I have to agree, Jason, that on the Oregon coast dealing with recent storms, just putting a secondary cover over your vent is lipstick on the pig. Wind blown rain is likely either invading past a compromised rubber lid seal (assuming your lid is closed during storms) or entering the inner roof via an adjoining fixture or wire entry that needs new flowable Dicor. Been there, done that. Take Gerald’s and David’s thoughts seriously.
If you affirm there is no other culprit and insist on leaving the lid open for ventilation during storms (I do not), then a MaxxAir or other cover may be advisable.
Joel