New research shows that two specific jet stream configurations are responsible for heatwaves lasting two weeks or more across western Europe. The findings come from analysis of climate model simulations and could improve forecasting of extended hot spells.
Scientists at the University of Bern identified the patterns by studying 1900 simulated long heatwaves. In type I events, the jet stream forms an omega-shaped kink that traps high pressure over the region. Type II events involve a poleward shift of the jet stream that diverts storms northward while allowing warm air to flow in from the south.
The study notes that Europe's June heatwave, which killed an estimated 20,000 people, began as a type II pattern before shifting to type I. The current heatwave largely matches the type I configuration, according to researcher Duncan Pappert.
Forecasters could use these patterns to give earlier warnings, allowing power grids and other infrastructure to prepare for sustained high demand. The research appears in Environmental Research Letters.
