BBC monthly outlook
Summary
Cold spell continuing into January. Snow for some.
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Wednesday 30 December – Sunday 3 January
Remaining cold. Snow showers and frost.
A few of us have already seen some snowfall this week. There is more on the way for many during the rest of the week. A combination of a large high pressure ridge over the north Atlantic and low pressure areas over the North Sea is leading to cold northerly winds over the UK. On Wednesday, a small low pressure area will track eastwards across south-west England and the English Channel. This threatens to bring some sleet and snow to some southern counties of the UK on Wednesday afternoon, evening and overnight.
But recent computer model runs have been trending further and further south with its track and making it a weaker feature. So, we may end up with just some localised snowfall over the hills of southern England. Further north, cold and frosty early and late in the day, with a risk of freezing fog patches on Wednesday night. Ice on untreated surfaces. Sleet, hail and snow showers will continue in coastal counties. Throughout the day on Thursday, sleet and snow showers will become more widespread and organised, pushing southwards from Scotland over central parts of the UK.
Further snow accumulations and ice over the higher ground. The end of this week will remain cold with widespread frost at night. The days will be cold too, with winds swinging into the north-east. A sleet or snow shower is possible almost anywhere, but most likely over the northern and eastern half of the UK. Further local snow accumulations.
Monday 4 January – Sunday 10 January
The cold pattern continuing. Risk of snow showers.
Remaining colder than average, as the UK remains on the cold side of high pressure over the far north Atlantic, Iceland and Greenland. Last winter, we failed to see an Arctic high pressure blocking pattern develop like this, and we ended up with mild and very wet, westerly winter. The middle part of this current winter is certainly proving to be different. The succession of Atlantic low pressure areas and fronts that normally bring the UK frequent south-westerly winds, cloud and rain will be diverted to southern Europe, and then down into northern Scandinavia. This means that western areas of the UK, in particular, will see less rainfall than normal, with a reduced threat of gales and flooding.
Indeed, after the very wet mid-December period, the river levels will get a chance to return closer to normal. It will still be cold enough for showers to fall as sleet and snow, leading to additional accumulations in places. Frost, ice and freezing fog are all potential hazards. There is chance that a new blast of cold air from the Arctic will sweep south in the second half of the week. But at the moment it doesn't look anywhere near as intense as the 'Beast from the East' cold spell in early March 2018! That will take some beating.
Monday 11 January – Sunday 24 January
A gradual transition to wetter and not as cold.
The week beginning Monday 11th January is expected to remain colder than average, particularly during the first half of this week and across the northern half of the UK. With persistent high pressure over Greenland and Iceland, this will serve to continue to divert the north Atlantic low pressure track into Spain and France. It will also encourage cold air flows from the Arctic to push into the UK from the north. But compared with the previous week, the low pressure areas out over the north Atlantic will start to become more vigorous and nudge closer to the south-west of the UK.
This could lead to a period of quite severe winter weather for a short time, as approaching fronts and heavy rain move into the colder air over the UK. Strong easterly winds and heavy snow would be likely, especially over central and northern areas where the cold air is most entrenched. It's far too early to be any more specific, but even at these early stages we can see some potential for such impactful UK weather in the large scale northern hemisphere weather patterns. Heading through mid-January and beyond, the low pressure areas and milder air from the south-west seem most likely to win out, with low pressure becoming a significant feature overhead the UK.
Milder air from the south-west will be more common again, especially over southern England and Wales. A return to the pre-Christmas weather pattern is indicated by the latest models, with plenty of wet weather over England and Wales, strong winds in the south at times. River levels should have reduced since the flooding around Christmas, but if rainfall becomes prolonged then we should be mindful of this hazard. Scotland may find it harder to shake off the cold air, with occasional frost and snow most likely here, when low pressure areas clear eastwards from the UK into Scandinavia.
Further ahead
There is plenty of uncertainty on the detail for mid-late January, as the weather influences on the UK pattern start to conflict. Our update will offer the latest thoughts on whether the cold spell could last throughout the month or not.
https://www.bbc.co.uk/weather/outlook