If you are using Target Audience in your SharePoint environments, you must manage the Audiences in the Central Administration -> User Profile Service Application.
As a SharePoint administrator, you need to monitor the uncompiled audience every day. Here is the UI interface, where you can see the uncompiled audiences.
Go to Central Admin site- > Manage Service Application -> Open User Profile Service Application
To get the Uncompiled Audiences value, using PowerShell, the script is given below.
#put any site collection URL belongs to the User Profile Service application.
$objSite = Get-SPSite "http://sam.hr.com/sites/xyz";
$objContext=[Microsoft.Office.Server.ServerContext]::GetContext($objSite);
$objAudManager=New-Object Microsoft.Office.Server.Audience.AudienceManager($objContext);
#Total Audience minus(-) complied audience = Uncompiled Audience
$uncomiledAud = $objAudManager.Audiences.Count - $objAudManager.Audiences.AudienceCompiledSofar;
Write-Host "Number of Uncompiled Audience : " $uncomiledAud
You can copy the script given above and create a PS1 file(PFA). This will help you in designing a Task Scheduler to run once in a day and you can include the additional script to send an alert by email for the notification.
I hope it helps.