Order an array with Jekyll / liquid template

I'm trying to do the following.
I use Jekyll to create a list of posts, and ordertem by category (monday…sunday)
I'd like to have them displayed in chronological order but Jekyll order them alphabetically.

Is it possible to sort an arry with Jekyll?

I have added an order key to the post yaml to mirror monday = 1 … sunday = 7

I'm trying to then sort the array with this order key, bu it doesn't work.

  {% for post in posts_collate  %}
    {% capture class %} {{ post.tags | first }} {% endcapture%}
    {% capture club %} {{ post.tags | last }} {% endcapture%}

    {% if forloop.first %}
      <h2>our events</h2>
      <h3>{{ class }} & {{ club }}</h3>
      <dl>
    {% endif %}
    {% if post.rel == 'me' %}
      <dt>{{ post.category | sort: 'order' }}</dt> 
      <dd> <a href="{{ BASE_PATH }}{{ post.url }}">{{ post.title }}</a></dd>
    {% endif %}

    {% if forloop.last %}
      </dl>
    {% endif %}
  {% endfor %}

And i can't find any info in the big google machine, so i'm not sure thay it is possible.