I could be wrong, but just throwing this out there...dogs go through a fear stage at __weeks of age (I forget) & again around 7 months of age? (not sure).
It could also be a neighbor that comes out to smoke
(our neighbor), or a neighbor's car. Sometimes, when there's a siren, or car alarm...like far far away. Mine all stare out standing in a stance & sometimes even growl or howl & bark.
Mimi used to be terrified of thunder storms & she'll be shaking uncontrollably 10-15 mins before I could even hear a thunder miles away. She doesn't do this anymore, maybe Taffy will get used to it too, whatever it is. It could be what you said about the barometric pressure.
