Weatherwatch: heatwaves and atmospheric blocking

An occasional series on weather terminology: stationary areas of pressure can lead to prolonged heatwaves and cold spells

The “beast from the east” cold of late winter 2018 and the arid heat of the UK’s summer so far, are united by one pronounced meteorological phenomenon: atmospheric blocking. Large meanders in the jet stream often lead to the development of huge anticyclones – areas of high pressure that can remain stationary for weeks at a time.

A blocking area of high pressure, sitting over Scandinavia and western Russia in February and early March, maintained a static weather pattern and pulled in a conveyor of sub-zero air to the UK. Just four months later, blocking allowed high pressure to settle close to the UK. This has resulted in very warm and extremely dry conditions with some central and southern parts of the UK seeing no measurable rain for over a month.

Predicting when and where atmospheric blocking will take place is difficult, although there are some clues. One signal is solar activity, the levels of radiation, sunspots and other solar phenomena that ebb and flow on a periodic 11-year cycle. Studies have shown that, on average, a decrease in solar activity can promote an increase in atmospheric blocking, although the relationship is complex.

Brendan Jones (MetDesk)

The GuardianTramp

Related Content

Article image
Weatherwatch: sudden stratospheric warming and the Beast from the East
The first in an occasional series on meteorological terminology: a look at the atmospheric conditions behind the late cold snaps that interrupted spring

Michael Dukes (MetDesk)

19, Mar, 2018 @9:30 PM

Article image
Weatherwatch: May 1935 saw unusually wintry conditions
Widespread frost caused damage to fruit and vegetables as temperatures plunged

Stephen Moss

02, May, 2018 @8:30 PM

Article image
Weatherwatch: is March a lion or a lamb?
With March on the cusp between two seasons, it is not surprising its weather is unpredictable

Stephen Moss

07, Mar, 2018 @9:30 PM

Article image
Weatherwatch: 1940 Ice Storm added to misery of war
January 1940 was coldest month on record for almost 50 years, freezing the river Thames

Stephen Moss

26, Jan, 2018 @9:30 PM

Article image
Weatherwatch: cold-water swimmers brave icy conditions
Outdoor swimming is said to have many health benefits, including the chronic pain cured by dip in the sea

Jeremy Plester

05, Mar, 2018 @9:30 PM

Article image
Weatherwatch: the 'halcyon days' of December hark back to the kingfisher
This shy little bird is linked to many bizarre beliefs about the weather

Stephen Moss

12, Dec, 2017 @9:30 PM

Article image
Weatherwatch: golf ball-sized hailstones rain down on Bavaria
Heatwaves in Poland led to 33C temperatures while severe floods in China caused landslides

Daniel Gardner (MetDesk)

19, Jun, 2019 @8:30 PM

Article image
Weatherwatch: La Niña strikes out on its forceful voyage round the globe
Unusually cold patches of the Pacific ocean are again on the move, threatening to disrupt weather patterns worldwide

Jeremy Plester

16, Nov, 2017 @9:30 PM

Article image
Weatherwatch: rainbows with added heart-lifting value
June is a prime month for spotting rainbows, even a double or one with multiple supernumerary arcs

David Hambling

31, May, 2019 @8:30 PM

Article image
Weatherwatch: rare atmospheric river caused UK flooding
Floods in Wales were brought by an unusual front that moved from south to north, sucking in moist air from tropical Atlantic

Jeremy Plester

17, Oct, 2018 @8:30 PM