This winter has for the most part been dominated by an active zonal flow which in essence means the weather has come from the west and as most of you will know when this occurs, wet and windy weather will be the main feature in such a flow.

 

This flow has unfortunately led to floods across the UK with these certainly more apparent recently especially across parts of Wales and the Midlands. Our own re-analysis highlights the fact that many western areas have indeed been far wetter than is the norm.

 

So the question for many will be why? Why has the pattern been so dominant? For the answer we have to look way up in the stratosphere.

 

Early in winter things looked very different indeed, the vortex was weak and the troposphere was completely disconnected from the stratosphere. However the stratosphere rapidly recovered around mid-December and ever since then the Polar Vortex has been stronger than normal. The graph below shows this well with the vortex currently off the scale.

 

The next image below is the current winds at 10hpa, again in the Stratosphere. Just look how circular the winds are, a good testament to a strong vortex and this is effectively locking all the cold air with the Arctic region.

 

A strong vortex will drive the weather further down in the troposphere which effectively means the westerlies become dominant.

 

An example of this would be the winter of 2013-14 where again the vortex was very strong. Flooding was also an issue through that winter. The 500mb re-analysis chart shows the deep blue colours which represents lower than normal heights.

 

Lower than normal heights essentially equate to low pressure and though that winter low pressure was very dominant as was the westerly flow.

 

Unfortunately there seems very little signs of change at the moment but if you want more detailed analysis and forecasts head on over to the Real Weather Pro Group and follow the instructions.

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