bootstrap警告框隐藏和显示

如何在发生一个事件后弹出一个警告框，而警告框本身是隐藏的

<div class="alert alert-block">
<button type="button" class="close" data-dismiss="alert">&times;</button>
<h4>Warning!</h4>Best check yo self, you're not...
</div>

---

JS

$('#alertTest').modal({
    backdrop:true,
    keyboard:true,
    show:true
});
return false; 

HTML

<div id="alertTest" class="modal hide fade" tabindex="-1" role="dialog" aria-labelledby="myModalLabel" aria-hidden="true">
    <div class="modal-header">
        <button type="button" class="close" data-dismiss="modal" aria-hidden="true">×</button>
        <h3 id="myModalLabel">提示标题</h3>
    </div>
    <div class="modal-body">
        <p>提示内容！</p>
    </div>
    <div class="modal-footer">
        <button class="btn" data-dismiss="modal" aria-hidden="true">关闭</button>
    </div>
</div>

---

<div class="alert alert-block hide" id="warning-block">
    <button type="button" class="close" data-dismiss="alert">&times;</button>
    <h4>Warning!</h4>Best check yo self, you're not...
</div>

<script type="text/javascript">
    $("#warning-block").show();
</script>