Spring Conditions in Valentine Cirque

SNOWPACK OBSERVATION
Valentine Bench and Cirque
Submission Info
Forecaster
Monday, April 9, 2018 - 10:30am
Red Flags: 
Rapid warming
37° 34' 35.4" N, 118° 57' 34.56" W
Snowpit Observations
More detailed information about the snowpack: 

Toured up the Valentine Lake Trail this morning to see how high snowline had climbed on N aspects after the rain storm on 4/6-4/7 and to see how quickly things would warm up today.

I could put my skis on and link patches of snow above 8045', but consistent coverage was not until 8800', and good coverage without having to occasionally walk over bare spots wasn't until 9900'. Rock skis and a sense of caution and adventure were required. Ski crampons also useful.

The snow appeared to have frozen well last night, but the day began warm at 715am. I hiked and skinned in my mid-layer, never needed a jacket all day. At 830am E aspects with sun exposure were begining to warm up to 8900', Tair=8 deg C already. Surfaces still frozen, dry melt-freeze crust.

Runnels of rain and melt water running over and through the snowpack were obvisous on all aspects and elevations up to the very top of the cirque at 11,400'. Spring, melt-freeze snow on all aspects and elevations (where there was snow cover at all).

Several recent large natural point releases in the cirque from the last storm 4/7 (see separate avalanche observation). Many recent rollerballs on all aspects in the cirque. Evidence of an old (probably from the storm cycle 3/21-3/22) D3 slab avalanche that ran from a N aspect and filled the bottom of the cirque with debris and boulders. Crown from this slide was fading but still visible below a cliff band at about 11,100', toe of the debris was the bottom of the bowl at 9700'.

Took some surface observations the middle of the cirque at 10,108' on a N aspect as the snow suddenly transitioned to moist corn at 941am: Surface=moist rounded polycrystals, Ski pen=0cm, Boot pen=1cm, Tair=10 deg C.

By the time I reached the top of the chute looker's L of the Parachute at 1030am the surface had transitioned from frozen melt-freeze crust (Slide-for-life on the way up for sure!, glad I had ski crampons.) to perfect supportable corn skiing. Top 2-4" was creamy wet snow on a supportable crust. Tair at the top of the cirque (11,375') on a SE aspect at 1035am=5deg C. Light E winds at the ridgetop, calm elsewhere. The snow must have changed from frozen to corn in about 45min. I expect that it probably became too wet and unsupportable fast too.

It was a little harder to connect snow patches on the way down the moraine, but I was able to keep my skis on until the exact spot I put them on in the morning. I was off my skis and back walking down the trail at 1130am and I expect that more snow melted this afternoon.

The warm temps combined with the recent rain event transitioning the snowpack to melt-freeze snow "ripe" for melting means that the snow is warming early and fast. Poor refreezing tonight and increasing clouds might cause snowline to sprint even further upslope.

Snowpack photos: 
Skis on at 8045'
Thin but consistent coverage above 8800'
Runnels from the 4/7 rain event on all aspects
Runnels and melt-freeze crusts still frozen at 9am
Runnels to the top of the cirque (11,400') on all asepcts.
Weather Observations
Blowing Snow: 
No
Cloud Cover: 
25% of the sky covered by clouds
Air temperature: 
Above Freezing
Wind Speed: 
Calm
Precipitation: 
None
Air temperature trend: 
Warming
Wind Direction: 
East
Accumulation rate: 
None
More detailed information about the weather: 

ESAC receives support from ...