Come on ! Windy.com does NOT make any forecast of SO2, or of any other parameters.
They are sourced from weather models and satellite observations. In the case of sulfur dioxide the data are provided by the NASA.
https://earth.nullschool.net/ shows similar SO2 map as they use the same data from NASA GEOS-5
May be the these data from GEOS-5 are overestimated?
according to the forecast, a thunder should hit Buenos Aires between 18:00:00Z to 21:00:00Z.
It is necessary to take into account a small errors, which may occur, when it come to forecast.
We can see the anomaly in SO2 actual from the NASA data itself: https://so2.gsfc.nasa.gov/pix/special/time_sres/time_series.html
This clearly shows some crazy spikes right then and there for Eastern Asia. Look at the scale, ffs, its off the charts:
And there's also a weird data hole around Feb 2 (0 everywhere).
Doesn't mean we know what it was from, but it cannot be denied that there are/were crazy spikes in SO2 over that region recently.