Blocking?

[liam300]

Hi,

im relatively new here, their are a lot of discussions regarding blocking and have a lack of knowledge towards this.

Can somebody explain.

Many Thanks

[snowstorm445]

Blocking, in the broadest definition, is when an area of stationary high pressure disrupts the usual atmospheric air currents. In terms of this part of the world, an area of blocking would disrupt the Jet Stream's usual West-East pattern. The Jet Stream usually brings us fairly unsettled conditions, including low pressure systems which usually bring us rain. It also brings us westerly winds, and depending on how powerful the Jet is, the winds tend to vary in strength.

In an area of blocking, the Jet Stream is displaced. During winter, blocking can push the Jet Stream south, bringing most the rain that we would usually get to the Mediterranean, and as a result, being on the colder side of the Jet Stream, we can see colder winds coming down from the north or east. In summer, if the Jet Stream is pushed northwards, we can see warm air from the tropics being pumped up over us, giving us fine dry weather.

Its quite difficult to summarise it in short, but that is basically all there is too it. There are many factors that determine the probability of blocking, including NAO, the Polar Vortex, the AO etc.

[lorenzo]

Haby Hints has a good page, lots of other weather Q's answered here too..

http://www.theweatherprediction.com/blocking/

[liam300]

Thanks a lot guys,