Yellow warnings remain in force as rain and thunderstorms hit parts of UK

Downpours and thunderstorms will continue to bring the risk of flooding to parts of the UK on Wednesday.

A Met Office yellow warning for thunderstorms is valid until 22:00 BST, and was amended on Wednesday morning to cover northern and eastern Wales, as well as north-west England, the Midlands and parts of eastern and southern England.

The rain could be heavy enough to bring flash flooding and travel disruption, with lightning and large hail posing additional hazards.

Another Met Office yellow warning is in place for Thursday, when more thunderstorms are expected.

For some areas that have seen barely any rain so far this August, the next few days could bring the wettest weather in many weeks.

The Met Office yellow thunderstorm warning covers a large swathe of England and Wales.

After some early cloud and rain, sunny spells will develop across the area.

However, scattered thundery downpours will spring up during the afternoon.

As much as 20-30mm (0.8-1.2in) of rain could fall in some locations within just an hour, and it is even possible that 40-50mm (1.6-2in) could accumulate over a few hours.

However, due to the hit-and-miss nature of showers, some places will miss the rain and weather apps may struggle to get the detail of the forecast correct.

Where the rain does fall, flash flooding is a real concern. This will be especially problematic where the ground is hard after the prolonged dry spell, making it difficult for the water to soak in.

Difficult driving conditions are expected with the chance that some roads could be closed.

Large hail and frequent lightning are also possible.

Northern Ireland will also see some showers but these are likely to be less intense with less thunder.

Many parts of Scotland will remain dry with sunny spells, although some showers are likely in the south-west later.

Thursday will bring another zone of thunderstorms, again affecting mostly England and Wales.

The Met Office has issued a further yellow weather warning, valid from 06:00 until 22:00 BST.

Widespread rainfall totals of 20-30mm (0.8-1.2in) are expected in the warning area within three hours, while some areas could see 50mm (2in) within the same timeframe.

There is a small chance that eastern-facing hills - exposed to easterly winds - could record 75mm (3in) during 12 hours, which would bring a significant flood risk.

Gusty winds may also accompany the storms, especially in southern England on Thursday morning.

The showers may eventually reach southern Scotland and Northern Ireland but are likely to weaken and become less intense as they drift northwards.

Despite a period of unsettled weather last week, some southern parts of the UK have still seen barely any rain recently.

Brize Norton in Oxfordshire has recorded just 0.4mm of rain so far this August, less than 1% of what it would normally expect during the month as a whole.

In July, it received only 1mm.

Kew Gardens recorded no rain at all in July, and only 1.8mm so far this month.

It means the rain we are expecting this week is likely to far outstrip what has fallen recently in some areas.

Thunderstorms are often very hit-and-miss.

Some places can see flooding downpours while others, perhaps only a few miles away, avoid the heaviest rain and stay essentially dry.

Weather apps - including the BBC Weather app - can struggle in these scenarios.

Forecasters know that the conditions are ripe for storms to form, with warm humid air across the UK interacting with a zone of colder air pushing in from the west, higher in the atmosphere.

This generates low pressure and instability.

However, the computer weather models that drive weather apps will always struggle to pinpoint exactly where and when the biggest storms will spring up.

It is a bit like heating popcorn kernels in a pan.

You cannot know precisely which kernels will pop and in which order, while some kernels may not pop at all.

Some of the storms will also occur at night, which may mean they do not show up in the daily weather icons.

It is worth keeping an eye on the hourly weather symbols, as well as the percentage chances of rain, if you are making outdoor plans.