Yes, there are several patterns that tend to occur in the troposphere prior to an SSW. These are explained in detail in a previous post: https://www.climate.gov/news-features/blogs/polar-vortex/cooking-strato….

For a more specific case, the 2021 SSW was preceded by a persistent low pressure weather system over the North Pacific and high pressure weather system over the North Atlantic and Eurasia. There was also a bomb cyclogenesis over the North Pacific that may have further reinforced that pattern, giving an extra nudge to the stratosphere (https://www.climate.gov/news-features/blogs/enso/sudden-stratospheric-w…).

We haven't talked about it yet, but the Arctic Oscillation, which represents the see-saw of pressure between the pole and the mid-latitudes (https://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao…), can also influence the stratospheric variability. We'll talk more about it in a future post.