Mon, May 10, 2021 at 3:50pmIssued by: Mike Floyd
Storm snow totals in the Front Range will be over a foot in many areas by Tuesday afternoon. You can easily trigger avalanches on steep slopes where there is more than about 8 inches of storm snow. These will run on old frozen crusts and could be large enough to bury you completely. Storm snow and wind slab avalanche problems transition to wet avalanche concerns late Tuesday and Wednesday. Expect some avalanches to run naturally, especially if the sun makes an appearance.
A trough of low pressure over the Great Basin is driving weather across Colorado Monday afternoon. Banded precipitation transitions to convective snow showers Monday afternoon. These favor the Northern and Central Mountains with 3 to 6 inches of snow possible by Tuesday morning. The Southern Mountains will not see appreciable snowfall.
Snowfall continues along the Front Range into Tuesday morning, aided by upslope easterly winds and abundant moisture. 6 to 10 inches of snowfall with localized amounts over a foot does not seem unrealistic, especially above treeline. Some snowfall spills further west to the Mosquito and eastern Sawatch Ranges, with a few inches possible Tuesday morning. High temperatures will be in the 30s Fahrenheit across the North, with 40s common in the South. Snowfall ends with gradual clearing Tuesday night and lows in the 20s. Temperatures gradually warm through the rest of the week as a breezy northwesterly flow becomes more westerly.
Snowpack and Avalanche Discussion
Tuesday starts cold and snowy, with storm snow avalanches as the primary problem on your radar. Look for deeper areas of wind-drifted snow as possible trigger points, especially on slopes steeper than 30 degrees. You are most likely to encounter this problem at upper elevations where there is a firm, frozen surface underneath. As the storm winds down and temperatures rise, watch for rapidly increasing instability. If you see natural wet avalanches or snowballs rolling out of steep, rocky areas, this is a good indicator that instability is increasing. If the sun comes out, this could happen in a matter of minutes. To mitigate wet avalanche concerns, start and end your day early.