From a Reformed perspective, does retroactive prayer makes sense? From a reformed perspective, that God is outside of time, does it make sense to pray for something that already happened? Or, can a prayer cause God to impact time in a retroactive way?

An example could be: let's say your wife will be travelling to some other country from 3pm to 6pm. At 6:30pm you don't have any news about her, so you pray something like: "God, please take care of her, and I ask you that, if this is your will, no bad thing had happened".

Does this prayer makes sense from a reformed perspective? I mean, since God works outside of time, could you pray for something that already happened? 

If this makes sense, have the Bible or the tradition any example of this kind of prayer? 

If there is disagreement in reformed views about this question, a good answer would contain an overview of the differences.

Disclaimer

I'm not asking if "the act" of praying retroatively is OK, because this is a matter of opinion. What i'm asking is: "is praying for something that already happened theologically accurate, taking in consideration the reformed view of predestination and God's relationship with time?"
To me, this question boils down to the following:


Is it logically possible that "prayers for the past" or "retroactive prayers" are efficacious, given a Reformed perspective


In other words, does it make any sense (either logically or theologically) to pray for something which might already be "set in stone" as a part of history.  I address that in the first part, but then address the question of the real purpose of prayer and/or why we might even want to pray for God to change the past in the first place.



According to Kevin Timpe in Prayers for the past,


  All three of the world’s major monotheistic religions traditionally affirm
  that petitionary prayers can be causally efficacious in bringing about certain states of affairs.


However, there are different meanings of efficacious.  He quotes David Basiger in The Case for Free Will Theim (InterVaristy Press, 1996) as laying out 3 different ways that petitionary prayer can be efficacious:


  
  Petitionary prayer can beneficially affect the petitioner herself.
  Petitionary prayer can beneficially affect people who are aware that
  petitions are being made on their behalf.
  Petitionary prayer affects whether or not God directly intervenes in
  the world.
  


Kevin then goes on to address only the 3rd question - whether God can directly intervene in the world based on a retroactive prayer.  I believe this is the core of your question, but part of the answer is to realize that prayer has effects and reasons beyond God changing something in our world.  I will address this point at my conclusion and stick to the question of intervention for the moment.

He explores the matter of God being able to intervene in a past event from several different philosophical perspectives which all assume libertarian (incompatibilist) free will.  His conclusion is that:


From a logical viewpoint, the philosophical frameworks of simple foreknowledge, eternalism, and Molinism all support the logical efficacy of prayers directed at past event.
He also concludes that Openism (or Open Theism) is not logically consistent with past-directed or retroactive prayers.  This stems from the fact that Open Theism essentially argues that the future is not set, but the past is, and that God is a temporal being who knows all possible outcomes, but at a given point in time does not genuinely know the future.


The views of simple foreknowledge and Open Theism consider God to be temporal, and thus not "outside of time".  These are therefore incompatible with your question, so I will not address them further.  I believe eternalism and Molinism can roughly be grouped together, but the reader can pursue the distinctions further if desired.  C.S. Lewis, as an example, argues for the potential efficacy of past-directed prayers based on an atemporal nature for God.

The long and short of the analysis is that from a logical perspective, prayers for the past can cause God to intervene and change events, but only to the extent that they have not already be set in place or that we have knowledge of them. 

For example, it does not make sense to pray for a different outcome to the battle of Waterloo, because it occurred well over a century ago, and is settled history.  However, if I become aware of a natural disaster which killed some people in a location where a family member lives, it may be efficacious to pray for that as the point is not "fixed" and all information is not known.  At this point God could logically still "change" the event from our perspective as temporal beings in the timeline.

Of course, the logical solution to the problem is that if we pray now for a past event, God would have known that and changed the event in the past based on knowing our future prayer.  A perfect example would be a prayer for the present that God provide for bills that are due tomorrow.  I receive a check in the mail that is just enough to cover them, today, but the check was sent a week ago.  Was that an answer to prayer?  Maybe, maybe not, but it 100% could have been...



What is the Relevance of This Conclusion?  The real answer...

I understand this viewpoint, and have no problem with the logical arguments he puts forth, but I do think this is all a little off the mark with respect to the real question.

If you search the scriptures, there are no examples of past-directed prayers.  In fact, there are very few examples (if any real ones) of true future-directed prayers.  I think this is the key to the real answer to the query.

The real answer goes to the purpose of prayer and how God interacts with his people.  All of the Bible describes God's love for mankind and him creating them to have a purpose of being in relationship with him, glorifying both God and his creation.  The purpose of prayer is intimately tied to that relationship.

Prayer appears to function as a way of enhancing our relationship with God.  While it is used as a means of furthering our sanctification, working out our salvation, etc., it is clear that even sinless humans are intended to pray - there are a multitude of examples of Jesus praying frequently and intensely to God the Father.

God wants to interact with us right now in time, about how we are living for him and what his will is for us at this moment. We, with Jesus as our example, should be asking what are the words and actions of the Father that he desires of us.  What is his will for us at this moment in time.  It is true that he wants us to bring our petitions to him, but even then we should pray as Jesus did - "but not my will, but yours be done".

Thus, my ultimate answer is that yes, past-directed prayers can be theologically sound, and while God can and does answer prayers (past, present, and future directed), our focus should be much more on simply sharing our hopes and fears with him, and seeking his will and guidance through his Spirit, while resting and rooted firmly in Jesus Christ, with him as our example.