The humidity that has been hovering since the end of June is here for good, at least until the end of July. And this humidity will bring its share of thunderstorms, which are difficult to predict. Better to stay on the lookout for weather alerts, experts say.
“If we look at the statistics, we see that we have never had such a wet first half of July since 1953,” says Patrick Duplessis, meteorologist at MétéoMédia.
The problem is that humidity often rhymes with thunderstorms, as evidenced by the seven thunderstorms that occurred between June 24 and July 21. During the same period last year, the station located at Montreal-Trudeau airport had detected only one.
“To create storm clouds, it takes a lot of humidity,” explains Patrick Duplessis. Moisture is one of the ingredients of a thunderstorm formation. »
Hard, hard to predict thunderstorms
Other factors that go into the formation of thunderstorms include the heat pattern and the winds, both at the surface and aloft. A complex meteorological phenomenon, but above all difficult to predict, according to the meteorologist.
“This is a parameter that is difficult to predict locally in Quebec,” notes Patrick Duplessis. Storms are localized. It never lasts all day. It’s hard to tell exactly when it’s gonna hit and [quelle ville] it’s going to strike, before it forms. »
Still according to the MétéoMédia meteorologist, it is almost impossible to locate a storm 24 hours in advance. And therefore even less a week in advance.
Same story from Peter Kimbell, Environment Canada meteorologist. “We have models that help us predict the weather, but the reliability of the predictions decreases over time. And our models have always had difficulty predicting thunderstorms with good reliability. It continues to be the case. We’re gradually improving, but it’s still a big challenge. »
” We’ll have to to be vigilant ”
In an unstable situation, especially for thunderstorms, it is better to rely on weather warnings issued by the authorities, experts say. “Storms can be very localized,” explains Patrick Duplessis. We must therefore be careful if we do not want to find ourselves in the middle of a flood or on a body of water. There are plenty of ways to get caught in summer thunderstorms. »
Professor of hydroclimatology in the geography department of UQAM, Philippe Gachon is of the same opinion. “We will have to be vigilant. Lake Memphremagog is overflowing, the Richelieu has never been so high in July in 20 years. »
In a context of global warming, the situation should not improve. “We increase the probability of having heavy rain and more violent storms, explains Philippe Gachon. The warmer the atmosphere, the more moisture it can hold. And this humidity can turn into heavy rainfall. »