^11:19 Then God’s temple in heaven was opened, and within his temple was seen the ark of his covenant. And there came flashes of lightning, rumblings, peals of thunder, an earthquake and a severe hailstorm.

Then God’s temple in heaven was opened,

The Revelation of Jesus Christ is an "opening" book:

What has been hidden from us and the earth in the spiritual realm is slowly revealed. With the revelation comes an awareness of God's purity and holiness. The result of the encounter with purity and holiness is judgment against sin and the devil (Revelation chapters 12-16).

Since the temple is the place of worship, this encounter is a worshipful experience. John saw parts of this temple previously: throne and sea of glass (Revelation 4:6); and altar (Revelation 6:9, Revelation 8:3-5); and service by tribulation saints (Revelation 7:15).

Isaiah saw the throne and temple in Isaiah 6:1. Paul indicates this temple is where Christ now is ministering as High Priest (Hebrews 8:1-7). Recall, Christ as the untimate sacrifice is able to be this High Priest, Hebrews 9:23-26.

and within his temple was seen the ark of his covenant.

The ark with its mercy seat (Exodus 37:1-9) speaks to atonement for sin. Thus this typifies Christ; the law, manna, and Aaron's rod contained therein show man's dependence/imperfection with respect to God.

In the Old Testament, the last reference to the ark occurs in 2 Chronicles 8:11. Later, Solomon with his involvment with Pharoah's daughter, Queen Sheba (Ethiopian), gave "all her desire (2 Chronicles 9:12) including perhaps the Ark. Ethiopian history claims the Ark is guarded in a church in Aksum, Ethiopia.

Isaiah has a prophesy in Isaiah 18:1-7 which may indicate the return of the ark. The 'standard' in verse 3 (nes in Hebrew) could be translated as 'ark'. Likewise, the 'gift' (nes, again) in verse 7 is returned 'to the place of the name of the Lord of hosts'.

And there came flashes of lightning, rumblings, peals of thunder, an earthquake and a severe hailstorm.

Compare this to events at the temple at Christ's death, Matthew 27:51.