SKILLFUL LONG-RANGE FORECASTS OF NORTH AMERICAN HEAT WAVES FROM PACIFIC STORM PROPAGATION

June 22, 2017

Andrea Jenney

Committee: David Randall (advisor), Elizabeth Barnes, Brooke Anderson (Environmental and Radiological Health Sciences)

Abstract

Extreme heat poses major threats to public health and the economy. Long-range predictions of heat waves offer little improvement over climatology despite the continuing improvements of weather forecast models. Previous studies have hinted at possible relationships between tropical West Pacific convection and subsequent anomalous near-surface air temperature and rainfall over the North American Plains. We show that the later stages of propagation of the Boreal Summer Intraseasonal Oscillation (BSISO) can be used to skillfully hindcast a number of Great Plains heat waves between 1948 and 2016 with a three-month lead time. Possible teleconnection mechanisms are investigated, with the most likely being related to a BSISO-induced reduction in Plains spring rainfall and subsequent land-atmosphere feedbacks. Our results are the first to demonstrate that a West Pacific weather event can be used to skillfully forecast US Plains heat waves with a lead time of three months.