Satellite Accuracy video by Ken Sauret

Lowrance Satellite accuracy

I think it has more to it than that. It also is affected by how many satellites your unit is tracking as well and likely their positions.

You’ll notice when you start your unit up, the EPE is high and will get lower as it locks on.

I always display EPE on my units to get an idea of how accurate my current position is.

The presenter doesn’t understand satellites and how they operate very well it seems. Atmospheric conditions actually play a very small part in satellite accuracy other than a thunderstorm close by which can disrupt satellite signals if lightning is involved.
Like ottomatica says, the number and position of GPS satellites plays a part, but the accuracy is more a product of the differential correction source which in this case is WAAS. Space weather also plays a large part in position accuracy and solar flares can play havoc with the satellites and cause solar storms which will actually move the satellites slightly in their orbits and may cause position calculations to be slightly off.