Marginal re-freeze on Tallac

Location Name: 
Tallac
Region: 
Desolation Wilderness Area (including Emerald Bay)
Date and time of observation: 
Mon, 04/23/2012 - 09:30
Location Map: 
United States
38° 53' 59.7012" N, 120° 5' 16.9224" W
US


Red Flags: 
Recent avalanche activity
Rapid warming

Observation made by: Professional Observer
Snowpit Observations
More detailed information about the snowpack: 

Very warm morning on Tallac, with minimal overnight re-freeze: rushing creeks, water and mud puddles on summer trail at 7000ft , and even swarms of mosquitos by 8am. Maximum thickness of incipient MFcr observed to be 5cm, and was fully melted by 9am. Ski pen on NE aspects at 8000ft was already 10cm deep by 9am, had increased to 20cm by 10am, and did not show signs of improving with elevation gain. Signs of recent (~24hrs) wet loose activity, both natural and human triggered, on NE, E, SE aspects including one small human triggered on surprisingly low angled terrain (30 degrees, E aspect, 8500ft). Top 20cm of snow was easy to get moving on low angled slopes by 10am.

At 9:30am at provided lat/long on NE aspect, melt forms were observed all the way to the ground with an HS of 215cm. Snowpack consisted entirely of rounded polycrystals and old crusts. Very wet snow (water visible to naked eye) down to 130cm from ground. Rounded polycrystals below 130cm were in refrozen state. January PWL (61-63cm from ground) at this location consisted of rounded polycrystals only slightly softer in hand harness than the crust above and below, and was not reactive to 2x Deep Tap tests.

Pic: Convective clouds already building in height and getting darker by 9am. Appeared to be some virga (rain falling but evaporating before hitting ground), but no rain hitting ground by my departure at 11am.

Snowpack photos: 
Weather Observations
Blowing Snow: 
No
Air temperature: 
Above Freezing
Wind Speed: 
Calm
Precipitation: 
None
Air temperature trend: 
Warming
Wind Direction: 
Accumulation rate: 
None
More detailed information about the weather: