  We examine Saturn's atmosphere with observations from ground-based telescopes
and Hubble Space Telescope (HST). We present a detailed analysis of
observations acquired during 2018. A system of polar storms that appeared in
the planet in March 2018 and remained active with a complex phenomenology at
least until Sept. is analyzed elsewhere (Sanchez-Lavega et al., in press ,
2019). Many of the cloud features in 2018 are long-lived and can be identified
in images in 2017, and in some cases, for up to a decade using also Cassini ISS
images. Without considering the polar storms, the most interesting long-lived
cloud systems are: i) A bright spot in the EZ that can be tracked continuously
since 2014 with a zonal velocity of 444 m/s in 2014 and 452 m/s in 2018. This
velocity is different from the zonal winds at the cloud level at its latitude
during the Cassini mission, and is closer to zonal winds obtained at the time
of the Voyager flybys and zonal winds from Cassini VIMS infrared images of the
lower atmosphere. ii) A large Anticyclone Vortex, here AV, that formed after
the GWS of 2010-2011. This vortex has changed significantly in visual contrast,
drift rate and latitude with minor changes in size over the last years. iii) A
system of subpolar vortices present at least since 2011. These vortices follow
drift rates consistent with zonal winds obtained by Cassini. We also present
the positions of the vertices of the North polar hexagon from 2015 to 2018
compared with previous analyses during Cassini (2007-2014), observations with
HST, and Voyager data in 1980-1981 to explore the long-term hexagon's drift
rate. Variations in the drift rate cannot be fit by seasonal changes. Instead,
the different drift rates reinforce the role of the North Polar Spot that was
present in the Voyager epoch to cause a faster drift rate of the hexagon at
that time compared with the current one.
