Areas of high pressure can sometimes be very slow moving, almost stationary. Such a region of slow moving air can prevent other, faster moving pressure systems from moving into a region. For this reason they are known as blocking highs or blocking anticyclones.
The part of the earth’s surface beneath a blocking high often experiences the same kind of weather for a long period (perhaps as long as several weeks). In Europe, for example, blocking highs over Western, Russia, Eastern Europe and Scandinavia have caused long, severe winters (see chart). Blocking highs have also led to prolonged droughts.