Moving weld up and down smoothly with tweenservice?

I’m working on this tornado script, and I made a trail that goes up and down as the tornado spins. So the problem I’m having is whenever I make any up/down script with tweenservice once it does a full loop, it look like it is bouncing up and down.

This doesn’t fit the vibe for the tornado, does anyone know how I can fix this?
Code:

local track2 = TweenInfo.new(1, Enum.EasingStyle.Linear, Enum.EasingDirection.In, -1, true, 0)
local surround = tornado:WaitForChild("Sorround")
local trailx = surround:WaitForChild("TrailX")

local playtrack2 = ts:Create(surround.Weld, track2, {C0 = surround.Weld.C0 + Vector3.new(0,0,10)})
playtrack2:Play()
playtrack2:Destroy()

Could you please send a short video, or even a picture to show what you mean? Thanks :smiley: