Another answer has competently dealt with the prophetic aspect asked for in the question. I want to look at the symbolic aspect, asked for in the question, regarding the darkness during the crucifixion of Jesus Christ.
There were ten occurrences which are significant (Matthew 27 and Luke 23) :
- There was darkness over all the earth (ge) for three hours
- The sun was darkened
- The veil of the temple was rent
- Jesus cried with a loud voice
- Jesus commended his spirit to the Father
- Jesus expired (expneuma)
- There was an earthquake
- Rocks were rent
- Sleeping saints arose out of the grave
- A Roman centurion testified "Truly this was the Son of God"
I would say there are five symbolic aspects regarding the darkness. The symbolism is made clear by reference to the ten events above.
A - The Rift Within Deity
One of the cries from the cross was 'My God, My God, why hast thou forsaken me ?' which indicates the separation which occurred when Jesus Christ, through the eternal Spirit (Hebrews 9:14) offered himself up as the Sin-Bearer. The darkness over the earth symbolises this terrible separation of him from his Father.
B - The Death of Christ
Mankind, in Adam, having done all that was done - in the ancient world, in Israel, among the gentiles - added this wickedness above all, that humanity on earth rejected the Son of God. I believe the darkening of the sun symbolises the reaction of heaven to such an atrocious rejection from earth. Although men did not deliver the actual death-blow (for he yielded up his life, himself, John 10:18) yet they, having crucified him, are not exempt from the crime of homicide.
C - The End of Israel
That the veil of the temple was rent indicates the end of all the representation on earth of things in heaven. But Israel had rejected the very one sent to realise all the representation. It was a dark day indeed for Israel, now that Israel had rejected that which they had been supposed to revere in figure.
D - The Invisibility of What Occurred in the Darkness
In the Gospel is the righteousness of God revealed, Romans 1:17, says Paul. He makes it clear that by one righteousness is there justification and that this righteousness (dikaiomatos, Romans 5:18) is a demonstrated righteousness. The demonstration was in darkness. Human eye could not see it. What was done at Golgotha is revealed in the Gospel.
E - The Portent of the End of the World
Coupled with the earthquake (an instability in the earth) and the rending of rocks (an instability in matter itself) the darkness is symbolic of the end of all things. The sun shall be darkened prophesied Jesus, Matthew 24:29, at the end of time. What occurred in his departure from the world (for after his burial the world saw him no more) is a portent of what shall accompany his return, in judgment.