Thursday 1st September 2022

Autumn has arrived, and right on cue, so does the rain. Well, heavy showers – but also it will be very warm too.

Thanks to “Facebook User” for the photograph. For some reason I don’t have any rain photographs that I can use…so this is the closest I have.

This evening sees heavy showers spreading up from the south – some heavy, a very small chance of a thunder. Fewer showers around by dawn, and unlikely to be heavy. A fairly warm night, 17’C.

Friday sees low pressure heading down from Iceland as the jetstream is forced south – and this merges with a slack area of low pressure that pushed up from France (slightly earlier than I previously forecasted).

The morning will be mostly dry with some hazy sunshine. A few scattered heavy showers in the afternoon, say a 25% chance of catching one, but otherwise some decent sunny spells and some cloud. Very warm, 25’C, maybe 26’C. Clear spells overnight, down to around 15’C – maybe one or two mist/fog patches by dawn in more sheltered spots.

Saturday starts with hazy sunshine. A few scattered heavy showers developing from around late morning, around a 35% chance of catching one or two, but these push north fairly swiftly, to leave a mostly dry afternoon with hazy sunshine. Very warm, 24’C, maybe 25’C. Fairly cloudy overnight, mostly dry though a light shower possible – down to around 15’C.

By Sunday our low pressure system is well-defined and to the west of the UK, where it stays for a few days, as it is completely cut off from the jetstream and has nowhere to go. Also by this point, there is a tropical storm further west in the Atlantic, wandering around aimlessly. Quite an interesting set-up.

Sunday sees a band of heavy showers erratically pushing east and veering north. Some spots probably staying dry, others getting some general rain, others getting some heavy showers – it looks like quite a mish-mash of outcomes. Otherwise rather cloudy, warm with a little hazy sunshine at times. Temperatures somewhere between 22’C and 24’C. Heavy/very heavy showers probable overnight, though some places may miss them – a fairly warm night at around 17’C.

Confidence on details a bit lower for Monday, so don’t be surprised if wetter or warmer or sunnier than forecast, but broadly I think more in the way of hazy sunshine, and fewer showers – say a 40% chance of one or two heavy showers. Around 24’C, give or take. A stronger signal for very/very heavy showers in the evening and/or overnight, but still uncertain at this stage.

Further heavy showers likely for every day from Tuesday to Friday, as the low pressure very slowly edges east and takes residence over the UK.

No point in attempting details on any particular day at this stage, but showers could be frequent, very heavy and/or thundery – a spell of general heavy rain possible at some point too. Around 22’C to 24’C – still some sunny spells at times. A small chance of overnight mist/fog.

Tentative suggestions of drier conditions next weekend with low pressure fading away and pushing away to our east. Saturday still a chance of showers, Sunday more confidence on some autumnal sunshine. Still likely on the warm side.

However – with two or three tropical storms/hurricanes expected further west in the Atlantic, there is higher uncertainty than usual for next weekend and onwards, though my working theory right now is that they’ll help to promote high pressure over the UK.

My autumn forecast will be issued either this Friday or Saturday, depending on my motivation levels after work tomorrow!

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