Before our westerly air returns let’s celebrate:
Wednesday 19 June could be a minor record breaker for Reigate, as we recorded an (unofficial) maximum temperature of 26.8ºC, one of the warmest temps in the UK! At 22:24 hrs it was still over 20ºC in Reigate… sticky.
This week we have stayed remarkably thunderstorm free despite high temps and humidity: the pressure has been rather high and storms have fed across the Channel further east up the North Sea and brushing Kent, missing Surrey entirely. Thursday may see our first thundery showers of this warm weather episode. Pressure is due to fall as a trough passes to the North of the UK and fronts pass over the UK from N France. Whilst the warmest Euro air will move away to the NE the transition will cause instability and possible thundery heavy showers.
Mind you, the precipitation forecasts from every provider have been wildly inaccurate this week, but this looks more certain than previous episodes. Finally, our mini-heat spike will fade away, quite slowly, over Friday and the weekend looks like a return to a wetter cooler westerly airflow, more like “normal”.
One big benefit of the recent heat wave is spotting unusual Kelvin-Helmholtz wave cloud formations over Reigate (see photo above). As the warm plume arrived from the continent it allowed layers of cirrostratus to condense in a more stable and cooler airstream below. The fast moving warm plume churned the cloud into waves … like ocean breakers. These are not the best examples but they looked pretty amazing and showed off the inversion cap preventing thunderstorms and convection on that occasion.