The pacific decadal oscillation is the 20 year cycle of the air above the pasific ocean near the equator off the west coast of mexico, this cycle is split into 2 categories: El Niño (when the air above the pasific ocean is warmer) and La Niña (the colder counterpart).

Focusing on the impact this has on the continental US: El nino, the warm one, pushes the pacific jet stream to the south, which results in significantly more rain in the southern US and dryer and warmer conditions in the northern US.

La nina, the cold one, pushes the pacific jet stream up north, which results in dryer conditions in the southern US and colder and more rainy conditions in the north.

So fun thing about this cycle: it's effect on the American north east are less cut and dry and even more so, maryland is basically on the boarder of what's considered north and south when it comes to climate in the US.

That being said, generally speaking, there is a pattern that can be established where El nino years mean maryland gets colder winters with more rain and snow, while la nina years mean more tame winters for maryland with warmer temperatures and dry conditions. In other words we're more like the south than the north for this cycle.

We have been in a la nina state since around 2018, and I belive that's why we haven't been getting any snow. The winters have also been warmer these past couple of years.

Don't take what I say as absolute fact btw, that's just good internet advice in general though.