LAKE SUPERIOR AREA TEMPERATURE VARIATIONS∗

Abstract

Variations in atmospheric circulation and spatial and temporal patterns of sea-level pressure anomalies over eastern North America are highly correlated in time with temperature trends in the Lake Superior area. Lake Superior region temperature trends have not been the same for all seasons. January and July temperatures were highest in the mid-1930s; those for April and October culminated later. Differences in the timing of temperature peaks within the Lake Superior region are related mainly to variations in pressure anomalies over western Canada and with associated anomalous air flow components across the Lake. Pressure anomalies over the southwestern United States and opposite anomalies to the east have been less important and they have affected mainly the temperatures over the eastern part of the region. About seventy to eightly percent of the temperature variance for the Lake Superior region is related to about twenty-five to thirty percent of the pressure variance for eastern North America.