Undoubtedly good advice about getting specific help on the DL forum. BUT, I think there is a global issue here as well. There have been many flights I've had cancelled where the official excuse was 'weather' - at least that's what the passengers in the area were told. I have suspected on several of these that weather was not at all the reason, and that perhaps they were stating this precisely to avoid anyone trying to exercise Rule240. Notable in my memory was a flight to BOS where there was no weather anywhere on east coast.. none in the departing city, clear as a bell in BOS, no thunder boomers anywhere on the weather channel (which I watched while cooling my jets in the US club for several hours waiting for the next flight).

Do you think this happens? And how can you verify the real reason - since I would think they couldn't get away with using a false weather claim in any official way.