Trick-or-treating in Washington state could be disrupted by an incoming atmospheric river on Friday.

The storm is expected to hit the coast on Halloween. The greatest threat with the incoming storm will be heavy rainfall, NWS meteorologist Dev McMillian told Newsweek . Locally gusty winds also could pose a hazard.

Why It Matters

Atmospheric rivers are a "long, narrow region in the atmosphere—like rivers in the sky—that transport most of the water vapor outside of the tropics," according to the National Oceanic and Atmospheric Administration (NOAA).

The storms brought by atmospheric rivers are known for their heavy snow, heavy rain and strong winds. They more commonly affect the West Coast, particularly during the winter months. Although the storms can bring beneficial snow that

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