John Hammond’s Month Ahead – HEATWAVE UPDATE – Could it last all summer?

It’s a divided nation – and I’m not talking about Brexit! For many carefree sun-worshippers, the heatwave can continue all summer long if it likes. For others who struggle with high temperatures, or who are desperate for rain after the driest June on record, it can’t end soon enough. Well as I’ve pointed out before, computer forecast models are often far too hasty in bringing such spells to an end – and they’re at it again. I suggest we prepare for the long haul.

Heatwave continues into early July

Increasing concerns over lack of rain

Gradual trend to cooler, showery weather later

 

MONDAY 2ND JULY – SUNDAY 8TH JULY

Steamy in SW19

The Centre Court roof should be wide open as play commences at Wimbledon on Monday but there may a few nervous glances skyward. The heatwave continues, bar a few thunderstorms. If you’re going – don’t forget to stay hydrated!

Some coastal fringes, especially near the North Sea, may again suffer from chilly mist and low cloud at times. But temperatures for many will be in the mid to high 20s Celsius, and again, some places won’t be far off 30! The air will be more humid than in the week just gone, with cloudier spells that may generate the odd thundery downpour. Initially, these will be focussed across southwestern parts of the UK, but may become more widespread for a time. Alas, I don’t see signs of reliable rain for the gardens, or indeed to dampen those tinder-dry moorlands.

At the Hampton Court Flower Show, the blooms will dazzle in the sunshine; and although you may want to pack a waterproof just in case, there’s a good chance of avoiding the downpours. Similarly, just up the Thames, the English summer scene will look perfect for the Henley Regatta. Thirsty work both aboard and on the river-bank, no doubt!

Earlier indications of more widely cooler weather and rain by the weekend are fading. The jet stream fails again; and as any thundery showers ease away and the clouds part, track temperatures could be sky high for the British Grand Prix at Silverstone.

Hot and dry breeds hot and dry

 

MONDAY 9TH JULY – SUNDAY 15TH JULY

A ‘force-field’ of heat

During prolonged dry spells a peculiar and ominous effect can arise that effectively ‘locks us in’. The dome of hot and dry air which has built up above the increasingly parched ground of northwest Europe is acting as a self-sustaining ‘force-field’, deflecting the jet stream away to the north and so foiling any attempt by rain clouds to make significant inroads. The result is that the ground and the air above it dry out even more which, in turn, further blocks the jet sream’s path. In effect: Hot and dry breeds hot and dry. This effect was seen in some memorable heatwaves in the past, such as 1976 and 2003. Forecasters are very aware that it will require big shifts in the wider atmosphere for the jet stream to bring this spell to an end. This seems increasingly unlikely through the first half of July.

The warm and dry theme continues; and as the heatwave extends, so there will continue to be winner and losers. Apart from a few scattered thunderstorms. there’ll be little useful rain for gardeners or farmers. But on a positive note, outdoor festivals such as BST and Latitude will be hoping the fine and dry weather continues. There’ll be some hot acts on stage, and it’ll be pretty warm in the crowd too. Daytime temperatures will wax and wane, depending on subtleties of wind direction; but the evenings look mild and balmy. Great news for camping out too.

The Sussex Downs should look resplendent at the end of the week as the chequered flag is waved at the Goodwood Festival of Speed, although there’s an ever-present chance of an odd summer downpour. Thunderstorms – too much rain in one place, not enough elsewhere.

…the ‘D’ word rears its head

 

MONDAY 16TH JULY – SUNDAY 29TH JULY

Schools break up – weather breaks down?

Last summer the school holidays acted as a trigger for the fine sunny weather to end and the heavens to open. The good news for children and parents is that there are no obvious signs of such a repeat.

The bad news for others is that I see no quick end to our parched summer weather. Instead, inevitably, the ‘D’ word rears its head. Water restrictions will increase as fears of drought heighten.

On the east coast of Scotland at Carnoustie, the fairways could be lightning fast as The Open golf gets under way. Let’s hope for some testing winds too – that might just suit our British players more than most!

There are no clear indications from long-range computer models which way things will go later in the month. But I continue to feel that the weather will revert back to a more normal summer pattern by the end of July. I suspect that the weather will slowly become more mixed, with some inroads being made by the jet stream to bring cooler and more showery interludes. These look most likely across the more northwestern parts of the UK. Further south and east, the heatwave will be last to loosen its grip. But eventually we’ll see rain, and hopefully not too much. Dare I say that most of us will be happy with that.

The festival season continues. At Camp Bestival in Dorset  and the Green Man Festival deep in the Brecon Beacons, happy campers will be hoping we don’t go straight from drought to deluge! I’m hoping not too – for all our sakes. Nobody likes a soggy tent!

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