Friday, April 16, 2010

Dirty snow means a quick melt

I was able to get up into the high country this week. The day was warm, the sky was blue and the snow was covered with red dust. This is not the pink snow of bacterial fame, but snow that is covered with the red dust of the Utah and Arizona deserts. The week before we had had some powerful "wind events". There was a record report of winds at Red Mountain Pass at almost 90 mph. These spring winds not only do an efficient job of melting back (or I guess I should say sublimating) the snow. We lost 12% of the snow pack in just a few days. The winds also drop dust particles from the desert onto the snow. Studies have shown that this dirty snow will melt at a much faster rate than clean snow. A recent article in the aspen times discusses this effect.

As the climate changes, models suggest that the American Intermountain West will become warmer and dryer. A warmer and drier desert could provide even more dust in future years. The snow pack, which might be less than average, will melt even faster. No matter why the climate is changing I think we need to start thinking about how we can best survive these changes.

A dirty hillside. Looking towards Hayden Peak.

The north facing slope is still white from new snow on top of the dust. The south facing slope shows the extent of dust as the newer snow has melted.
Snow shoe tracks showing clean snow below the dusty layer.

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