Thursday 22nd July 2021

I hope you enjoyed summer.

Low pressure will move up from the south-west for this weekend, bringing some downpours and possible thunder/lightning – then the jetstream sinks south next week bringing more changeable conditions – but still some pleasant, warm sunshine too.

Thanks to Chris for the photograph…had to go back a little to find something more appropriate!

Tonight will be another warm night though a little less so than of late, eventually down to around 16’C.

Friday will see more sunny spells, though hazy at times, especially in the afternoon – also some fair weather cloud bubbling up like recent days. Less hot, around 26’C and a bit more humid, but nothing excessive.

Overnight sees the start of the (possibly thundery) breakdown, as showers move up from the south. These kind of breakdowns are always difficult to get the details right – feasibly showers could be as early as midnight, but more likely say 4am onwards. Showers could be very heavy, thunder/lightning is possible though not an especially high chances, say around 25% chance. Also feasible that the showers don’t arrive until dawn.

So for Saturday, our developing low pressure is sat over the south of England.

Therefore we will see heavy showers throughout the day. Suggestions are that they are more likely early-mid morning, and again from mid-afternoon through to the evening (so lunchtime less likely) – but don’t take that as a guarantee as they could occur any time. Possibly very heavy, thunder/lightning could easily be in the mix too – showers could merge into longer spells of heavy rain. Still very warm, humid too, with a bit of sunshine in between showers then around 24’C should be reached. Showers remain possible overnight, down to around 16’C.

Low pressure is still in charge for Sunday. Lots of heavy showers, some very heavy/torrential downpours, hail and thunder/lightning all very possible, arguably even probable. Limited sunshine in between showers. Still warm and humid, around 22’C. Showers fading with clear spells overnight, down to around 14’C.

Monday is an improvement. Low pressure will still be close enough to the east to give a chance of heavy showers, say around a 60% chance so some places will stay dry. Sunny spells and fair weather cloud otherwise, and very warm, around 25’C. Clear spells overnight, down to around 14’C.

Tuesday again looks reasonable. Sunny spells and variable amounts of cloud, still the chance of a heavy shower, say around a 40% chance. Warm, 23’C. Clear spells overnight, down to around 14’C.

Details are uncertain for Wednesday/Thursday, but the general theme is that our weekend low pressure system will be circulating around the UK somewhere as an enlarged trough, with other low pressure systems being attracted to it’s circulation.

This will mean temperatures down to around 20’C or so – lower than average for the time of year, and with some showers or general rain at times, for both Wednesday/Thursday – though some dry spells too with fairly limited sunshine, but some.

Friday and into next weekend will depend on how the low pressure trough develops during the week, and where it situates itself. More likely it will be either over the UK or to our east, meaning temperatures below normal (though still warm given that it is late July) with further showers/rain at times.

There is a small chance instead, that it ends up to our west, and we drag some very warm/hot and humid air up from the south, but I rate it as a 10% chance. Still, 10% chances do happen occasionally.

The more likely outcome for next week is that the low pressure trough reloads from the west/north-west with further showery conditions to come, below average temperatures but also some sunny spells at times.

More likely we will have to wait until around 7th to 10th (ish) for the next build of high pressure and some general settled conditions with some warm sunshine. Earlier cannot be ruled out. Likewise, neither could a continuation of the changeable conditions further into August.

Of course, August brings the wild card of Atlantic hurricanes into the question, which can help over-ride the other factors that are causing my expectations of how early-mid August will play out.

Enjoy your weekend…I’m looking forward to getting back out and about once more after a weekend at home (yeah…I was pinged).

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