Snow Assessments

2017 Snow Assessment


Aaron Letterly
10 June 2018

Northern Hemisphere Seasonal Snow Depth Anomalies


Snow depth anomalies derived from the Canadian Meteorological Centre (CMC) daily gridded snow depth analysis (Brasnett, 1999) show the seasonal development of terrestrial, hemispheric snow depth from December 2016 to November 2017 (Figure 1). In December-February, snow depth in Eastern Siberia was more than 35 cm above the 1998-2017 climatological average, but was below average along the North American Pacific Coast Ranges and northern European Russia. Most of the regions that experienced negative snow depth anomalies in the winter experienced positive snow depth anomalies (more snow than usual) in March-May. The southern Pacific Coast Range and Kamchatka Peninsula, however, had lower snowfall depths than normal during the 2017 spring. By June-August, the only positive snow depth anomalies of note were in the Canadian Archipelago along Baffin Bay and in the Himalayas (which show a positive snow depth anomaly all year). Negative snow depth anomalies from the spring seemed to persist into summer in the Pacific Coast Range and parts of Kamchatka. From September-November, negative anomalies deepened in Southern Alaska and Northwest Canada, while snow depths were above average in Eastern Canada and much of Siberia.

Figure 1
Figure 1: Mean of 2017 seasonal snow depth anomalies for three-month periods in the Northern Hemisphere. Greenland and marine snow depth anomalies were screened out at the suggestion of the data provider. Data are from the National Snow and Ice Data Center (NSIDC).

Analysis of the snow depth anomalies in Baffin Bay between 2016 and 2017 show a significant decrease in snow depth over the course of the year. The north-south crescent of large islands that skirt the northern and western sides of Baffin Bay are Baffin Island, Devon Island, and Ellesmere Island. The rocky, mountainous eastern coasts of these islands saw positive snow depth anomalies (greater than 35 cm) in spring of 2016 decrease to average snow depths in late 2016. By spring of 2017, the snow depth along the entire coastline was more than 35 cm below average. The beginning of winter 2017 showed negative snow depth anomalies had advanced further inland on the islands towards higher elevations, meaning much shallower snow on the western coast of Baffin Bay than the 1998-2017 average.

Figure 2
Figure 2: Mean of 2016-2017 seasonal snow depth anomalies for three-month periods showing rapid changes along Baffin Bay. Data are from the National Snow and Ice Data Center (NSIDC).

References

Brasnett, B. 1999. A global analysis of snow depth for numerical weather prediction, Journal of Applied Meteorology 38:726-740.

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