Predicate in wait only called once when using notify in loop

When calling the notify_once method on a condition variable within a loop in one thread, it appears that the wait method in another thread only checks it predicate once. Example code is listed below:

int someNumber = 0;
mutex numberMutex;
condition_variable cv;

void waitFunction()
{
  unique_lock<mutex> lock(numberMutex);
  auto duration = chrono::seconds(5);

  // Predicate is only called once?
  cv.wait_for(lock, duration, []() {
    cout << "Checking condition: 10 == " << someNumber << '\n';
    return someNumber == 10;
  });
  cout << "Done with this thread...\n" << flush;
}

int main()
{
  thread waiter(waitFunction);

  for (size_t number = 0; number != 50; ++number)
  {
    {
      lock_guard<mutex> guard(numberMutex);
      someNumber = number;
    }
    cv.notify_one();
  }

  waiter.join();
}

Executing this program gives the following output

Checking condition: 10 == 49
Checking condition: 10 == 49
Done with this thread...

while I would expect it to check the condition at each iteration.

How is this possible?