Modelling advice needed

 From:  TOM (SIRTOM)
8228.1 
Hi MOIers,

I attached a file and a screenshot of a modelling challenge I am currently facing.

Version a1 to the left shows a shape where the profile is gently fading out vertically,

What I want to achieve is depicted on the right (a2) - the same profile fading out gently
but the fade out should end in an arc and then progressing linearally.

Difficult to explain but I hope you got it.

Thankful for tips ! Tom

EDITED: 22 Dec 2016 by SIRTOM

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