*This will be the final Snowpack Summary of the 2018/2019 season. Please continue to submit your Observations and use the Observations Page as a resource throughout the remainder of the spring season.
A typical spring snowpack exists throughout the forecast area, and the avalanche hazard is becoming more predictable. While instabilities related to warming will remain the greatest concern for the remainder of the spring, precipitation events will also have a significant effect on stability. Keep an eye on the weather in your local area and be ready for changing conditions. Each new storm will bring a period of elevated avalanche concern. Areas that see substantial snowfall may see a period of increased storm and wind slab hazard during and immediately following a storm. Expect a second cycle of instability following a storm event as rapid warming and solar radiation affect the new snow. Freshly formed wind slabs may become more sensitive during periods of rapid warming, and loose wet avalanches will become more likely as the new snow settles.
As we look forward to this coming week, unsettled weather is very likely. Low pressure will move across the range over the next few days (May 9-11) bringing increased winds, thunderstorms, and snow showers above 8500’. Precipitation totals will vary across the forecast area. Models suggest larger amounts for the southern part of the range, with snow totals approaching double digits at higher elevations. While this weekend holds the greatest chance for significant precipitation, cloudy skies and scattered showers will likely continue into next week. (May 12-15) It will be important to keep track of the weather throughout the remainder of the spring and evaluate how it’s affecting the local snow conditions.
As the unsettled weather clears and a more typical melt-freeze cycle returns, remember that timing is important. Climb slopes while they are firm and be off suspect slopes before they become too loose and unconsolidated. The sun will cause easterly aspects to transition first in the morning, followed by southerly and westerly aspects later in the afternoon. Pay attention to overnight temperatures, as a weak refreeze will lead to a faster transition in the morning. It's also worth remembering that thin cloud cover can cause strong green housing effects, trapping solar radiation and encouraging more extensive warming. Increasing boot penetration is a good sign of surface instability, don’t be afraid to turn around if the snow below your feet becomes loose and unsupportive.
Beyond the typical spring avalanche concerns, keep in mind how changing surface conditions will affect your travels. Hard, slick surfaces can make travel challenging and dangerous without the proper equipment such as an ice ax, and ski or boot crampons. Uneven surface conditions resulting from sun cups or old tracks can make for challenging skiing conditions. Furthermore, the diminishing low elevation snowpack will impact route choice. Do your homework before you embark on a big mission. Check on road access, approach conditions, evaluate stream crossings with care, and be ready for a little bushwhacking.
We want to express our immense gratitude to all those who have Supported ESAC this season. Thank You!