Weather roller-coaster in week ahead: some rain, some warm sunshine

The weather is looking to be on a roller coaster ride in the week ahead, some rain can be expected at some point for many early in the week – as low pressure and fronts push in from the southwest, a drier spell mid-week, as a brief ridge of high pressure builds in, then turning unsettled to end the week – as a strong jet stream pushes in from the Atlantic.

The remnants of ex-Hurricane Larry, which is now a deep low headed towards the southern tip of Greenland today, although far away, is having an indirect impact by throwing a lot of energy poleward - causing the jet stream to buckle over the North Atlantic and Europe. This has caused a little uncertainty in the models for the next few days on the progress of weather fronts and low pressure trying to push rain up from the southwest into England and Wales, with the ex-Hurricane building an area of high pressure just to the west of Ireland within the ridge of the jet stream as it buckles. And it’s the position of this high that’s caused a little uncertainty in how far northeast rain gets today and early next week, though it looks like many areas of England and Wales will see some rain between later today and Tuesday afternoon – as low pressure and its associated fronts try to push northeast. Some showers possible for Scotland but for many its looking dry here.

Sunday will be a largely dry and bright day, with variable amounts of cloud and sunshine at times. However, cloud will thicken in the west and outbreaks of rain will push northeast across Wales and northern England into the afternoon and perhaps into parts of SW England and the Midlands this evening. Temperatures generally reaching 15-19C, perhaps 20-21C across SE England and East Anglia.

Outbreaks of rain then look to erratically spread northeast across Wales, Ireland, N. Ireland, northern and western England on Monday. Much of Scotland away from the southwest and eastern England probably staying dry and bright with sunny spells at times, just a small chance of a shower. Temperatures reaching 16-18C in the cloudy and damp west, 18-20C across sunnier parts of Scotland and much of eastern England.

Some uncertainty by Tuesday, but the European models indicate a heavier and perhaps thundery area of rain moving northeast across southern and eastern England on Tuesday morning, while the American GFS model shows this heavy thundery rain staying on the near continent. Otherwise, any morning rain towards eastern England should clear to join the rest of the UK to sunny spells and scattered showers, most of the showers probably in the north and west. A little warmer for more of England and Wales, temperatures reaching the low twenties Celsius. High teens for Scotland and N. Ireland.

Model uncertainty on Tuesday morning as ECMWF vs GFS charts side-by-side for 9am show below:

It looks like drying up by mid-week, as a ridge of high pressure builds in from southwest, with many areas dry with sunny spells on Wednesday and Thursday, though wind and rain may move into the far northwest later on Thursday. Temperatures reaching 20-23C in the south, 16-19C in the north.

All change again as we end the week, with a spell of wet and windy weather sweeping east across the UK as a strong jet stream charges towards the UK from the Atlantic and deep low pressure moves into the northwest. Uncertainty grows by next weekend over whether the strong jet stream and low pressure dominates over the UK, as suggested by the European ECMWF model – continuing unsettled conditions. Or whether high pressure builds in from the southwest across the south keeping unsettled conditions confined to the northwest.