For this scenario, we'd likely see something like an initial breakdown of Bitcoin Dominance and breakout of Alts vs. their Bitcoin pairings, followed by a pullback on both as Bitcoin rises higher and alts lose vs. BTC again, hitting higher lows near bottom prior to the real breakout.
In this example, there's a breakout above recent Bitcoin Dominance highs (weekly close(s) above 54.09%), and alts breakdown losing their current bottoms vs Bitcoin (weekly close(s) below their weekly lows). Then a pullback below 54.09% and above alt's recent lows leading into an extended alt season.