Persistent Cold Weather Events in the Central-Eastern North America

The circulation patterns for persistent cold weather events for eastern US and Canada ( 95W-65W, 32N-52N) are investigated using NCEP Reanalysis(1948-2014) and ERA-Interim(1979-2014). The criteria for the persistent cold events are: 1.The three day averaged temperature anomalies for the regional average over eastern US and Canada are below 10th percentile; 2. Such extreme "cold spells" last at least 10 days. The circulation patterns associated with these cold events are examined closedly to find common factors which are preludes of these events. The circulation anomaly patterns of these events are categorized based on the El Nino-Southern Oscillation (ENSO) indices, Pacific Decadal Oscillation (PDO), Arctic Oscillation (AO) indices, and other climatic patterns from PCA(EOFs). Atmospheric circulation patterns and factors in lower boundary favor these cold events are identified through the composites of the cold events. The differences of stationary wave pattern and wave sources before and during these cold events in different background atmospheric circulations and boundary conditions are investigated.