Cold on the way out, mild, increasingly wet and windy on the way in

After a very dull first half to February with below average temperatures, a big change is on the way that will bring milder air to all parts later this week, with temperatures potentially reaching the mid-teens. But with the milder air there will be more unsettled and windier conditions, with rain at times, mostly in the north and west, also gales look to develop across the north and west on Friday and more widely over the weekend. 

Watch how winds turn from southeasterly to southwesterly from tomorrow through to Friday, brigning a change in airmasses.

The change is coming about because blocking high pressure close to the east will weaken and retreat considerably during the week, allowing a deep upper low, a segment of the tropospheric polar vortex,  to move east out of northern Canada across the North Atlantic during the week. This will push a strong jet stream across the Atlantic to push in towards the UK during the week, bringing frontal systems in across the west initially, before moving east across the UK later in the week. Isobars will also tighten to the east of a large multi-centred area of low pressure to the west over the Atlantic.

Watch how a strong jet stream pushing across the N Atlantic takes aim at the UK from the middle of this week

With low pressure edging in from the west and high pressure retreating over the near continent, the flow will switch from a chilly southeasterly flow feeding in from a cold central and eastern Europe early this week, to a milder southwesterly from Thursday, which will usher in tropical maritime air from a long way south, so temperatures will respond by rising into the low teens widely on Thursday and Friday, perhaps 15C locally across eastern England and east of high ground on Friday.

For now, it will be mostly dry across the UK during the first half of this week, thankfully with more in the way of sunshine too, compared to last week across central, southern and eastern areas of England, but with clear skies tonight, a risk of frost again. Cloudier and windier further west, with weather fronts moving in across Ireland later today then spreading rain, sleet and snow in across Scotland tonight and through Tuesday morning, before petering out by lunchtime, snow could fall to low levels for a time overnight, but becoming confined to hills through tomorrow morning. Remaining cloudy across Scotland though. Elsewhere on Tuesday, it should turn brighter from the south and stay dry.

Wednesday looking cloudier, with a weakening front moving east, which will bring a band of patchy rain with it, though not much if any reaching eastern England. Temperatures starting to recover as winds turn more southerly.

Turning milder as we head through Thursday and Friday, but also turning increasingly windy, as winds turn southwesterly and strengthen. Gales look to develop across the west on Friday, as a deepening secondary low tracks northeast to the northwest while a cold front sweeps east, both tightening isobars, gusts of 50-60mph across the north and west look likely, perhaps upto 70mph along western coasts and hills. Outbreaks of rain spreading across most areas too on Friday. 

Could turn very windy in the north and west on Friday

The windy and unsettled theme continues through the weekend, with potential for a deepening area of low pressure to zip northeast across the North Atlantic to arrive to the northwest of the British Isles on Sunday, bringing gales and heavy rain, perhaps severe gales across the west. The low starts its life as a winter storm forming over the central & southern Plains of the USA on Tuesday, which will then track to mid-Atlantic states before  crossing the North Atlantic, deepening as it does so in the left exit of a strong jet stream, before arriving to the northwest of the British Isles on Sunday. The track of this low may change, so we are keeping an eye on it, though most models, for now, track the low to the northwest of the UK. But it’s looking stormy for the second half of the weekend. Mild though, with temperatures reaching low double figures.

We may see another deepening low move off the Atlantic but tracking further south across southern areas early next week, but a great deal of uncertainty by then. What the ensembles do show is a trend downwards in temperatures next week, closer to the seasonal average, rather than well above average temperatures that we’ll experience later this week. Could even be a return if wintry precipitation across northern hills.