Regional patterns of temperature and precipitation for Newfoundland and Labrador during the past century

We have analyzed the mid-to-late 20th century instrumental record of winter and summer temperatures and precipitation for six stations representative of Newfoundland subregions and of central and coastal Labrador. In addition , these modern records have been extended into the 1800s by using portions of records from Belie isle and the city of St. John's. For these two length ier records, several 'epochs' of alternating relatively high or low charact eristic temperatures are distinguished, particularly for the winter season. The modern (post-1940) temperature records show that the mid-century warm period has been succeeded by a significant shift to predominantly colder wi nters over this entire region since about 1972. A concurrent decline in sum mer temperatures is restricted to Labrador and north-central parts of the i sland. With respect to other studies of recent climatic trends over northea stern Canada and the northwest Atlantic, our results demonstrate a signific ant correlation, at most of our study locations, between mean winter temper ature and seasonally averaged values of the North Atlantic Oscillation (NAO ) and the Baffin island-West Atlantic Index (BWI). Comparative examination of the precipitation record for these stations also reveals subregional scale contrasts in the degree of variability and trend for annual and seasonal totals. For St. John's, representative series of t otal precipitation spanning the past century are analyzed for winter and su mmer; these series lack significant lengthy trends, although short-term pre cipitation variability is to some degree associated with the mean temperatu res of the defined epochs. Since the 1940s, significant upward trends in to tal amounts and frequencies characterize the southwestern coast of the isla nd for both winter and summer, and eastern Labrador in summer. The increase d winter snowfall observed on the southwest coast during the past three dec ades is considered to be linked to a greater frequency of onshore synoptic airflow patterns accompanying the trend to predominantly positive winter NA O Index within this period.