An observational analysis: Tropical relative to Arctic influence on midlatitude weather in the era of Arctic amplification

The tropics, in general, and El Niño/Southern Oscillation (ENSO) in particular are almost exclusively relied upon for seasonal forecasting. Much less considered and certainly more controversial is the idea that Arctic variability is influencing midlatitude weather. However, since the late 1980s and early 1990s, the Arctic has undergone the most rapid warming observed globally, referred to as Arctic amplification (AA), which has coincided with an observed increase in extreme weather. Analysis of observed trends in hemispheric circulation over the period of AA more closely resembles variability associated with Arctic boundary forcings than with tropical forcing. Furthermore, analysis of intraseasonal temperature variability shows that the cooling in midlatitude winter temperatures has been accompanied by an increase in temperature variability and not a decrease, popularly referred to as “weather whiplash.”