Anyone who has followed President Erdogan's career since 2002 could be surprised by the snap election decision because in the past he has denounced early elections as either a sign of underdevelopment or of treason. Despite this framing of it, he had to call snap elections almost two years before the scheduled elections. Some analysts argue that this is just Erdogan's strategic vision to ambush the opposition. I see it more as a decision he had to take under duress.
When we look at the Turkish economy, we see major signs of trouble brewing: devaluation of the Turkish lira, a current account deficit, record-high inflation. I think Erdogan realized he can't wait until November 2019 for the elections, and he'd better call elections while the economy was still surviving on life support.