WINTER SEASONAL CLIMATOLOGY, VARIABILITY, AND PREDICTION OF NORTHWEST ATLANTIC EXTRATROPICAL CYCLONES

Abstract

Winter Extratropical Cyclones (ETCs) are mid-latitude storms that regularly impact the east coast of North America. These storms are characterized by high winds and heavy precipitation (rain, snow, and ice). ETCs are well predicted by NWPs at short- to mid-range forecast lead times (up to 5 days) however, on seasonal time scales these storms are not well predicted. The goal of this thesis is to first understand and then predict the seasonal variability of winter ETC activity along the east coast of North America. It begins with creating a dataset of ETCs from ERA5 mean sea level pressure. After calculating the climatology, the spatio-temporal variability of the dataset is analyzed to draw out the dominant patterns and trends. The covariability between storms and regional atmospheric variables is then examined to look for large scale forcing patterns. Those relationships form the basis of a set of storm type-specific multiple linear regression prediction models. This set of models is applied in a probabilistic forecast framework that predicts characteristics of the winter season experienced in Halifax, Nova Scotia, Canada.