Godrulz, is this future 'great tribulation' going to be the result of cumulative contingencies gone haywire or the direct meticulous intervention of God?
You really should ask google or wikipedia. They seem to have all the answers?!
My wife asked who my favorite TOL poster/buddy is. I said I have most kinship (belief and heart) with Philetus and muzikman (though we disagree on various things). Take it as a compliment. Even though you were cut out of my will, I trust I am still in yours.
The scope of Rev. 6-19 (Tribulation...Great Trib. may only refer to the last 3 1/2 years) is general in some ways, so cumulative contingencies (whatever that means) will affect the details of that yet future period. Remember our two motifs? God predestines some vs all of the future. The exact details or individuals during this period are not foreknown nor predestined. Whether a current world leader, for example, would manage to stay alive until this starts is not settled. What is predestined is the chronology of the seal/trumpet/bowl judgments (i.e. God predestines, knowing that the Gentile nations will be judged, the specific judgments). The Second Coming of Christ in Rev. 19 and start of the millennial kingdom is also predestined and predictable because God will bring it to pass by His great ability. Whether Joe is here or there or whether a dog barks or not during this time is irrelevant and unknowable as a certainty. The 144,000 super Jewish-Christian evangelists can also be raised up by God as predetermined without knowing who will be part of this number from before they are born (cf. we are predestined as the Church to be the people of God, conformed to Christ's image, without individuals being predestined from eternity past as to who eventually believes or not).
So, Open Theism, unlike simple foreknowledge or determinism, can support the motif of God deciding to do certain things during this future period (whenever He intervenes and history moves sufficiently in the general direction) without these events being seen or determined in exhaustive detail.