In the lexicon of space talk, the words “Houston, we have a problem” are right up there with that phrase about small steps and giant leaps that Neil Armstrong uttered 50 years ago. On Thursday, the Space City was at the heart of a weather problem as wave after wave of violent thunderstorms, known as Tropical Depression Imelda, swept over the area. They forced the cancellation of flights at George Bush Intercontinental Airport, one of the busiest in the US, and left a trail of devastation across the city. Officials rated the storm as one of the most powerful in recent years. <br/> Forecasters predicted up to 90 centimetres of rain would fall in parts of eastern Texas as the depression moved slowly over the state. Imelda is the first named storm to hit the Houston area since Hurricane Harvey dumped nearly 130 centimetres of rain on parts of the flood-prone city in August 2017, AP reported. Hurricane Harvey flooded more than 150,000 homes and caused an estimated $125 billion in damage in Texas. It is too soon to count the cost of Imelda. The airport was under siege from the weather, with the terminal halls ringing out to the sounds of travellers’ mobile phones emitting emergency alerts warning of flash floods, thunder and lightning. Airline staff did their best to reschedule travellers who missed flights and connections during the hours in which the airport stood still. Those planes that did make it into Houston before the worst of the weather hit were forced to wait in run-off areas beside the runways as gates were shut and ground crew had been advised to stay inside until the worst of the weather passed. One aircraft waited for several hours before being able to taxi the short distance to a gate. The successive waves of lightning and thunder eventually passed, only to be replaced by incessant rain. More than 1,000 rescues and evacuations had been undertaken because of rising water and floods, AP reported. Emergency calls were logged throughout the day. Residents took to social media posting videos of flooding under the trending hashtag of #houstonweather. Some pinned the blame for the floods on climate change, while others questioned why schools were open on a day of such torrential flooding, and others reported being trapped at work as floodwaters rose.