The NAVGEM and GEM are great! With all the cold air coming over to the atlantic side, some unseasonably low uppers could get towards the UK in this cold snap.
Now the SSTs are still very high at this time of year
http://www.bsh.de/aktdat/mk/nordsee/actual.gif
and are, roughly about average for the time of year.
I think I said a while back how heavy snow is much easier to get early on. This is a pretty good example:
if -10C uppers were to get down across the north sea coasts generally, with a 10C ocean, that is a 20C gradient to the 850 level. Now, you generally need 13C gradient to initiate lake effect precipatation, above 17C and you can get some really quite heavy showers. And above 21C thundersnow becomes common. It is quite concevable that some northern areas will meet this benchmark with uppers perhaps as low as -13C in the far north, and -11 or -12 more generally; giving perhaps a maximun of a 22C temp gradient.
A 22C temp gradient, would be capable of producing 10cm/h + rate snowfalls. Note, I am not saying 10cm will fall every hour, but the core of the showers could be well above a 10cm/h rate, even perhaps getting into the 20s in the heaviest showers. And we might also expect to see lifted indicies getting towards zero. Thundersnow would be on the cards if everything else plays right (the wind is perhaps too northwesterly, a slight easterly component is probably needed).
http://www.meteociel.fr/modeles/gfse_cartes.php?mode=11&ech=204
Indeed, look at the 216 chart and notice the blues.
I made a thread a while back where I looked at observed values of CAPE in lake effect snow for the UK. You need a cape of about 150j/kg - 200j/kg for thundersnow. That is somewhat evident here.
Twitter: @QuantumOverlord (general), @MedicaneWatch (medicane/TC stuff)
2023/2024 Snow days (approx 850hpa temp):
29/11 (-6), 30/11 (-6), 02/12 (-5), 03/12 (-5), 04/12 (-3), 16/01 (-3), 18/01 (-8), 08/02 (-5)
Total: 8 days with snow/sleet falling.
2022/2023 Snow days (approx 850hpa temp):
18/12 (-1), 06/03 (-6), 08/03 (-8), 09/03 (-6), 10/03 (-8), 11/03 (-5), 14/03 (-6)
Total: 7 days with snow/sleet falling.
2021/2022 Snow days (approx 850hpa temp):
26/11 (-5), 27/11 (-7), 28/11 (-6), 02/12 (-6), 06/01 (-5), 07/01 (-6), 06/02 (-5), 19/02 (-5), 24/02 (-7), 30/03 (-7), 31/03 (-8), 01/04 (-8)
Total: 12 days with snow/sleet falling.