Yellow weather warnings issued as thunderstorms and flooding forecast

Yellow weather warnings issued as thunderstorms and flooding forecast Yellow weather warnings have been issued by the Met Office as forecasters predict heavy rain and thunderstorms across parts of the UK later this week. The warnings, which cover Wednesday and Thursday, apply to areas including east Wales, the Midlands, southern England, East Anglia and London, according to BBC meteorologist Tomasz Schafernaker. He said the event could become one of the most widespread episodes of heavy rain seen over southern and central UK this summer. While the rain will relieve drought‑stricken regions, the Met Office cautions that rapid accumulation on parched, hard ground may trigger flash flooding. Lightning, large hail and gusty winds are also possible. The first wave of storms is expected to move northward from France on Wednesday morning. Initial showers may reach Cornwall and the West Country Tuesday evening, with heavier, thunder‑laden downpours developing later that night. The earliest batch of heavy showers could affect the southeast coast of England around midnight, then sweep across Greater London before advancing into the home counties and East Anglia. The first yellow warning is set to take effect at 03:00 BST on Wednesday and remain in force until 22:00 BST. Although not every location within the warning area will experience thunderstorms, those that do could see 20‑30 mm of rain in less than an hour, with the hardest‑hit spots potentially receiving 40‑50 mm over two to three hours. Flash flooding is a risk where the soil is dry and impermeable, preventing absorption. The most intense downpours may also bring hail and strong winds. During Wednesday morning, the storms may push farther north into the Midlands and the Peak District, though forecast confidence regarding exact placement and intensity diminishes. A second yellow warning for thunderstorms will become active at 06:00 BST on Thursday and continue until 22:00 BST. Some storms may stall over the Midlands, Wales and northern England, increasing the chance of further flash flooding. Many areas could receive 20‑30 mm of rain in just three hours, with isolated spots possibly seeing up to 50 mm. The Met Office notes a small chance of substantially higher totals, especially on east‑facing higher ground, where more than 75 mm could fall within 12 hours. Lightning is expected to be frequent and hail of approximately 1‑2 cm may accompany the storms. Thunderstorms are notoriously difficult to predict because they can develop rapidly over a small area. Minor variations in temperature, humidity, wind and atmospheric instability determine whether a storm forms and where it tracks. Forecast models can indicate the general threat across a broad region, but pinpointing the precise time and place of an individual storm remains challenging. Even a shift of a few kilometres can mean the difference between a torrential downpour with thunder and lightning and completely dry conditions.