Try out this:
~~~
open hamilton
list PM = seasonals() ^ PC6IT
list L = PC6IT*1
#tsplots L --output=display
gpbuild Plots
loop foreach i L
gnuplot $i --with-lines --time-series
endloop
end gpbuild
# Adjust parameters as you feel
gridplot Plots --fontsize=10 --width=1000 --height=600 --cols=3 --output=display
~~~