I was curious but it’s surprisingly hard to find info. These guys [1] are pretty stoked about “nowcasting”—which seems to be on sub-10-minute timescales to issue local severe weather warnings and such. It appears current sounders don’t scan as often.

This project ppt from 2011 [2] references different requirements for different areas/teams and shows the instrument spits out readings at 150 Mbit/s, which seems like a good clip. Overall it sounds like a lot of local knowledge is involved in turning this output into forecasts. Maybe there’s not a precise answer to your question.

Somebody else must know more.

[1]: https://www.eumetsat.int/features/think-global-act-local

[2]: https://www.researchgate.net/profile/Donny-Aminou/publicatio...