Tuesday 8th January 2013

Rule number one in weather forecasting - if models are showing easterly winds, always take them with a pinch of salt. If models are predicting a westerly wind 10 days out then it will almost definitely happen - if they are showing an easterly wind just 3 days out, remain sceptical.

However, my long-range winter forecast expected a cold second half of January and this is the back-up for it.

I'm not yet 100% certain of snowmageddon but it could be a very memorable spell of weather.

Read on...

Wednesday I am hopeful of some spells of sunshine but with a band of cloud close to the south it is only 60% likely. 8'C by day, 2'C by night.
Thursday looks wet all day, but even this close it is not certain, around 7'C.
Friday looks cool and mostly dry, perhaps some light rain in the morning, 5'C by day, 2'C by night.
Saturday is very interesting. Low pressure heading from the west with cold air digging in from the east. Currently money would be on rain turning to snow (40%) with 5-10cm possible but it could just rain (25%), it could just snow 10cm or so (25%) - and it might just be dry and cold (10%). Around 1'C by day and -4'C overnight.

Remember - forecasting snow in Reading is marginal and it is quite possible I will not be able to say with certainty even the day before.

Sunday looks very cold, but currently looks dry with the chance of more snow overnight. -2'C by day, -8'C at night.

So be prepared for significant disruption. But remember it isn't definite yet. I'd say I am 80% confident of a cold spell, 60% confident of some snow, 40% confident of disruptive snow.