Final answer:
Emily Dickinson means that the storm must be very powerful.
Step-by-step explanation:
When Emily Dickinson says 'sore must be the storm-that could abash the little bird,' she means that the storm must be very powerful.
The word 'abash' means to make someone feel embarrassed or ashamed, so the storm must be so intense that it could make the little bird feel intimidated. This suggests that the little bird is resilient and brave in facing such a powerful storm.