ANSWER - I always think that with any question like this it is really important to look at both sides of the coin and consider both a practical down to earth explanation and a more alternative answer. Without actually being there and in a position to make up my own mind (and even if you had a roomful of witches you may get different answers from what they pick up from the atmosphere…) it is hard to tell you for definite which is the right answer. But I think perhaps rather than me give you a definitive solution it is better for you to consider all aspects and reach your own conclusion. You are after all the person having the experience and therefore the best placed to understand it.
My mundane explanation would be that you are connecting the naturally atmospheric ambiance of a storm with the coincidence of the antler falling. Just because two events happen at the same time does not mean that they are connected… It is natural to attach more significance to something toppling over when your senses are heightened by the power of a storm. You may not have been so unnerved if the antler had fallen in bright sunshine but the dark and the noise of the storm do invite the mind to speculate that there might be a deeper meaning. Getting even more mundane now I’d also ask whether your doors and windows were securely fastened as the wind blowing in from the storm could well have been responsible.
I’ll give you a similar example that happened many years ago in my own home. My younger sister (around ten or so at the time) once asked my mother if she believed in ghosts. My mother gave the robust reply that she didn’t and at that precise moment a painting that had been hanging on our wall for over twenty years jumped off the wall. You could attach great significance to the fact that it happened at that specific moment but then it could have happened at any other time in the twenty years on the wall and perhaps gone unnoticed. This wouldn’t be enough for me to conclude it was definitely the work of spirit activity but it does give a damn good case for it. My point is that two unrelated events can happen at the same time without significance and that sometimes it is human nature to see a link when there isn’t one.
I’m not disparaging your experience but I know some witches who always want to slap a magical explanation on everything and I find it frustrating and try very hard not to do so myself. Many things do have practical explanations and it is as short sighted for a witch not to consider these as it is for the pragmatist to look for logic in everything. Our world is more complicated than either extreme will allow. Looking at something from all sides with an open mind helps us get as close to the truth as possible.
My less mundane explanation would certainly consider spirit activity. I very much doubt that living beings are the only ones to be influenced by atmosphere. Why do you think so many séances are conducted at night with dimmed lights and incense to stimulate the senses? I’d argue not just for the benefit of the living. I’d also make the observation that many spirits can be mischievous and irritating and would get a lot more about putting their energies into pranks like pushing things over when there is a good chance that the human at the other end of it is feeling unsettled in the first place. When you consider the degree of effort it would take for a spirit to move anything (and opinions are divided as to whether this is possible at all) then I think if I were a spirit bent on scaring the living I’d hold fire until the right conditions came along as well.
A storm can have a real effect on the energies in the air and sometimes it can sweep away so much of the stable energies that it can leave behind it a sense of emptiness. It may well be worth taking back control of your space and building back up the energy levels you are accustomed to working in. A good cleanse of the space (good old sage smudging…) will dissipate some of the negative vibes and leave the place feeling yours again. I doubt this is anything more sinister than a touch of negative energy, easily cleansed and cleared away.
I’ll just finish with the advice though that if something doesn’t feel right then likely it isn’t. No matter what your level of experience from absolute novice to seasoned practitioner there are things you can do to affect changes in your own space. Cleansing is one of them but sometimes just standing your ground and openly asserting your possession and dominance of the space is enough. You wouldn’t let an uninvited stranger into your home - take the same attitude with passing spirits. This is your space and your home and anything that comes in, living or dead, does so on your terms.