More rain on the way but then a shift to colder weather in a weeks time

The UK will remain largely unsettled and wet at times over the next 7 days, with a significant shift toward colder conditions and potential snow from the middle of next week in the north and perhaps all parts by Valentines Day.

Low pressure will remain in charge close to the southwest or west today and over the weekend, bringing further spells of rain or showers.

Friday will be mostly cloudy and windy with spells of rain or showers moving north across many areas, with yellow warnings for rain in the south and snow on northern hills.

Saturday will again be largely cloudy with showers, drizzle or longer spells of rain, heaviest of which are expected in Wales, Northern Ireland, and southwest England. Sunday looks like a greater chance of sunny spells, but there will also be some showers around and remaining breezy.

The start of next week looks to see a drier and brighter respite for a change, which will be welcome news for many areas after relentless rain over recent days, though there could still be a few well-scattered mostly light showers around. However, it won’t last until mid-week for England and Wales, as a band of heavy rain looks to move in from the southwest Tuesday afternoon and evening.

Continuing unsettled next week after a drier start on Monday, rain turning increasingly to snow in the north, as cold air spreads in from the east

However, we will start to see a change from the middle of next week, as cold air returns from the east from a very cold Norway across the north initially, before increasingly cold air spreads southwest across all areas by the end of next week or the following weekend, bringing an increasing risk of snow by next weekend for some.

After a mild start to the week, turning increasingly cold from the northeast by Friday according to 00z EPS mean

There is a lot of uncertainty this far out on how quickly the cold air will spread southwest across the UK later next week and this is down to the track of a ‘trigger’  low moving in off the Atlantic later next week and how quickly it clears east to allow cold air to sweep southwest across the UK in its wake. 00z ECMWF and GFS models differ in respect of this low’s track and quickly they clear it east. 

Differences between ECMWF and GFS with position of low pressure later next week making a difference to how quickly cold air spreads southwest

ECMWF has the low tracking east-southeast across Ireland and southern UK on Thursday, clearing early Friday into the near continent - to allow cold air in from the northeast in its wake, with a much colder and mostly dry weekend to follow, though with wintry showers near coasts.

GFS, however, is more complicated and slower with getting the colder air in. It brings a maturing and filling large low pressure system much further north later next week in across the north, a strong cold easterly flow across northern Scotland bringing plenty of snow on the northern flank of the low, wet at times and less cold further south. A deepening secondary low runs northeast across the far north of France Friday night into Saturday, becoming the main low and its not until this clears northeast from the North Sea that the cold air moves in from the northeast, so delaying arrival of the cold air over the weekend.

00z ECWMF ensembles majority suggest cold air reaching the south by late Friday

00z GFS operational run was at the milder end of its ensemble spread for late next week, suggesting colder air may move in earlier. And a look at the ECMWF ensembles shows fairly tight clustering in favour of turning colder next Friday, with the cold lasting through the weekend of Valentines Day. Though beyond Sunday 15th, the spread widens on how long the cold, cold enough for snow almost anywhere, lasts. This depends on how quickly and the track of further lows moving in off the Atlantic and whether high pressure building in next weekend lingers.