From rain to plowder to powder...but no buried surface hoar

Location Name: 
Forecaster Observation - Peters Ridge, Swan Range
Observation date: 
Thursday, March 15, 2018 - 12:00
Is this an Avalanche Observation: 
No
Observation made by: Forecaster

Tabs

Quick Observation

Traveled into the northern Swan Range to evaluate storm totals, rain/ snow line, and look for buried surface hoar.

  • Rain at the truck turned to snow at approx. 3800'
  • Found 8-20 cm of new snow from overnight and today
    • S1 snowfall observed above 5000' throughout the day
    • Snow density decreased with elevation
  • Good bonding of new snow with the old snow surface
    • Old snow surface consisted primarily of a stout sun crust on sunny aspects and consolidated powder on shady aspects
  • No buried surface hoar observed in snow pits
    • Either from earlier this week or earlier in March (3/3 or 3/7)
  • Light to moderate winds with minimal snow transport
  • No obvious signs of instability such as cracking, collapses, or recent avalanche activity
  • Rollerballs and pinwheels observed below 5000' along steep road cuts on the snowmobile ride out
Snowpack, Avalanche, Weather Images: 
Snowpack, Avalanche, Weather Videos: 

March 15, 2018 - From rain to plowder to powder...but no buried surface hoar

Travel Details
Region: 
Swan Range - West Side (Flathead Valley access)
Route Description: 

Peters Ridge road up to the summer trailhead, then up to the Swan Crest at 6667'.

Activity: 
Skiing
Snowmobiling
Snowpack Details
Snowpack and Weather Details: 
Hide Terrain
Elevation of observation: 
3500-5000 ft
5000-6500 ft
Above 6500 ft
Aspect(s) of observation: 
NE
E
S
SW
W
Red Flags: 
Rollerballs / pinwheels
Persistent Weak Layers: 
Not observed
New Snow in the past 24 hours: 
4.00in.
Total Snow Depth: 
285
More comments about the snowpack and weather: 
West aspect snowpit: Found 10 cm of new, dense snow that fell overnight and today on top of a 4 cm melt freeze crust. 2/8 rain crust (6 cm thick) down 75 cm with 1F hardness snow both above and below. No propagating results in ECTs. North-northeast snowpit: Found 20 cm of new, lighter density snow as compared to west aspect snow pit. ECTN in storm snow above sun crust and no buried surface hoar observed from events this month. Rollerballs and pinwheels noted on steep road cuts below 5000'.
Avalanche Details
Avalanche Details: 
Date and Time of Avalanche: 
Thursday, March 15, 2018 - 18:00