The Surrey Hills saw some significant snowfall today, almost 10cms here at Woodhill Cottage, but this may just be part one. The chain of events that has led to this weekend's weather started just after Christmas with a Sudden Stratospheric Warming (SSW) event over the Arctic. Sudden Stratospheric Warming is a rapid warming (up to about 50c in a couple of days) of the air in the stratosphere, that eventually leads to disruption of the jet stream. Adam Scaife of the Met Office explains in more detail in the below video. In short SSW events lead to high pressure over the North Atlantic 'blocking' the mild air and the low pressure systems that brought us all that rain over Christmas. This SSW event has resulted in high pressure over Sweden which is bringing us a cold easterly wind from the continent. The low pressure systems that are doing battle with this cold air are losing and their rain is turning to snow. Today's low came from the west and Wales got hit hardest. On Sunday a low will push up from France and when it hits that cold air the South East may be in for another 10-15cms. The weather bloggers are calling it Snowmageddon. I say sledgetastic.