How system is calculating ExPost Values

Hi Experts,

Could you please help me how below values are getting populating.

History Ex-Post

Jan 2,000

Feb 1,520 2,000

Mar 2,000 1,856

Apr 2,520 1,899

May 1,520 1,899

Jun 2,520 1,899

Jul 1,520 1,865

Aug 2,500 1,762

Sep 1,500 1,791

Oct 2,500 1,704

Nov 1,500 1,943

Dec 2,000 1,810

I am using Forecast model with parameters: Constant model 10

Alpha- 0.30 & Sigma- 1.25, Outlier- Expost

Could you please help me on the same.

Thanks

Hitesh