[transatlantic38]

It's a deliberate decision to convey immediacy and urgency. Using present tense makes the memories read as closer and still unknown territory instead of farther removed and already determined, which matches the emotions of the memories that the author is trying to convey.

Consider the emotional difference between:

> It is summer, and the ice cream is melting.

> It was summer, and the ice cream melted.

These types of literary choices are a core part of writing prose at an advanced level the same way that camera angles and color palettes are a part of cinematography. Grammar "rules" don't really exist in creative prose, it's ultimately about using words to convey meaning however you can.