Monday 27th September 2021

Autumn has returned and it is an unsettled week or so to come.

Thanks to Tracy for the photograph.

Tonight sees clear skies and will be breezy, down to around 9’C. Cloud thickening by dawn.

Tuesday sees a large low pressure trough from roughly Greenland to the UK, with the main low over Iceland and a secondary low forming over us.

It starts bright with some sunny spells, but cloud will bubble up and heavy showers will spread inland – likely all seeing a few heavy showers, a small chance of thunder. By late afternoon/early evening, a band of heavy/very heavy rain will spread across from the west, lasting around 2 hours, perhaps longer – a bit of uncertainty on how quick it clears. Reaching around 17’C and breezy. Reasonably clear skies overnight, a very small chance of a shower, down to around 8’C.

Wednesday will be fine with good sunny spells, but feeling cooler in a north-westerly breeze at around 15’C. Some cloud around, notably late morning to mid-afternoon, and a small chance of a shower. Clear skies for much of the night, though cloud thickening before dawn, perhaps a light shower by dawn, 8’C.

Thursday sees the next weather front spreading down from the north-west but a weaker affair this one. Bright to start, some hazy sunshine but plenty of cloud and maybe a light shower. Generally fairly cloudy in the afternoon, some bits of rain at times, a little brightness, becoming windy and a bit milder, 16’C or so. Cloudy overnight with occasional bits of rain, mild and windy too, 15’C.

Friday is a tad uncertain on details, but broadly sees heavy showers and/or heavy rain moving east – but timing is uncertain with some sunny spells possible. Windy and around 16’C – showers less likely later in the afternoon. Clear spells overnight, down to around 7’C.

Same kind of pattern into the weekend – the main low pressure system to our north with a developing secondary low probably heading our way – these secondary lows can be quite nasty if you catch them in their peak development phase so there is a small-moderate chance of some very strong winds – but not possible to determine until closer to the time.

The whole development of this probable second low is uncertain (timing, track and whether it even develops at all), so it is possible that it arrives during the day and brings a wet and windy day for Saturday – but more likely it doesn’t and it will be quite reasonable, with decent sunny spells and just a small chance of an afternoon shower. Quite windy, around 15’C.

Assuming this secondary low develops as per more likely outcome, then overnight will see heavy rain and strong winds.

That would leave Sunday windy with sunny spells and scattered showers – likely on the cool side too, say 13’C very approximately.

Again, I stress the uncertainty over details – this possibly nasty low could be Saturday day, is more likely Saturday night, but could even be Sunday instead. It should track over England, but it isn’t impossible that it would be further south over France and we’ll miss the heavy rain/strong winds. There is a small chance of gales or even severe gales.

Next week likely starts windy and showery, perhaps with another area of rain.

Tentative suggestions that high pressure may build from Wednesday to re-assert more dry, sunny weather – we may even see more relative warmth at some point.

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