Atmospheric blocking is a meteorological phenomenon where a large-scale, nearly stationary high-pressure system (also called a blocking high or anticyclone) disrupts the typical west-to-east movement of weather systems, causing stagnation of weather patterns for an extended period—often several days or even weeks.[1][2][3]
How Blocking Works
A blocking pattern acts like a roadblock in the atmosphere. Normally, jet streams push weather systems steadily eastward, but when a persistent high-pressure area forms in the jet stream’s path, it causes these systems to slow down, stall, or be diverted around the block. As a result, the regions beneath the block experience consistent weather—such as dry, warm conditions under the high, or prolonged rain and unsettled weather where systems become stuck at the edge of the block.[2][3]
Types of Blocking Patterns
- Omega block: Shaped like the Greek letter Ω, with a central high flanked by two low-pressure systems, forcing the jet stream to curve around it.
- Rex block: Features a high-pressure system directly north of a low-pressure system, splitting the jet stream and impeding normal flow.[3]
Impact and Significance
Blocking events are responsible for extreme weather such as heatwaves, cold snaps, droughts, or persistent rainfall. Their persistence and scale mean that affected areas can endure the same conditions much longer than usual, increasing risks for agriculture, water supply, and public safety.[4][1]
Challenges in Forecasting
Forecasting the formation, duration, and decay of blocking events is challenging due to their nonlinear dynamics, large scale, and sensitivity to initial atmospheric conditions.[1][3]
Atmospheric blocking is a critical factor in explaining prolonged or extreme weather events and is an area of active meteorological research.[3][1]
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- https://en.wikipedia.org/wiki/Block_(meteorology)
- https://weather.metoffice.gov.uk/learn-about/weather/how-weather-works/high-and-low-pressure/blocks
- https://climate.sustainability-directory.com/term/atmospheric-blocking/
- https://www.climatesignals.org/climate-signals/atmospheric-blocking-increase
- https://www.sciencedirect.com/topics/earth-and-planetary-sciences/atmospheric-blocking
- http://www.theweatherprediction.com/blocking/
- https://weather.missouri.edu/gcc/Lupo-blockreview.pdf
- https://wcd.copernicus.org/articles/3/305/2022/
- https://www.sciencedirect.com/science/article/pii/S2212094722000858
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