“And lastly, a subject close to all our hearts – the weather…” With these words each morning John Parry, the PA announcer, introduces the day’s forecast in a tone that suggests an affectionate complicity with his public. He knows that we know that when he archly says “we may well have rain later” what he really means is “we will have rain later”. Somehow, the fact he moots it only as a possibility reduces frustration when the first umbrellas open.
The process of predicting when a drop of rain will fall on the courts of the All England Club is now more consistent than a Nadal groundstroke. In an office above the Referee’s Office, official forecaster Chris Tubbs sits next to John Parry at a desk in front of a wide window which provides a perfect cloud-watching vista. Chris is a meteorologist and John a former military parachutist used to dealing with strata of weather. They have a good combined instinct for conditions and a professional sense of excitement about tracking a band of rain. “We often make a mad rush to the roof to see it approaching, to see how dark the cloud is and how fast it’s moving,” says Chris fervently. “When it’s raining, we work closely together to script carefully the information we impart.”
The centre of the Rain Department’s universe is a tiny laptop, linked to the Met Office headquarters in Exeter, which displays a radar map of the south of England with a black dot marking Wimbledon. On this screen Chris monitors a mass of fluorescent blobs (rain cloud formations) as they typically move from the south west towards London. Different colours represent different amounts of rainfall in millimetres per hour. Bizarrely, the darker the blob the less threatening it is. Yellow, however, signifies 3 to 6mm per hour which counts as “good moderate rain”.
Chris concedes his job is not for the faint-hearted. “I am the one who has to tell Andrew Jarrett [Championship Referee] when precipitation is approaching. As it moves closer, I can give him more detailed timings so he can prepare ground staff who might have to bring the covers on or ultimately re-schedule play,” he explains. “Rain gives him a lot to think about, such as TV audiences. And the time of day the rain falls can disturb the order of play.”
An overall forecast is built up by consulting data from European and US Met Centres as well as the Met Office. Both John and Chris have family in Exeter, Cardiff, Harrow and so on, whom they telephone to ask ‘how’s the weather?’ “The radar screen shows us what falls out of the sky but it’s not necessarily what arrives on the ground. Points on the ground are very useful to give us an indication of how heavy an outbreak of rain to expect,” Chris says.
Typically, weather spotted in the south west of England will diminish by the time it blows across to the south east. “A coherent band of rain across Swindon will usually have broken up by the time it gets to us. The nightmare scenario is a weather formation that isn’t easily tracked. Last year there was a very strong jet stream, and heavy thunderstorms travelling very quickly from France, and developing on their way. That was very difficult.”
The forecast for tomorrow (Thursday) is: A rather cloudy morning with some showery rain to start. Becoming brighter with sunny intervals developing but the odd isolated heavy shower may also develop. Very warm and humid. Maximum temperature 27 deg C (81 deg F).
Note that “may also develop”!