For nearly as long as the modern computer has existed, it has been used to forecast the weather. First used during World War II to simulate (模拟) nuclear weapons, computers were soon adopted to simulate the future state of the atmosphere, creating the modern discipline of weather prediction. Although that discipline has grown ever more complicated and now produces reliable forecasts several weeks in advance, its approach remains the same: using large amounts of calculating power to solve equations (方程).

Over the past year, artificial intelligence (AI) has begun to change that. Tech companies including Google and Nvidia have trained AI models to predict the weather up to 10 days in advance, with an accuracy equaling or even topping traditional models — and with far less calculation overhead. Rather than solving equations, these AI models predict the near future based on patterns learned through training on 40 years of past weather, which is recorded by the traditional model of the European Centre for Medium-Range Weather Forecasts (ECMWF), the world’s top weather agency. Once trained, the AI models can work out a forecast on a computer in 1 minute rather than taking 2 hours to run on a supercomputer.

ECMWF has already begun to produce its own AI forecast, and other weather agencies are eager to catch up. The new models aren’t perfect. They struggle to predict certain essential features—hurricane intensity, for example. But AI forecasters will only improve as they begin to learn from direct weather observations collected by sensors, not just data already passed through existing models. Besides, their speed could allow agencies to run them over and over, as they capture in the atmosphere the full spread of uncertainty, be it necessary or unnecessary for weather prediction.

No one expects traditional weather prediction to disappear. Another branch, climate models, an extension of weather forecasting, for example, rely on equation solving just as traditional weather models do. But in the long term, the output of climate models may itself become training data for a climate forecasting AI, which might ultimately do a better job than the traditional models.

A storm hit Houston, Texas, on Tuesday. It brought heavy rains and rising floodwaters. By Tuesday night, some parts of the city had received 10 inches of rain. Police and firefighters helped people move to safe places. They also saved people from cars and buses that were stuck on roads.

Certain areas around Houston were hit really hard. In just four hours, more than seven inches of rain fell in Sugar Land in the southwest of Houston. Cars could not pass through any of the area’s main roadways. On Twitter, Sugar Land city officials asked people to get to high ground.

Tuesday’s rain hit parts of Texas that Hurricane Harvey had already damaged almost two years ago. Hurricane Harvey in August, 2017 was the second most costly hurricane in US history. It caused $125 billion worth of damage in Texas. In the Houston area, 36 people died and about 150,000 homes were flooded.

A spokesman for the Harris County Office of Homeland Security and Emergency Management said that this week’s rain “is not in any way a Harvey-level event”.

But the worst may not be over yet. People will have a break from the heavy rain on Wednesday.

According to the National Weather Service, the Texas Gulf Coast will continue to experience heavy rain later in the week.“Today should be our quietest over the next few days for rainfall,”said Don Oettinger, a National Weather Service meteorologist (气象学家).

Houston Fire Chief Samuel Peia warned,“As there is too much water on the ground and flash floods are likely to happen, we hope people are careful of what they’re doing and encourage them to stay home. There’s no sense in putting yourself, firefighters or anybody in danger needlessly.”

Weather Report

(8:00 a. m. December 17-8:00 a. m. December 18)

Influenced by a cold front, northern Xinjiang, the eastern Qinghai-Tibet Plateau(高原)and the northern and eastern parts of Heilongjiang are expected to experience light snow today. Drizzle(小雨) is forecast for most areas of Sichuan and western coastal areas of South China. Northerly winds of force 4-6 are expected to affect western and southwestern Inner Mongolia, and most parts of Northeast China, while northerly winds of force 5-7 will sweep across the Bohai Sea, the northern parts of the Yellow Sea, the East China Sea, the Taiwan Straits, and the central and northern parts of the South China Sea.

Weather forecast for major Chinese cities