🌪️ Extreme weather

A hurricane begins as a cluster of ordinary thunderstorms over warm ocean water, and if conditions stay favourable, warm enough water, moist air, and light winds that do not disrupt the storm's structure, that cluster can slowly organise itself into a spinning system. As it strengthens, the storm develops a clear centre, the eye, surrounded by a ring of the most intense wind and rain, called the eyewall, and the whole system keeps growing stronger as long as it stays over warm water feeding it energy. Scientists track dozens of factors, sea temperature, wind patterns, and air moisture, to predict whether a developing storm will actually strengthen into a full hurricane or fizzle out.

Tornadoes usually form inside a specific, especially dangerous kind of thunderstorm called a supercell, where winds blowing at different speeds and directions at different heights create a horizontal spinning column of air, which a powerful updraft can then tip upright and stretch down toward the ground. Not every supercell produces a tornado, and scientists still cannot fully explain exactly why some storms spin one up while very similar-looking storms right nearby do not. This unpredictability is exactly why tornado warnings often come with only minutes of notice, compared to the days of advance warning possible for a hurricane.

Meteorologists classify a storm as severe based on specific, measurable thresholds, like hail reaching a certain size, wind gusts above a certain speed, or the storm producing a tornado, rather than just how the storm looks or feels. A storm's severity often comes down to how much energy and instability is available in the atmosphere, warm, moist air near the ground combined with cold, dry air higher up creates far more powerful updrafts than calmer, more uniform air. The exact same storm can be classified completely differently depending on which specific thresholds it crosses, which is why weather warnings use such precise, official language.

Scientists track storms using a combination of tools working together, weather radar that bounces radio waves off raindrops and hail to map exactly where precipitation is falling, satellites watching from space, and sometimes specially equipped aircraft that fly directly into storms to measure conditions firsthand. Doppler radar, a special kind of radar, can even detect the speed and direction air is moving inside a storm, which is exactly how meteorologists spot the rotation that might signal a forming tornado. Combining all these different data sources gives scientists a much fuller picture than any single tool could provide on its own.