Edit in JSFiddle

if (!$.cookie('alert')) {
    $( ".announcement" ).show();
    $(".close").click(function() {
        $( ".announcement" ).fadeOut( "slow" );
        // set the cookie for 24 hours
        var date = new Date();
        var minutes = 1;
        date.setTime(date.getTime() + (minutes * 60 * 1000));
        $.cookie('alert', true, { expires: date });
    });
}

<script src="//code.jquery.com/jquery-1.12.0.min.js"></script>
<script type="text/javascript" src="http://localhost/forob/jscripts/jquery.cookie.js"></script>

<div class="announcement bg">Announcement <a class="close" href="#">X</a></div>

.announcement {
    display: none;
}
.bg {
    background: rgb(120, 120, 121);
    padding: 5px;
    width: 125px;
    overflow: hidden;
    font-family: arial;

 }
.close{
    text-decoration: none;
    margin-left: 5px;
    margin-top: -4px;
}
a:link, a:active, a:hover, a:visited{
	text-decoration: none;
	color: black;
	font-family: arial;
}