A climatology of adverse winter-type weather events

Stephen J. Déry and M. K. Yau


A global and regional climatology of three adverse winter-type weather events is presented.Using the European Centre for Medium Range Weather Forecasts (ECMWF) Re-Analysis (ERA) gridded data, a global compilation of blowing snow, blizzard and high windchill events is conducted for the period1979-1993. The results show that these phenomena occur primarily over flat, open surfaces with long seasonal or perennial snowcovers such as the Greenland and Antarctic icefields as well as the Arctic tundra. On a regional scale, emphasis is given to the Mackenzie River Basin (MRB) of Canada where fewer events take place within the boreal forest as opposed to the Arctic tundra. Interannual and monthly variabilities in the number of events are also evident and are due primarily to 10-m wind speed anomalies at high latitudes for blowing snow and blizzard events while high windchill events are more sensitive to air temperatures near the surface. We also find that high windchill episodes are the more frequent events since they occur at 9.5% of all possible grid points and times on a yearly basis, while blowing snow at 7.4% and blizzards at 2.3% are less common events. Compositing of principal meteorological fields show that anticyclones and lee cyclogenesis are prominent features associated with blowing snow events in some sections of the MRB.