A fallen tree blocks the movement of commuters on the Bulandshahr-Syana-Garhmukteshwar state highway after a strong storm and heavy rain on Thursday, May 14, 2026. (PTI Photo)More than 100 people died due to powerful thunderstorms that hit Uttar Pradesh earlier this week. The atmospheric phenomenon, called Andhi in meteorological literature, is a common annual phenomenon in the region, but the devastation this year is more widespread. The worst-hit district was Prayagraj, which reported 21 deaths, followed by Mirzapur (19) and Bhadohi (16).During the pre-monsoon season (April and May), sometimes extending into July, many parts of northern India witness these dust storms, accompanied by thunder, lightning, rain, and, at times, hail. Such events occur globally, too, particularly in arid regions.Most such thunderstorms are uneventful. They involve gusty winds of speeds up to 40 and 60 kmph, but more powerful ones can cause widespread destruction. Wind speeds of over 90 kmph can uproot big trees. Walls can collapse, electricity poles and billboards can be toppled, and loose objects can become airborne and turn into dangerous projectiles. Some deaths are reported due to lightning, as well. Commuters make their way through a dust storm, in Prayagraj, Uttar Pradesh, Wednesday, May 13, 2026. (PTI Photo)Stronger eventThe latest thunderstorms were stronger than usual and more widespread. At least eight districts recorded wind speeds over 100 kmph, even hitting 130 kmph in some places, according to the Indian Meteorological Department (IMD).Pre-monsoon thunderstorms in northern India are usually preceded by intense surface heating. Moisture-laden winds, usually from the Bay of Bengal side, provide the necessary fuel.Also Read | Why storms battered Delhi-NCR and turned deadly in UPBut it was the coincidence of a few other meteorological conditions that led to the powerful thunderstorm activity. Temperatures crossed 45°C in many regions, while strong southeasterly winds ensured that moisture from the Bay of Bengal reached even northwestern Uttar Pradesh. As a result, the air near the surface was warm and moist.Story continues below this adDue to the prevailing western disturbances, which are east-moving rain-bearing wind systems that originate beyond Iran and bring rains to India, the air at the top was cool and dry in comparison to the warm air closer to the surface. “This creates instability in the atmosphere, and is a classic triggering mechanism for strong thunderstorms,” IMD director general Mrutyunjay Mohapatra said.The situation was similar to that in 2018, the last time such a thunderstorm event struck UP, with over 100 deaths reported. Several major thunderstorm events occurred in May and June that year. Around a dozen deaths are reported every year due to thunderstorm events of varying intensity in north India, but these are generally distributed over time.Forecast accuracyWeather agencies can predict thunderstorms well in advance. IMD weather bulletins routinely have forecasts for such events, as they did this time. But, as Mohapatra himself acknowledged, the peak wind speeds were under-estimated.Explained | From Western Disturbance to El Niño: The climate terms you’re hearing this summerIMD’s initial forecast predicted speeds up to 60 kmph, later revised to 70 kmph. In its Nowcasts, which describe real-time weather and forecast for the near future, it said wind speeds could reach up to 80-90 kmph.Story continues below this adWhile that covered most thunderstorms, wind speeds exceeded the prediction in some places. “In six-seven districts, wind speeds in excess of 100 kmph were recorded, and our forecasts had not captured that. But overall, the forecast was timely and good. We now have a very strong observation network in Uttar Pradesh, about 2,400 stations, that allows us to predict these kinds of activities more accurately. And we are continuously working to improve our capabilities,” Mohapatra said.Unlike cyclones, evacuation is not an option here after forecasts. The direction of threat from a cyclone is specific — from the sea towards the coastline — and moving people away from the coastline minimises casualties. On the other hand, thunderstorms are a much more dispersed phenomenon, with multiple events happening near each other.