[ORE] How to build a specific power: Alternate future sight

So I want to build a power that's sort of like Precognition but I think a little more flexible and I wonder what I could do to model it.  I got the idea from the Short Story Six Months and Three Days by Charlie Jane Anders.  It's a great story about two precognitives who date.  One is a man who sees an unflexible future he can't change and the other is a woman who sees all the myriad ways her own personal timeline could play out.  She can't see other people's future except in ways they intersect her own life.  But she can picture timelines where she goes on spontaneous European vacations complete with what torrid affairs she would enjoy if she took the trip.  She keeps her charity open by figuring out what grants she'll get if she applies and keeps it afloat if not awash with money.   And she see's pretty far into the future as well, including a death scene that could only come after a long, well lived life and that's what she keeps aiming for when making decisions.  She's very good at decision making because she sees so much.  She's not perfect, but she is very powerful.  I'm interested in modeling that power.  So how would I do it?