A Big Anniversary

Tomorrow marks the 10th anniversary of the start of the 2001 Hundred Inch Storm, a multiday storm cycle that laid down 108 inches of snow at Alta, including 100 inches during a 100 hour period.  If memory serves me correctly, there was little snow leading up to Thanksgiving weekend that year, so the snow answered the prayers of desperate Utah skiers who were burning their rock skis as a sacrifice to Ullr to bring snow.

As described in Steenburgh (2003, 2004), the Hundred Inch Storm provides a great example of what Mother Nature can do when the atmosphere and Great Salt Lake are in outlier mode.  It was produced by two storm systems that were strongly augmented by the Great Salt Lake Effect.  Each storm system featured a period of stable, pre-frontal precipitation, a period of unstable pre-frontal precipitation that followed the surge of cold, dry air aloft, heavy frontal precipitation accompanying the cold front, and then intense lake-effect snowfall.

Radar imagery from storm system I showing stable prefrontal
(top left), unstable prefrontal (top right), frontal (bottom left),
and lake-effect (bottom right) stages.

Radar imagery from storm system II showing stable prefrontal
(top left), unstable prefrontal (top right), frontal (bottom left),
and lake-effect (bottom right) stages.

Most remarkable about this event was the intensity and duration of the lake-effect precipitation, which produced 2.18 inches of snow water equivalent at Alta-Collins.  Kristen Yeager shows in the MS thesis that she will defend next week that the two lake-effect periods are extreme outliers during the 1998–2009 radar record.

The bottom line is that the 100-inch storm was a whopper of an event, especially with regards to lake-effect, and we haven't had anything like it since.