The latest weather buzz

Weather updates from site founder Brian Gaze that keep you in the know.

Wintry spell on the way

Posted Sat 12th January 2019 14:40

A change in the weather will develop next week. Colder conditions are expected and the risk of snow increases. However things are not clear cut and the synoptic pattern will probably be quite a messy one.

Colder period on the way

Today's London GEFS 06z plot below suggests that colder than average conditions for much of the next 16 days. Unfortunately once the details start are considered things become a lot more confusing and subject to change. I'll try and summarise the key points as I see them:

1) None of the GEFS runs on the plot show deep cold pooling becoming established over the southern half of the UK. Broadly speaking it is a colder, but similar theme in the north. Therefore a repeat of the deep cold spells we saw in February and March 2018 isn't currently on the menu.

2) Quite a lot of precipitation spikes are appearing and the London snow row reaches 12/23 on this update. 

3) Towards the end of the 16 day period 850hPa temperatures are trending towards the average. This is different from a number of other recent GEFS updates.    

So what does it mean? To me it suggests conditions will be marginal for snow at times in the next couple of weeks. In general terms the risk increases the further north you go. However, there is a chance of a significant snow event/s anywhere in the country. I'd break it down approximately as follows: 

1) Low risk to the south of London 

2) Moderate risk in areas between London and the south Yorkshire with high ground such as the Peak district favoured

3) High risk in areas further north. A very high risk over hills such as the Pennines and over the Scottish mountains significant snow is a given - as much as that is possible in the UK

Continent keeps the coldest weather

The reason I've talked about marginal conditions is because it looks as though the coldest upper level will remain over continental Europe. The GFS forecast chart below shows 850hPa temperatures for Sunday 20th January. The deep cold air shown by blue and purple shading is situated to the north and east of the UK.

Although model runs show the blues spilling over the UK at times, the lack of blocking high pressure to the north and east prevents the really deep stuff from becoming established. So at the moment the computer models show quite a different pattern to the one we saw in February and March last year. If you're a snow fan the scenario I've described could be good news. Deep cold pooling isn't needed for snow and the lack of high pressure blocking means there will be precipitation bearing disturbances pushing in at times.   

Things could change as we head through the next month. Scandinavian high pressure blocks are statistically more likely in February. Therefore if we are going to see a full fat Beast From The East this winter it may not be for a while yet. 

TL;DR

A period of colder of weather is expected to develop next week. The core of the cold probably remains over continental Europe for much of the time. In the UK it could become quite changeable and as disturbances run across the country they bring the risk of rain, sleet and snow. Substantial snowfall is very probable over high ground in the north but in general the risk gradually falls the further south you go.  

Live chart preview