Wednesday 12th August 2020 – Thunderstorm Chances

Here we go again. One last day very hot day before temperatures slowly start to become less hot, though humidity may be even higher tomorrow than today.

We were the breeding ground for storms yesterday – some of you will have seen the towers going up, but then not being able to form properly, I assume due to the atmospheric cap, and fading away.

A few scattered thundery downpours did develop across the south – I had some rain and some rumbles of thunder in Harrow in the evening, and far from “clearing the air” (as per the well-intended myth) it was much more humid afterwards! And I suspect what we saw breeding across the south was what brought spectacular thunderstorms in some parts of the north of England and also Scotland last night.

So more hot sunshine today, temperatures should reach 33’C, perhaps 35’C. And it will be humid.

Thunderstorms will break out during the afternoon, perhaps as early as 1pm/2pm but that is uncertain. You’ll likely see them develop in straight lines at first, where winds converge from different directions and force convection upwards – and hence breaking the atmospheric cap.

Exactly where the afternoon storms will break out is uncertain, shock horror, though I think the sweet spot is somewhere between Bristol and Birmingham, with parts of Wales too. We’ll still have a 15% chance here.

In the evening there should be more widespread thunderstorms developing – though still many places missing them, so around a 25% chance in the evening.

And then there is the potential to import some French thunderstorms overnight – but this is also a small and uncertain chance.

Should you get a thunderstorm, large hail, damaging wind gusts, torrential rain with localised flooding and fairly frequent lightning are all possible.

Leave a Reply

Your email address will not be published. Required fields are marked *