Seeing ships in rain radar

I’m starting to play around with “nowcasting” – doing weather forecasts based on recent rain radar images.  The Met Office provides a feed of radar images you can get from their Datapoint service.

The first plot I made of the data was number of rainy 15 minute periods during May (shown with and without a base map):

rawradar radarandbase


There are many interesting features here.  Firstly a few probably true observations about rain:

  • You can clearly distinguish land and sea – there is more rain over land.
  • You can see hilly regions with yet more rain.

However there are many other features that I guess aren’t true observations about rain:

  • You can see the two shipping lanes in the English Channel with the separation zone between them.
  • You can see the individual radar sites don’t give uniform coverage in all directions.
  • There are other linear features of which I’m not sure of the origin – any ideas?

All these features suggest that I can’t treat this data as perfect truth data for nowcasting.  😦