Mini-vortex over the southwest

Figure 1

The Caribbean will shortly have the intense vortex of Hurricane Irma to contend with, but we have our own interesting mini-vortex across the southwest of England this morning. It doesn’t seem that noticeable in the plotted synoptic chart (fig 1), but you can easily identify it in visible satellite imagery (fig 2), and to some extent the decaying spiral rainbands in the weather radar (fig 3).

Figure 2
Figure 3

I tried to analyse the frontal position on the 09 UTC chart as you probably noticed (fig 1), albeit with a little help from the visible satellite image. The only trouble with that approach is that you end up with a nephanalysis and not a surface analysis, talking of which here is the 06 UTC analysis from the Met Office looked like (fig 4), even before I downloaded it I suspected that an upper cold front would be part of the answer!

Figure 4 – Courtesy of the Met Office