Influence of low frequency variability modes on spatiotemporal patterns of temperature and precipitation in Northwestern North America

Abstract

ABSTRACT This study performs a comprehensive analysis of the influence of low-frequency variability modes (LFVMs) on the average and extreme temperature and precipitation in the extended winter (November–February) over Northwestern North America (NWNA). Maximum covariance analysis is applied to quantify the covariability between LFVMs and regional climate variables, followed by composite analysis to assess the influence of each LFVM on extremes at local scales using high-resolution gridded observations. This study extends previous analyses by characterizing the spatial patterns of regional climate variations associated with a suite of LFVMs. This includes the associations between negative phases of North Atlantic Oscillation (NAO) and extreme precipitation over western NWNA and the central Columbia basin and the positive phase of the North Tropical Atlantic (NTA) with increases in the minimum and maximum temperature of NWNA except for the western Fraser basin. Overall, the analyses show that LFVM effects are more pronounced over the eastern and southcentral parts of NWNA during extended winter.