It's not the same at all.
Weather forecasting is running mathematical models through a simulator, looking for convergent outcomes, and assigning probabilities to them. It is mathematics based on science. It is not always accurate -- that is the nature of probability; and the models can always be improved.
Technical analysis is based on the assumption that markets are predictable in behaviour. TAs will tell you that they are modelling market emotion. However they are not -- you will never see any such model presented. Rather they are using patterns in historical price and volume to predict future price and volume. Usually based on premises (such as Eliott Wave) that are 100 years old.
You will see lots of fancy indicators -- however they are all based on the same raw data: historical trades (There is no other data available). They are not even remotely modelling the underlying users and markets at play.
Finally, another way that TA and weather forecasting is different... consider this. If TA could even remotely accurately model behaviour, the behaviour itself wouldn't happen and the price wouldn't move. This is the key as to why TA is effectively worthless. Is the TA influencing the market, or the other way around? Read around and you will soon realise it is the former. TAs are only market oracles to their herd of market sheep.
Yes, comparing TA to weather forecasting was a bad example, as you have described.
TA is not effectively worthless, as you have stated, because I have used TA to make profitable trades. If I did not use TA, I would be stuck in a losing trade right now.
You don't know that. It could be simply luck, maybe there are just as many people making losing trades using their TA but only the profitable ones will post here about the wonders of it.
Successful traders use it every day to make money trading stocks, commodities, and currencies. I don't understand how you can say it's worthless. You have people on Wall Street, working for immensely profitable institutions such as Goldman Sachs and Morgan Stanley, and their only job is to trade. These companies recruit from universities such as Harvard, Yale, you name it. And what do they teach them? TA. What do they use to trade? TA. These hotshot traders make those trades with TA and bring in the dough and help make these banks rich. Why would GS hire traders and teach them TA if it was worthless?
Perhaps TA only works when enough people use it and interpret it the same way? If you get enough sheep to follow your method it will automatically become a succesful trading strategy. Not so sure if that's the case in bitcoin, it's kind of a different creature with lots of inexperienced traders who stubbornly follow their own method like myself.
First, let me say relying just on TA with BTC is risky but I do use it a lot.
TA for sure works. That is not really the question, the question is how often and how accurately. Looking at my (past) record, I'd say it works more times than not and a lot better than guessing. That has been proven over many many years.
If anyone thinks TA doesn't work I'd say you have to try it for a few months after learning it pretty well (spending a couple hundred hours studying and practicing).
To define how it works, that is a tough one. The underlying things we see in a chart are composed of many variables (e.g. emotion, economics, fundamentals (yes!), etc.)
So, I use TA but with BTC I am a lot more careful with it as a lot of BTC is driven on sentiment (aka The world situation). We could be going down fairly hard and if another country pulls a Cyprus - BOOM UP. And vice versa in a sense. But I think all of us know that, the thing is, the world is a tough place today. Some currencies/economies are getting closer and closer to collapse by all accounts and to me, that will be the real determiner - after all it is in large part why BTC is where it is.