There was snow with thunder and lightning in Stornoway today (21 December 2016). It was captured by the Stornoway Lews Castle College radar (see below):
#thundersnow occurred just after 16h: See the bright red colour (top right image) & pink (bottom left), as well as large vertical velocity Doppler shifts (shades, bottom right). These are indicative of large hail, large snowflakes and considerable turbulence respectively, leading to the exchange of electrical charge. You can learn more about what the colours mean here: https://uhi-mahara.co.uk/view/view.php?id=24843
Known as 'thundersnow', it is a common misconception that thunderstorms require heat and warm weather for their development. This is a false premise: What thunderstorms really need is atmospheric instability, which is a frequent occurrence in deep cold polar airflows over warm ocean surfaces, such as happens fairly often in NW Scotland during wintertime.
@eddy_weather, Stornoway, 21 Dec 2016