Answer: A tree's age will largely determine its ability to recover from storm damage. A young, vigorous tree will be more likely to survive than an older one, though sometimes an older tree's deep roots will help it withstand the force of a flood. In general, a damaged older tree will be weakened more than a young tree receiving the same damage.
At this point, I'd cut the wounded area straight across with a saw to remove jagged bark and wood (which can be entry points for insects and disease organisms). Then wait for new branches to emerge from just below the cut.
You won't be successful in trying to graft the top back onto the trunk. It probably won't knit together well and even if it does, it will be a weak point for future Santa Ana winds. Since your tree is only a year old, you might just consider replacing it rather than waiting for it to produce new branches and a new central leader. Wish I had better news for you!
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