Met Office issues UK storm alert as study warns of 'severe hailstones' up to 5cm large

The Met Office has issued two yellow weather warnings for Saturday, with heavy rain posing a risk of flooding and disruption. The agency has issued the warning for western Scotland from 8am tomorrow morning, lasting for the entirety of Saturday, whilst a similar warning will be in place in Northern Ireland from 7am until 7pm.

A Met Office forecast for Saturday said: "Rain stays persistent across Scotland which can be heavy at times, and moves eastwards across Wales and England. Sunny spells in the far south east but cloudier elsewhere." The agency warned that flooding of businesses and homes is possible which journeys, especially on public transport, are likely to be impacted. They added: "Outbreaks of rain will arrive across western and southwestern parts of Scotland on Saturday morning, likely becoming persistent and heavy at times, before slowly clearing northeastwards later on Saturday evening.

"30 to 50 mm rain is likely quite widely, with up to 70 mm possible across western parts. This may lead to some flooding and disruption."

They advised "Check if your property could be at risk of flooding. If so, consider preparing a flood plan and an emergency flood kit.

"Give yourself the best chance of avoiding delays by checking road conditions if driving, or bus and train timetables, amending your travel plans if necessary."

The warning comes as the agency released shocking research which shows the changing risks of hailstones as the climate in Europe warms up.

A new study, conducted by experts from the Met Office, Newcastle University and the University of Bristol found that climate change may lead to less frequent but bigger and more devastating hailstorms.

Published in the journal Nature Communications, the study shows that, under a high-emissions scenario (RCP8.5), severe hail is likely to become less common, except potentially for very large hail.

Severe hail has a diameter of 2 cm, while a diameter of 5 cm or more is considered very large. Bigger hailstones cause more damage than smaller ones, and even a small increase in their size could outweigh any benefits from having fewer hailstorms overall.

The researchers attribute this decrease to more than one factor. Hail forms higher in the atmosphere as it warms, where storm updrafts could be weaker, and this gives hail more time to melt before reaching the ground. Another factor is the weakening large scale circulation, affecting the vertical profile of winds and leading to environments not beneficial for thunderstorm organisation.

Study lead author, Dr Abdullah Kahraman said: "Our findings indicate that the effects of climate change on severe thunderstorms are more complex than previously thought, and high-resolution models can produce results that differ significantly from earlier research.

"Society may need to prepare for less frequent, yet more damaging hail events locally, in a 5-degree warmer future. "

Professor Lizzie Kendon added: "These results are very concerning. They imply we need to be prepared for tropical-type hailstorms impacting Europe in the future, associated with very large hailstones that can cause severe impacts.