Warm Arctic episodes linked with increased
frequency of extreme winter weather in the United
, Karl Pfeiffer
& Jennifer A. Francis
Recent boreal winters have exhibited a large-scale seesaw temperature pattern characterized
by an unusually warm Arctic and cold continents. Whether there is any physical link between
Arctic variability and Northern Hemisphere (NH) extreme weather is an active area of
research. Using a recently developed index of severe winter weather, we show that the
occurrence of severe winter weather in the United States is signiﬁcantly related to anomalies
in pan-Arctic geopotential heights and temperatures. As the Arctic transitions from a rela-
tively cold state to a warmer one, the frequency of severe winter weather in mid-latitudes
increases through the transition. However, this relationship is strongest in the eastern US and
mixed to even opposite along the western US. We also show that during mid-winter to late-
winter of recent decades, when the Arctic warming trend is greatest and extends into the
upper troposphere and lower stratosphere, severe winter weather—including both cold spells
and heavy snows—became more frequent in the eastern United States.
Atmospheric and Environmental Research, Lexington, MA 02421, USA.
Department of Civil and Environmental Engineering, Massachusetts Institute of
Technology, Cambridge, MA 02139, USA.
Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ 08901, USA.
Correspondence and requests for materials should be addressed to J.C. (email: firstname.lastname@example.org)