The Effect of Protracted Spring Thaws on Ice Conditions in Hudson Bay *

Abstract

The extent of ice cover in Hudson Bay was investigated during the Spring of 1948 by the RCAF and interested governmental departments. A series of reconnaissance flights over the Bay in March and April disclosed that it was virtually ice-bound from shore to shore. Large areas of open water were observed during the period May 3rd to May 6th. An inspection of the synoptic weather charts disclosed that weather conditions over the Bay both prior to and during this period were abnormal. This immediately suggests that the ice conditions observed might not be representative. For an appraisal of the observations it is necessary to determine the effects of the abnormal weather on the ice. The observed ice conditions are mentioned and the causes of open water areas briefly discussed. The severity of the winter at Churchill was investigated to determine the normalcy of the ice development. A protracted thaw over the eastern parts of Hudson Bay is disclosed by reference to the weather charts. The correlation between the mean monthly temperatures for the spring months and the date of ice clearance at Churchill Harbour is then investigated to determine the effects of a protracted thaw on the ice.