From Arctic to Atlantic: Biting overnight cold to come but milder air next week

Wednesday was quite a wintry day across parts of the UK. Snow showers continued across northern Scotland, bringing further accumulations, and wintry showers affected the north of N. Ireland. At the other end of the UK, a low pressure system sliding east just to the south of the UK into northern France brought a mixture of rain, sleet and snow on its northern flank across southern England. An amber warning was issued across parts of Devon and Somerset for heavy snow causing disruption over higher routes. The snowfall was quite hit-and-miss, very dependent on how heavy precipitation was.  For example, Brighton and Hove saw several centimeters of snow accumulate in the higher outskirts to the north, bringing difficult driving conditions on the A27 bypass. Snow even fell on the coast at Brighton and Newhaven to the east, but Eastbourne further east it fell as rain the whole time. Likewise much of London saw rain, while further south and southwest snow fell and accumulated, but generally not large amounts. 

Looking at visible satellite imagery, large parts of the Highlands, Southern Uplands of Scotland, the Pennines, Cumbrian Fells, North York Moors and Welsh Mountains are covered in snow this morning, deep in places in the north. Elsewhere across England snow cover is small and rather patchy, can make out snow over the Moors of SW England, Mendips, Salisbury Plain and a few patches over the North and South Downs further east.

Images courtesy of NASA Worldview

As high pressure builds across the UK, it will turn very cold during the next few nights under clear skies, especially where there’s snow cover. After the sun goes down, the heat absorbed by the snow cover is radiated back into the atmosphere, allowing temperatures to fall more than if there was no snow on the ground. So snow covered areas of Scotland and Northern England, in particular, could see some very low night time temperatures tonight and Friday night.Temperatures here could fall as low as -16C, making it the coldest night of the winter so far. Elsewhere, a widespread hard overnight frost is likely, with temperatures falling well below freezing. With snow or water around after recent snow and rainfall, there is a risk of ice on untreated surfaces. 

Temperatures at 6am Saturday morning

There is the chance of some patchy rain, sleet and snow moving in from the west across SW England and south Wales during Friday morning, before fizzling out in the afternoon. Most of any snow falling over higher ground and not likely to amount to much. But this precipitation may add to the risk of ice after dark as skies clear and temperatures fall below freezing.

Fog risk 6am Saturday morning

There is also a risk of freezing fog forming over the next few nights - particularly Friday night across southeast, central and eastern England and Saturday night across eastern England, as temperatures fall well-below freezing. Though patches are likely elsewhere too. Could lead to some nice hoar frosts but also could cause some tricky driving conditions with reduced visibility, while delays are possible at airports.

Severe frost and fog to end the week We have more sharp frosts this week before a milder turn for next week. Many places will remain dry and cold on Saturday but milder, breezy and the chance of rain in the west to end the weekend. Netweather

As we go through Sunday, milder air looks to start to make inroads across western and northern parts, as winds turn south to southwesterly, as high pressure over the UK sinks south. Temperatures returning to around average (high single digits) here then rising into double digits from Monday - which is above average. However, SE England, Midlands and East Anglia are likely to remain chilly until the middle of next week, thanks to lighter winds under high pressure here. Though it may become cloudier, preventing a frost.

Turning milder from the northwest late weekend and through early next week.

From today it looks to become increasingly dry through to the end of next week at least, with high pressure settling close to the south centred over the near continent next week, keeping anticyclonic conditions. The exception will be northern and western Scotland, along with N. Ireland - where a strong southwesterly flow along with Atlantic fronts will bring more in the way of cloud and some patchy rain or drizzle at times. Turning milder across all parts by the middle of next week, mildest across the far west - where temperatures are forecast to reach double digits. 

Dry for the next 7 days

No sign of cold and wintry weather returning any time soon after it turns milder early next week. It looks like the North Atlantic Oscillation is turning positive as we head towards and into the 2nd half of January, which means lower pressure over Iceland and high pressure over western Europe - which allows a mild flow from the southwest across NW Europe including the UK and Ireland.