Cacher is the code snippet organizer for pro developers

function replace_howdy( $wp_admin_bar ) {
    $my_account=$wp_admin_bar->get_node('my-account');
    $newtitle = str_replace( 'Howdy,', 'Welcome,', $my_account->title );
    $wp_admin_bar->add_node( array(
        'id' => 'my-account',
        'title' => $newtitle,
    ) );
}
add_filter( 'admin_bar_menu', 'replace_howdy',25 );