How can I create a screen prompt to force users to enter a value into a field?

We currently have a validation rule that if the Opp is Closed/Lost the user needs to enter the Lost Reason. Although the user needs to go back to the record and update the picklist. 

I would like for the Lost/Reason field to be prompted in the page after the Opp record was saved as Closed/Lost without a Lost Reason.

Can I do this with Flows #Flow