New research gives an indication of the amount of summer precipitation in Northern Europe

Researchers at SMHI have found a teleconnection between the atmospheric conditions over the subtropical Pacific during spring and summer precipitation in the Northern Europe. This discovery creates the prerequisite for a simple, yet relatively accurate, estimate of summer precipitation several months in advance.

“We can show that subtropical atmospheric variability over the subtropical Pacific modulates the circulation over the western Arctic and the North Atlantic-European sector. This has an impact on the summer precipitation, especially over the Northern European countries,” says Ramón Fuentes Franco, researcher at SMHI's Rossby Center.

In recent years, several different research groups have studied different teleconnections that can explain the weather over northern Europe, in order to improve the possibility of making reliable seasonal forecasts for this area. Until now, however, it has been a challenge to understand which processes affect the variation in summer precipitation across Europe.

“By knowing the state of the atmosphere over the subtropical Pacific in early spring, in March, we get the possibility to draw conclusions of whether the summer season over the Northen Europe will be drier than normal, normal or wetter than normal,” says Ramón Fuentes Franco.

Indicates amount of summer precipitation

Indikation of summer precipitation June-August 2020
The new knowledge of the teleconnection between the atmospheric conditions over the subtropical Pacific in March and rainfall in the Northern European countries during the summer (June-August) indicates a summer with mostly normal precipitation. Map colours: Orange - less precipitation than normal, yellow - normal, green - more precipitation than normal. Enlarge Image

With this new knowledge, researchers can explain about 40 percent of the total variation in summer precipitation.

Based on the new knowledge presented, which conditions can be expected for the coming summer?

“Based on this new research, we could expect slightly drier conditions than normal in the North, but on the whole it seems to become a normal summer when it comes to rainfall,” says Ramón Fuentes Franco, who also emphasizes that the results should not be taken as a deterministic forecast since the relationship is not linear and can change in the future.

Facts: Teleconnections

A connection in the weather between two areas that do not have a direct geographical connection is called teleconnection. An example is the PNA, the Pacific-North American teleconnection pattern, which can explain ENSO's influence on the weather in the United States.

Another example of a teleconnection is the North Atlantic Oscillation, NAO. It is a link between pressure conditions in the atmosphere between Iceland and the Azores, which affects large-scale weather patterns across Europe.