If you follow social media or read the tabloids, you won’t have missed the headlines of the past few days that a tropical heat wave is on the way for the UK next week. Is this true and how hot will it get? What are the rumors? Some publications are reporting a high of 40ºC in the UK around July 16th. That’s because one of our supercomputer models on Saturday 2 July – for the first time ever – highlighted a scenario where parts of the UK could reach 41ºC later next week. If this were to happen – not likely – it would be unprecedented. The fact that a computer model has even suggested a temperature of over 40ºC in the UK is a first and a worrying sign that climate change predictions are coming true. UK’s hottest forecast to date – GFS computer model forecast for 16 July from Saturday 2 July 2022 Credit: Data: GFS. Website: www.wetterzentrale.de What is computer modeling? To help predict the weather in advance, meteorologists use mathematical predictions made by supercomputers, called computer modeling. There are many of them around the globe, each using historical data and earth observations to give a possible weather scenario – based on probability. In the UK we have the Met Office supercomputer. This requires about half a million observations per day. Where there is no data, the computer will fill in the blanks. The closer we get to the day (or event) of the forecast, the more accurate the model becomes – because it has more information. Sometimes models differ. Sometimes everyone agrees. Currently, the majority of models are highlighting a “warming trend” starting at the end of this week and continuing into next week. But the 40ºC scenario – thankfully – seems unlikely. Most likely scenario (so far) – GFS computer model forecast for July 16th from Monday July 4th. Credit: Data: GFS. Website: www.wetterzentrale.de What is the reality? Remember that the model forecast was almost two weeks ahead. Today, Monday July 4th, after just 48 hours, the temperature forecast for the 16th has already dropped by over 10 degrees. But a 10 degree plunge could still bring parts of the UK to around 30ºC heat later next week. This is higher than the UK Met Office heatwave threshold and higher than the July average. UK heatwave threshold (3 consecutive days or more) Credit: Met Office So at this stage, we’re looking at things warming up from the end of this week, with heatwave criteria possibly being met later next week. It’s July. Heatwaves are becoming more frequent. 30ºC is not as unusual as it was a decade ago. And as we get closer, day by day, the computer models will adjust their predictions using the latest information. Stay tuned to the forecast, not the gossip!
