THIS SNOWPACK SUMMARY EXPIRED ON March 25, 2021 @ 9:56 am
Snowpack Summary published on March 24, 2021 @ 9:56 am
Issued by Arden Feldman - Bridgeport Avalanche Center

bottom line:

Watch out for isolated areas of wind drifted snow and soft slabs near and above tree line today. These wind slabs may be in unusual locations from the recent northeast winds. Terrain selection is essential when dealing with small avalanches.

Avalanche Character 1: Wind Slab
Wind Slab avalanches release naturally during wind events and can be triggered for up to a week after a wind event. They form in lee and cross-loaded terrain features. Avoid them by sticking to wind sheltered or wind scoured areas.

Unusual strong NE winds combined with recent snowfall has created isolated small wind slabs near and above tree line. Look out for signs of instability like cracking and collapsing and avoid smooth and rounded looking drifts in steep terrain.

Snowpack Discussion

It’s been cold- over the last three days, air temperatures around Leavitt Lake have ranged from 25 to 30 degrees F. Daytime highs could reach 34F today, then fall almost 10 degrees on Thursday as the storm moves through the area.  The last few weeks have seen a series of cutoff lows- weak storms that track to the east of the Sierra that drop a few inches of dry and light snow. 

Observations from the McKay Creek area yesterday revealed a potpourri of snow surfaces- fresh snow sitting on top of melt freeze crusts, deeper deposits of wind drifted snow near treeline. North to NE winds had recently formed areas of wind drifted snow and small wind slabs on southeast to northwest aspects, especially near ridgetops. unusual aspects for an area that typically receives southwest winds during storms. Reports from the Virginia Lakes area show isolated areas of cold snow in steep sheltered north facing terrain. 

North to east winds will continue to blow today, so be on the lookout for areas of wind drifted snow and small wind slabs on south to west aspects, especially under ridgetops. Areas of wind drifted snow could also be found in the usual locations- steep north facing slopes under ridgetops. These drifts could produce short, non-propagating cracks under skis as shown in the observation from yesterday. Tonight into tomorrow, winds will shift to blow out of the west, so look out for redistributed wind slabs on easterly aspects. On steep northerly slopes protected from the winds, sluffing (dry loose avalanches) within the new snow will also be possible. 

With partly cloudy skies forecasted for today, the sun may be able to heat up snow surfaces on southerly aspects enough to produce small loose wet avalanches in the fresh snow. Watch out for signs of instability like rollerballs. Change your slope aspect to find drier snow or decrease your slope angle to avoid this problem if you find it. 

CURRENT CONDITIONS Weather observations from Sonora Pass
0600 temperature: 15 deg. F.
Max. temperature in the last 24 hours: 17 deg. F.
Average wind direction during the last 24 hours: Northeast
Average wind speed during the last 24 hours: 10-20 mph
Maximum wind gust in the last 24 hours: 34 mph
New snowfall in the last 24 hours: 1 inches
Total snow depth: 106 inches
weather

This morning under mostly clear skies, mountain temperatures are in the low teens across the forecast area. Breezy north to east winds are blowing 15-20 mph at higher elevations.  Expect mostly sunny skies today with a few degrees of warming- highs may reach 40F in the Leavitt Lk areas. Another cold storm is expected to drop a few inches of snow tomorrow and tomorrow night. 

A brief warming trend today will be short lived as another cold moisture starved storm moves through the area tonight. Expect continued cold temperatures, and another few inches of snow above 8,500 ft.

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8000 ft. to 10000 ft.
  Wednesday Wednesday Night Thursday
Weather: Sunny then becoming partly cloudy. Mostly cloudy. Partly cloudy. Chance of snow showers in the afternoon.
Temperatures: 35 to 43 deg. F. 17 to 23 deg. F. 27 to 35 deg. F.
Wind direction: Northwest West West
Wind speed: Around 15 mph. Gusts up to 40 mph in the morning. Around 15 mph with gusts to 30 mph. Around 15 mph with gusts to 35 mph.
Expected snowfall: 0 in. 0 in. 60% probability no accumulation. 40% probability up to 1 in.
For above 10000 ft.
  Wednesday Wednesday Night Thursday
Weather: Sunny then becoming partly cloudy. Mostly cloudy. Mostly cloudy. Chance of snow showers in the afternoon.
Temperatures: 27 to 33 deg. F. 10 to 16 deg. F. 18 to 26 deg. F.
Wind direction: Northwest Southwest Southwest
Wind speed: 15 to 30 mph. Gusts up to 50 mph decreasing to 25 mph in the afternoon. 15 to 25 mph. Gusts up to 30 mph increasing to 40 mph after midnight. 15 to 30 mph with gusts to 45 mph shifting to the west 15 to 20 mph with gusts to 30 mph in the afternoon.
Expected snowfall: 0 in. 0 in. 60% probability no accumulation. 40% probability up to 1 in.
Disclaimer

This snowpack summary applies only to backcountry areas in the Bridgeport Winter Recreation Area. Click here for a map of the area. This snowpack summary describes general avalanche conditions and local variations always occur. This snowpack summary expires in 48 hours unless otherwise noted. The information in this snowpack summary is provided by the USDA Forest Service who is solely responsible for its content.