Wobbly Wimbledon Weather

Post by
James Peacock MSC
Wobbly Wimbledon Weather

Wimbledon. It’s one of the world’s most prestigious tennis tournaments, staged in a country with famously changeable weather. No wonder, then, that few years go by without at least one utterance of ‘rain stops play’ or something to that effect.

Sure, centre court now has a retractable roof that keeps rainfall impacts to a minimum, but the other courts remain at the full mercy of the weather.

This year’s tournament has been no exception so far, with some light rain or drizzle featuring during the opening two days.

Question is, will the weather settle down and stay dry for longer at a time?

Opening Week: Service Falling Short

Following Tuesday’s mainly cloudy, at times damp offering, I’m afraid Wednesday looks very similar, although again it should become mainly dry once past about 2 pm. Feeling decidedly fresh as temperatures struggle to get past the mid-teens °C – is this July or April?

Thursday will deliver a welcome respite with dry, mainly sunny conditions throughout. Still rather breezy but feeling warm in the sunshine as temperatures reach 21-22 °C.

Alas, this isn’t expected to last. With a bit of luck, Friday might stay dry and somewhat warm until mid-afternoon, but it’ll be increasingly windy, becoming unseasonably so with gusts into the 30s mph by noon. That might lead to some interesting tennis ball flight paths! A wet, perhaps drenching late afternoon and evening is likely to follow; expect little to no play away from centre court.

The weekend’s weather can be summed up as “sunshine and showers”. Initially windy but becoming less so by Sunday. Result being that it’ll feel ever warmer in the sunshine, but the showers that do come along will tend to last longer.

Week Two: Temperatures Rally but Rain may Return Often

For the 2nd week, there’s a robust signal in the forecast model guidance for temperatures to become warmer by Wednesday 10th and then remain that way.

Each coloured line represents an individual run of the 51 that makes up the ECMWF ensemble, while the bold white line indicates the mean of those runs.

However, this isn’t accompanied by any clear indication abundantly dry weather. Broadly, low pressure is predicted to be somewhere close to or over western or north-western UK until at least Friday 12th. With that comes the threat of showers or longer spells of rain interrupting play.

Same line logic as with the previous graph.

What’s more, with warmer air on the scene, its moisture content will be higher, meaning whatever rain does fall can be heavier.

The forecast models are in strong agreement on this overall theme of warmer but rain-prone weather, but disagree on the finer detail, as can be expected when looking a week or more ahead. You can see that in the lack of clustering to the rainfall ‘spikes’ in the above graph; the timing is up in the air.

There’s just a hint that some drier weather might establish by the weekend. My advice, stay tuned to forecasts and apply the adage: Hope for the best, expect the worst!

Post-Wimbledon: Will ‘High Summer’ Break Through?

If you prefer the summer weather to be of a warmer, drier, and sunnier sort, there is reason to be hopeful. Shown below is the latest prediction from the European Centre for Medium range Weather Forecasts (ECMWF)’s ‘extended’ forecast model, which predicts out to 42 days ahead.

Predicted 500 hPa geopotential height anomalies for 3rd week of July 2024 by ECMWF's extended range model. Generally, higher 500 hPa heights correspond to more frequent high pressure in the affected areas.

In this graphic, the orange shading represents an area with an increased chance of high pressure systems dictating the weather – those being what typically bring dry, sunny, warm or hot weather when located either overhead or a little to the south or southeast.

So, what we have here is a signal for high pressure somewhere across the northern half of Europe in the 3rd week of July. It’s not a very strong signal and there’s a lot of wiggle room regarding exactly where a high locates, but it’s better than nothing!

The model gives little indication for the 4th week, beyond a suggestion that the high somewhere over northern Europe might hold on for at least a few days more.

As with the previous chart, but for 4th week of July 2024.

This has much in common with MetSwift’s model prediction produced back in mid-June for the 2nd half of July. The main difference being more of a focus over Scandinavia for the high pressure, meaning there could still be occasional rainfall for the UK & Ireland, especially in the northwest.

Mean sea-level pressure anomalies for 15th-31st July predicted by MetSwift's model, initialised mid-June 2024. Above normal (yellow to red shading) implies stronger or more frequent areas of high pressure than usual, and below normal (blue to purple shading) stronger or more frequent areas of low pressure than usual.

My overall take from this is that we’ll be unlucky to go through the whole of July without at least one spell of 3-5 dry, warm or hot days, but prolonged weather of that nature - i.e. something like we saw in 2018 for example - is unlikely.

James Peacock MSc

Head Meteorologist at MetSwift

Featured photo by Carlo Bazzo on Unsplash