Blocking Highs.

How does snow grow? …

Cyclones run anticlockwise. Anticyclones run clockwise. When two such air masses (Low and High pressure areas) sit side by side they interact to produce winds flowing in much the same direction.

If the High is on the western side and the Low to the east. The effect is to draw down winds from the north to the longitude between them.

Appologies for poor ASCII art:

(o)V V(o)
. . V V

Sorry about that. Here is a recent chart:

It is still a litttle complex but as it settles down, according to more reasoned forecasters, the High over the Greenland region will react with the Low over Scandinavia to produce a decent snowfall in Britain.

Or not, as the case may be.

The reason the high is called a blocking high is that it stops the normal run of events of Atlantic storms running from Canada to Norway. Wouldn't you think that since there is a super abundance of low pressure moving towards it, the High would be quickly deflated.

And yet it is quite a long stayer. Methinks something stinks on its way to ermm… not Denmark… erm not Norway too, neither, this week.


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