Monday 19th December 2022

Autumn is back. But for how long?

Warning – this forecast gets uncertain very quickly!

Thanks to Nicola for the photograph. Albeit from a couple of months ago – I don’t have any recent rain photographs!

Tonight sees showery rain, some light, some heavy and it will stay mild and windy. 12’C.

Low pressure remains in charge for Tuesday, as it will all week with the jetstream having moved somewhat north – albeit it is rather weak.

Tuesday starts cloudy, there may be a little light rain still to clear too. This will push east to leave a mostly sunny day, just a bit of cloud around. 10’C. Clear skies at first and chilly, down to around 3’C though the odd patch of frost. Clouding over from the west later in the night, with some scattered bits of showery rain possible before dawn.

Wednesday morning sees a band of showery rain crossing first thing, say 3 hours of rain. Sunny spells follow. Cooler, 8’C. Cloud thickening again overnight with some showery rain – down to around 4’C at first but picking up a bit after.

That is already as far as I can go in terms of details.

Thursday and Friday will see low pressure moving across and there will be spells of rain – sometimes heavy. But when it rains, is currently uncertain. It will be mild, say 10’C to 13’C, and windy at times.

Then for the weekend there is going to be a battle between colder air trying to push down from the north, and milder air continuing to try to push up from the south-west.

More likely, at least for us in the south, the milder air wins, but we are talking a 75/25 chance. Where the mild meets the cold, there will be snow on the boundary – which most likely is Scotland or north England, but not impossible down here. So a White Christmas is unlikely, but possible – maybe a 5-10% chance down here.

I think it will be another two days until we have a better handle on the Christmas weekend weather – there is a lot going on in the hemispheric pattern, and it remains unusual – as it has done for 6 weeks or so. Hence our significant cold spell prior.

Even if mild wins out for Christmas (it may even win out in Scotland!), after Christmas and towards New Year is more likely to see a return to cold weather, with the usual wintry risks. Uncertain, but the somewhat more likely outcome.

Appreciate this is all pretty vague, but it is what it is. We need to wait for weather models to determine outcomes for this unusual set-up.

Next update I will try to do before Thursday evening.

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