How the coronavirus is making your daily weather reports even more unreliable

weather report accuracy
Photo via Bill Hails/Flickr (CC BY ND 2.0)

If you’ve been surprised by an inaccurate weather forecast at any point over the past several months, you’re not alone. The coronavirus pandemic has impacted so many areas of our everyday lives, including weather report accuracy.

The reason for this anomaly is fairly simple. With borders closed and most commercial aircraft grounded, meteorologists in the U.S. lost access to approximately 75% of valuable temperature and wind data that commercial airlines provide to help predict short- and long-term forecasts.

Some regions around the world have lost access to up to 90% of commercial airline data, according to the World Meteorological Organization.

Dr. Ying Chen, a senior research associate at the U.K.-based Lancaster Environment Centre, found that forecasts based on global temperature, wind, and precipitation data between March and May of 2020 were off by up to 35.6 degrees when compared to February 2020. 

This was particularly noticeable in regions with heavy air traffic, such as the U.S., and in remote regions that rely on commercial flights due to a dearth of organic data. Considering a number of U.S. airlines furloughed tens of thousands of workers in late September and considering fewer people will be traveling during the Thanksgiving and Christmas holidays, that problem probably won’t get better anytime soon. Especially since one American Airlines cut 100,000 flights for December.

Western Europe, however, saw the least deviation in weather forecast accuracy because the region employs dense networks using other types of sensors. Sensor networks pull data from other avenues such as satellites, radar, and radiosondes—small instruments that are launched into the upper atmosphere daily and provide data as they descend—to predict weather forecasts.

In the event of prolonged lockdowns, Chen believes the key will be replicating these networks in other regions to prevent further interruptions.

But since fewer than 200 radiosondes are launched each day, data collected by commercial aircraft—which transmits readings as often as every few seconds, depending on altitude—has traditionally been more accurate and abundant.

World Meteorological Organization Director-General Petteri Taalas warned of long-term impacts, as national weather agencies “are facing increasingly severe challenges as a result of the coronavirus pandemic, especially in developing countries.”

“As we approach the Atlantic hurricane season, the COVID-19 pandemic poses an additional challenge and may exacerbate multi-hazard risks at a single country level,” Taalas told the New York Times in May.

Considering the hurricane season in the U.S. has been particularly bad so far this year, the pandemic has only made things worse.

On a local weather service forecasting level, data collected during takeoff and landings can be particularly useful when predicting conditions like fog and thunderstorms, helping forecasters understand the ever-changing vertical structure of the lower atmosphere. 

“If you’re looking for things like the likelihood of thunderstorms, the vertical structure of the atmosphere is important,” said Dr. William R. Moninger, a retired NOAA physicist. “… I expect the decrease in weather data could also make a big impact on things like predicting when fog is going to break.”

Sources: New York Times, Nature

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