Mammoth Area - Sherwins-deep snow conditions & wind slab development

SNOWPACK OBSERVATION The Perch--Trees Mammoth Lakes
Submission Info Forecaster Saturday, February 9, 2019 - 2:45pm

Contributor

Chris Engelhardt

Red Flags:

Recent avalanche activity

Recent loading by new snow, wind, or rain

37° 36' 39.6864" N, 118° 58' 21.8208" W

See map: Google Maps

Snowpit Observations

More detailed information about the snowpack:

HNS: 50cm

Nearly 2ft of new snow fell overnight and through the morning. Conditions in the trees from 9500 ft down on northerly aspects provided the best deepest turns of the season. We did trigger one small wind slab (6"x20'wide, 50'vert) intentionally on a wind loading roll on a NE aspect right below treeline. This was the one sign of instability observed. Upon stomping on windloaded leeward minor ridgelines, was not able to produce cracking or propagation within the snow. Was not able to see anything in the alpine today, nor was willing to venture into it. Skinning was deep, but with the low density of snow, progress was not to ardous. In our area below treeline, snow was welded in place. Northwesterly aspects within the trees were being swept by westerly winds and due north and easterly aspects held deep powder.

Dug a snowpit at 9200ft, NE aspect, 39deg slope.

HS:200cm

HNS: 50cm

CT14 @ 25cm below surface on slight hardness change in new snow. Otherwise completely right side up snowpack with the exception of 4F bottom 35cm of snowpack on ground. Facets at bottom rounding and gaining strength.

ECTX

Snowpack photos:

Snowpit videos (tests, etc):

Weather Observations

Blowing Snow:

Yes

Cloud Cover:

100% of the sky covered by clouds

Air temperature:

Below Freezing

Wind Speed:

Strong

Precipitation:

Snow

Air temperature trend:

Cooling

Wind Direction:

West

Accumulation rate:

Less than 1 in. per hour

More detailed information about the weather:

Steady winds all day, but definitely on the increase around 100pm and by 300pm it was time to depart the mountains. Snow was a blowing and moving every which way with the swirling winds and gusts. Sky was nearly 100% covered in the Mammoth area for most of the afternoon. Nice and chilly keeping the new deep powder good.

16F at 2pm 9200ft