Issued on January 13th 2019. Yes, so far winter has been mild across the United Kingdom with winds generally in from a westerly direction. However there’s an increased consensus within the numerical computer models for colder weather for the final half of January. This isn’t to say that the UK will be plastered with cold and snow for final ten days of the month, it’s just to say that the chance of it turning properly cold (like, it will feel like Winter finally), is growing. One might say that the upcoming cold has been assisted by the recent Stratospheric “split”, during which the tight polar vortex which is like a reinforcement to cold over the Arctic breaks up into little pieces, making it easier for those cold temps to drain out via those little “pieces”…
Turning colder this week:
The first signs of a change are evident this week with temperatures falling in the north tomorrow before the cold air eventually seeps further south on Wednesday. There will be some wintry showers tomorrow, significant snowfall for parts of Northern Scotland with 5-10cm expected by Thursday on high ground via showers, with some light wintry showers draped around northern coasts, perhaps some flurries for the Pennines and Snowdonia to. To start Thursday most in land areas will be dry with a patchy frost, but early on there will still be some wintry showers of rain, sleet and light snow draped around some coastal areas.
Pink = Snow, blue = Rain. Notice the deep blue colors over northern Scotland;
Dry and cold for Thursday:
Thursday will be a colder than average day, the first of possibly quite a few, with highs of 3/4C for the Midlands, 6C on the South Coast and 1-3C for Scotland. Early Friday looks like a cold one, many central and eastern areas seeing a moderate frost with high humidity levels, temperatures down to -4C locally.
Wintry on Friday;
Although there is significant uncertainty, as a weather front progresses into the cold air on Friday there’s the potential for some snowfall. Exactly where and how much, and the exact timing remains uncertain and will be resolved by Thursday. However given that this event is now 3 or so days away there is increasing confidence that some areas will be affected by snow. The most likely areas are parts of Northern England, Wales and the North Midlands, that’s not to say snow is forecast in these areas but the highest chances are these areas. Keep an eye on the forecast. There’s the prospect of something a little milder for the south west simultaneously, with temperatures rising to 6 to 8C in the south west perhaps.
The weekend’s forecast depends on how Friday’s slider low materializes, so confidence is low. However we keep that risk of some snow for northern hills and keep it chilly. Where skies clear early on Saturday a frost is possible and more especially on Sunday morning, gloomy for eastern coasts and in general perhaps quite a cloudy weekend; with the chance of some light rain / hill snow into Scotland later on…
The week of 21st to 25th of January 2019:
This looks like another chilly week. Temperatures are likely to be held below average thanks to a “blocked” pattern – meaning that the usual west to east flow across the North Atlantic is blocked and instead cold air is allowed to drain down from the Arctic. Uncertain as regards to how cold, there’s a low (20%) chance of very cold weather and easterly winds, with a 50% chance of generally cool-cold weather, and a 30% chance of average or milder than average temperatures; so the week look set up for cold as it stands.
And yes, with colder than average temperatures in January comes with it the risk of snowfall, especially to higher ground. I would normally disregard charts 7 days away as being highly uncertain but given recent Stratospheric happenings; charts like these becoming a reality (this one is very cold and quite snowy), this could (could), become a reality;