Paralysing January 1999 Snowstorms Produced Minimal Streamflow for Southern Ontario

Abstract

On January 2, 1999, the city of Toronto and surrounding regions of southern Ontario, Canada were brought to a standstill by a large storm event that resulted in near–record snowfalls. Several smaller winter storms followed and by January 15 approximately 100 cm of snow had fallen across the area, creating a flooding concern for water resources managers. A statistical analysis of the 1999 snowpack depth and snow water equivalent (SWE) for the Grand River Basin showed that the snow depths were the largest on record with two–week snow depth increases at several sites having return periods from 50 to 200 years. However, the amount of water in the snowpack was small, with the return period for SWE being between two and 21 years. Above freezing temperatures occurred in mid–January partially melting the pack and producing some streamflow. No flooding occurred, and the spring peak streamflows were amongst the lowest on record. © 2004, Taylor & Francis Group, LLC.