How to use jQuery to make a Django Alert appear (sliding down)

The following script is working fine to fade out my Django alert:

 <script>
        $(document).ready(function(){
            window.setTimeout(function() {
        $(".alert").fadeTo(500, 0).slideUp(500, function(){
          $(this).remove();
      });
    }, 2000);
    });
</script>

But the following is not working—I’m just trying to do the opposite here: make the Django alert appear by sliding down. How can I make the below work?

<script>
        $(document).ready(function(){
        $(".alert").show().slideDown(500, function(){
      });
    });
</script>