Monday 3rd May 2021

An unsettled week ahead – quite a mixture of weather with rain, strong winds, colder air, sunshine, showers all in the mix – and perhaps something warmer for the weekend. Though don’t get excited – warmer…but wet.

Thanks to Paul for the photograph – exactly what I required for this forecast.

There is a fair bit of uncertainty for both Thursday and the weekend onwards, so please do bear this in mind.

Monday starts bright but cloud will thicken as a rather deep area of low pressure for early May approaches. Rain from around 2pm onwards, perhaps a shower beforehand, continuing right through the evening, say until 10pm – it will be heavy at times, perhaps occasionally very heavy in the evening. Becoming windy with gusts of 50mph during the evening – enough for the odd tree, fence panel, etc to be blown down. 12’C. Winds remain strong overnight, though not as strong as during the evening hours, rather cloudy with the odd shower too. Down to around 5’C.

Tuesday starts with this low pressure system moving away to our east – pulling in a colder northerly flow.

It will be rather cloudy, the strong winds will remain to make it feel colder than the 12’C we should reach. And there will be plenty of showers, some heavy with a small chance of thunder. Sunshine limited, but there will be some sunny breaks, especially in the afternoon. Showers remain possible in the evening and first part of the night, but it will become mostly dry with variable cloud, down to around 3’C.

Wednesday is another showery day in the fairly cold northerly wind – though the wind will lessen as the day goes on. Some sunny spells but plenty of showers, some heavy or very heavy, thunder and hail both possible. Around 11’C but feeling colder. Skies clearing for a while overnight, though high/mid level cloud increasing later as the next low pressure system approaches. Down to around 2’C.

Thursday is a bit uncertain. Low pressure is set to head roughly in our direction, though there is a chance that it may be a bit further south. The most likely outcome, at around 75% likelihood, is a spell of persistent rain during the morning and early afternoon – brighter with showers to follow, and temperatures somewhere around a rather chilly 8’C. In May. If the low pressure system tracks a bit further south, the 25% chance, then expect something along the lines of limited sunny spells and a few showers, and temperatures around 11’C. Clear skies overnight, down to around 2’C.

Friday looks reasonable in the context of this coming week. Some sunny spells, plenty of fair weather cloud, a couple of showers around so maybe a 50% chance of catching one, and temperatures around 14’C.

Details for the weekend (and indeed Friday night) are uncertain. The general picture is that low pressure will be moving in from the west – spreading some heavy rain across but also dragging some warm air up from the south.

One kind of broad view would be that the low pressure system crosses the UK during the weekend, bringing some heavy rain at some point, also some strong winds – but if the rain times overnight on Friday, then perhaps we squeeze an 18’C and some sunshine on the Saturday, with a chance of showers too – but then cooler for Sunday once the low clears.

Another broad view would be that the low pressure system stalls close to the UK or just to the west – some general rain probable at some point, but also increasing warmth with temperatures around 20’C (give or take), potentially rather humid, with some sunny spells – but also some heavy downpours/thunderstorms breaking out.

It is too early to know how the weekend low pressure system will behave – and whichever evolution it takes will likely determine the weather for the next week or two. The latter, warmer of the two routes gives an easier transition to more general warm weather – though I’d expect some heavy rain/showers at times too. The former outcome would mean more colder, Arctic-sourced air would be more likely to return, though that is likely a drier outcome – and eventually warmer later in the month.

It does feel like quite a pivotal weekend ahead. And a very interesting period of weather model watching this week.

I think it will take another couple of days to resolve this…next full forecast will be on Thursday evening but if I become convinced of the low pressure evolution before then, I will try to update you before then.

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