Loose Wet
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 1
A decent snow surface refreeze is expected to have occurred last night, mostly the result of radiational cooling under clear skies. Air temperatures at 5:30 am this morning were in the mid to upper 30s for most locations. A few upper elevation stations in the 8,000' to 9,700' range were reporting air temperatures in the 29 to 31 degree range. Winds out of the SW last night kept air temperature inversion conditions to a minimum.
Rapid warming is expected this morning. There is some uncertainty as to how much cloud cover will exist over the forecast area this afternoon. If skies remain sunny into the afternoon hours, areas of loose wet snow instability will form. If significant cloud cover develops and is able to slow the rate of snow surface melt before last night's melt-freeze crust loses supportability, then fewer areas of loose wet instability will form today.
Monitor the strength of the melt-freeze crust, just below any surface wet snow by paying attention to the depth of penetration of boots and equipment into the upper snowpack. Once last night's refreeze melts away and boots and equipment easily penetrate into the deep wet snow below, it is time to vacate avalanche terrain. The vast majority of wet snow instability is expected on E-SE-S-SW-W aspects at all elevations and on NW-N-NE aspects below 8,000' to 8,500'. In these areas, loose wet avalanches are possible today. Timing travel in avalanche terrain is critical. When dealing with wet snow instability, the difference between a stable and unstable slope can be as little as 15 minutes worth of additional melt. Late starts for travel in avalanche terrain on warm sunny spring days are not advised.