The following portion of a debate on Open Theism/Reformed theology has Brian Enyart absolutely destroy (exegetically) Brian Schwertley (Reformed) on the topic of prophecies in the Bible that failed (some were conditional; some were not presented as being conditional):
Enyart on failed Biblical Prophecies
For more on the contingent nature of prophecy and related topics (including the anti-biblical nature of Calvinism), see:
Resources on Joseph Smith's Prophecies (contains a listing of LDS and non-LDS sources on the contingent nature of prophecies, such as Richard L. Pratt (non-LDS [Presbyterian] scholar), "Historical Contingencies and Biblical Predictions")
An Examination and Critique of the Theological Presuppositions Underlying Reformed Theology
Enyart on failed Biblical Prophecies
For more on the contingent nature of prophecy and related topics (including the anti-biblical nature of Calvinism), see:
Resources on Joseph Smith's Prophecies (contains a listing of LDS and non-LDS sources on the contingent nature of prophecies, such as Richard L. Pratt (non-LDS [Presbyterian] scholar), "Historical Contingencies and Biblical Predictions")
An Examination and Critique of the Theological Presuppositions Underlying Reformed Theology