Areas shaded pink have been issued a winter storm warning, areas shaded purple have been issued a winter weather advisory. photo: NOAA
Probability for snowfall exceeding 6 inches for the 24-hour period ending at noon on Tuesday. photo: NOAA
Portions of the Eastern Northern Rockies and the Little Belt Mountains in Montana have been issued a Winter Storm Warning. Large areas of the Rockies, South into Wyoming and West into Idaho have been issued a winter weather advisory. The forecast calls for 6-10 inches above 5,000 feet before Tuesday at 6pm. Areas outside of the winter storm warning area should still expect snow! Big Sky, in the Gallatins, is forecasted to receive up to 7 inches of cold new snow for Tuesday morning, with cold temperatures continuing throughout the week.
Jackson Hole is about to get hit (again) by this storm, which could drop up to 11 inches by Tuesday morning. Grand Targhee is expecting similar totals by Tuesday morning. Temperatures in the area should remain cold throughout the week, preserving the new snow. Conditions should remain excellent in the Rockies for the next week, or until temperatures increase.
While the snow forecast looks very enticing, the new snow is falling on top of a very unstable snowpack. In the past 10 days there have been two avalanche deaths and two serious injuries in Montana and Wyoming alone. While the new snow will present a hazard, weak layers remain buried in the snowpack.
“A more complex problem is triggering avalanches that break on deeper layers in the snowpack. Facets buried mid-pack and near the ground still hold the potential to propagate fractures and produce large avalanches (photo, photo). These types of avalanches will be easiest to trigger in steep, rocky terrain where the snowpack is thinner.” mtavalanche.com
While this statement applies to current conditions in Montana, it is important to consider the snowpack composition throughout the Rockies.