Flood Measurements

We have pretty bad flooding right now in the south of Poland. There are predictions by Instytut Meteorologii i Gospodarki Wodnej (IMGW), Polish weather institute, about peak height of flood wave on Odra in Wrocław and they’re so inaccurate that they’re doing disservice to citizens. IMGW had predicted the peak height anywhere between 550-710 cm. Yesterday they changed their predictions first to 550 cm, then to 600 cm and said that Odra will reach its top height around 00:00 - 02:00 AM. It’s 12:30 now and flood wave has reached 640 cm and counting. The time of reaching that peak height is uncertain as well, because it had changed so many times and was everything between Tuesday (2 days ago) and late Saturday.

People rely on these predictions for many reasons. Today even Polish Prime Minister Donald Tusk got angry about inaccurancies.

It’s a lesson which I have learned during the first year of university, roughly 17 years ago: you ALWAYS tell a measurement AND accuracy of your measurement. “Peak wave will reach 600 cm” and “peak wave will reach 600 cm ±50 cm” are two totally different informations and people will react differently to them.

We have a long history of silently acknowledging that forecasts are inaccurate. In the 90s we joked that when there’s a sunny forecast in TV, you should prepare an umbrella. I think that in 2024 we should no longer accept this status quo. If you can’t make useful forecasts, then don’t make them at all and stop wasting public money.