Exclusive: Rain Forecast Accuracy Hits 10-Year Low Amid Frequent Errors

[Anchor]

Many of you probably felt that this summer's rain forecasts were constantly wrong. We obtained internal data from the Korea Meteorological Administration and confirmed that the precipitation hit rate, which evaluates forecast accuracy, was the lowest this year among the past 10 years.

Reporter Jeong Gu-hui has the details.

[Reporter]

On July 23, citizens held umbrellas in hand following a forecast that it would rain in Seoul, but the timing of the rainfall missed the mark.

[Noh Ji-su (July 23): It keeps changing every hour, so I don't really trust tomorrow's forecast anymore; I just check the weather right on the spot.]

The next day, on July 24, rain was also forecast continuously from early morning until 5:00 PM, but not a single drop of rain fell across all of Seoul.

According to internal Korea Meteorological Administration data obtained by SBS, the weather agency's forecast accuracy for this summer from June to August stood at 84%.

That 84% figure is calculated as follows.

There are cases where it is forecast to be clear and actually turns out clear or rain falls, and there are also cases where rain is forecast and it actually rains or stays clear.

The forecast accuracy that reflects the scores of all four of these cases is 84%.

However, the reality perceived by citizens is somewhat different.

Days forecast to be clear when they actually are clear are excluded because public attention toward the weather is relatively low on those days.

Instead, the precipitation hit rate is calculated by looking only at days when rain was forecast or when rain actually fell without any prior forecast. This figure turned out to be 0.32 for this summer.

This means it was right only about 3 out of 10 times.

Although a precipitation hit rate of around 0.5 to 0.6 is considered the limit of modern science, this summer's hit rate recorded the lowest among summers over the past decade, proving unusually inaccurate.

[Kim Wi-sang / People Power Party Member (National Assembly Environment and Labor Committee): Although the Korean numerical weather prediction model has undergone six improvements, the latest version currently in operation has recorded lower scores than the initial version from six years ago. Explanations simply stating that prediction has become difficult seem quite insufficient in many aspects.]

The Korea Meteorological Administration explained that for the month of July alone, the forecast accuracy counting only days when rain actually fell ranked second highest over the past 10 years.

The agency also stated that it will expand observation networks such as successor meteorological satellites and introduce new prediction models to boost forecast accuracy in order to do its utmost in disaster prevention.

(Photo: Yonhap News)
Reported by Shin Dong-hwan and Kim Se-kyung | Video by Jeong Yong-hwa | Graphics by Hwang Se-yeon
※ Please note: This article was translated by AI and may contain errors.