  Slide for life conditions were found on moderately steep slopes facing east and northeast. There was no evidence of soft snow in the bottom of Deadman Bowl. Extended column tests did not produce fracture or propagation. Multiple compression tests failed in the hard range at 15, 25 and 30 cm with low energy. 

In sheltered, shaded north facing terrain we found areas of settled snow and areas with surface layers of wind affected snow. Extended column tests in this location at 9,500 ft. did not fracture or propagate (ECTNR).

 

 

 

 

 

 

 

 

 

CURRENT CONDITIONS Weather Observations Between June (10,000 ft.) and Mammoth (11,000 ft.)
0600 temperature: 21 deg. F.
Max. temperature in the last 24 hours: 37 deg. F.
Average wind direction during the last 24 hours: NE
Average wind speed during the last 24 hours: 25 mph
Maximum wind gust in the last 24 hours: 41 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 23 inches
weather

Arctic air remains in the wake of the recent storm system and the strong cold front of this past Tuesday. The airmass has finally begun to modify as an upper-level ridge continues to build overtop. This evolving pattern will dominate our weather for the next several days (into the middle of next week) yielding nice bluebird skies and daytime temperatures rebounding gradually over the period. Evenings will be very cold with intense morning inversions in the Crowley Lk and June Lake areas. Higher elevations should be pleasant from mid-late morning through the day and will be an escape from the morning inversions in low lying areas. Air temperatures this morning are in the 20's above 9,000 ft in the Mammoth Basin while low lying areas such as Devils Postpile and June Lake are in the low teens or single digits.

Northeast winds will continue to blow over the high ridges but instead of the sustained 80-100 mph northeast winds earlier in the week, sedate breezes 10 to 15 mph, gusting to 25 mph will continue today. By Sunday as the ridge builds and amplifies, winds will be from the west. Temperatures at the 10,000 to 11,000 ft elevations will reach the mid 40's on Sunday and hit 50F by Tuesday.

The only hope for precipitation occurs when the ridge builds to such high amplitude that it pinches off and a storm can sneak in under the ridge.

 

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8,000 ft. to 10,000 ft.
  Saturday Saturday Night Sunday
Weather: Sunny clear sunny
Temperatures: 47 deg. F. 22 deg. F. 41 deg. F.
Wind direction: NE NE W
Wind speed: 5-10 5 5
Expected snowfall: 0 in. 0 in. 0 in.
Over 10,000 ft.
  Saturday Saturday Night Sunday
Weather: sun sun sun
Temperatures: 38 deg. F. 26 deg. F. 36 deg. F.
Wind direction: NE NE W
Wind speed: 10-15 5-10 10-15
Expected snowfall: 0 in. 0 in. 0 in.
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