They measured 0.27 microSv/h (0.027 mR/h) from the first snow in Saint Louis .
In case it contains Cs-137, it may be 746 Bq/Kg roughly calculating.
The recorder states like this below:
Iori MochizukiTypically it is difficult to measure the radioactivity of snow because its water content tends to attenuate the measurements;. However, one interesting effect we have noticed is that during active snowfalls indoor atmospheric radioactive readings tend to elevate above 2x background radiation.