Short cabin in the woods story involving a monster and two kids

Question

The family visits their/a cabin in the woods. The kids see a local who tells them about the monster residing in the woods. It proceeds with them spotting weird things, indicators that there is indeed a monster.

Sun sets and the monster is real, it's pursuing the kids as they rush back to the cabin but the monster catches up and simply hands over a jacket, left behind by the son at the lake.

I do remember distinctively that as a ten year old I found the language employed very good and the build up was excellent.

• I remember that the monster was called The Watcher/The Sentinel but do not remember exactly. Searching those two terms haven't yielded anything worthwhile as there are countless number of horror stories titled The Watcher.

• I chose this story for a storytelling competition in 2013 (that means I was 13 years old back then not ten).

• I may have given the impression that it was a kid's story, it is not.

• All of this was before the era of creepypastas.

Answer 1

Super late answer but I think I found it: "Duffy's Jacket" by Bruce Coville. I had to dig it up from an old school book of mine. I came by this question because I was searching for this story as well.

It can be found in Spooky Stories for a Dark and Stormy Night:

The figure stepped into the room. Its head nearly touched the ceiling.
Marie squeezed against my side tighter than a tick in a dog's ear.
The huge creature sniffed the air. It turned in our direction. Its eyes seemed to glow. Moonlight glittered on its fangs.
Slowly the Sentinel raised its arm. I could see Duffy's jacket dangling from its fingertips.
And then it spoke.
"You forgot your jacket, stupid."
It threw the jacket at Duggy, turned around, and stomped down the starir.
Which is why, I suppose, no one has had to remind Duffy to remember his jacket, or his glasses, or his math book, for at least a year now.