I can't tell what I'm looking at. It appears this is a drywall tape rip, and that may have been only a single layer of seam tape. On seams between drywall panels, about 3 tape layers are used.

That crack could have been caused by the storm if the wind was strong enough to flex the house. Another factor might have been stairway loading. If a very heavy item was taken up the stairs, or a heavy item dropped on the stairs, there could hae been flexure that tore the tape. It does not look dangerous, mostly cosmetic. If the staircase is flexing, that should be fixed else you could expect the repair to rip as well (unless the repair material has enough pliability to accept small motions).

Thanks!! I am closely monitoring that crack now, hopefully it won't expand.

Just to be clear, there was a crack there already, or more precisely a joint, between two pieces. You're just looking at cracking of the plaster used to fill it. Not nearly as bad as cracks appearing where there were none to begin with.

What would you suggest to fix/fill this crack? I am also seeing another crack on the second floor ceiling right above the crack on the stair ceiling:

Any idea if this is cosmetic too? I don't see any joints here but the location is the same as the one on the stair, vertically.

The notion that if a crack appears at a joint it is indicative of a less severe problem then if the crack had appeared mid-panel is simply wrong.

If two perpendicular plane surfaces are moving relative to each other the crack may appear at the taped joint - and, no taped joints do not normally have "about 3 tape layers ..."

Also, in an eighteen year old home if you had a high wind that "the wind was strong enough to flex the house" you certainly would have noticed it and as it presumably was the biggest storm of the last eighteen years you'd probably remember the storm's name.