Note on the Modis image there appears to be
another similar pattern developing in the cloud to the south south west.

No evidence of vorticity at the surface on these hourly plots:

Karl, Orkney, Scotland
Processing the image shows the second vortrex well and the extensive gravity
wave activity in the area.

I would suggest this is the expression of a PV streamer and vortex (-ices)
seen in the 12Z WV image-

http://www.sat.dundee.ac.uk/pdus/BW/...51200BW1_g.jpg

Soundings at both Trappes and Merignac show the dry air aloft due to the PV
intrusion-

http://weather.uwyo.edu/cgi-bin/soun...512&STNM=07145

http://weather.uwyo.edu/cgi-bin/soun...512&STNM=07510

PV streamers have been called 'tropospause shear lines' which suggests how
vortex spin up can occur along them.Unusual appearance in this case
though.Is the central white area caused by convection or convective
overturning (?),

regards,
David