Why is it so hard to forecast lowland snow around the Puget Sound area?

SEATTLE — Wintry weather arrived in full force this week, and some area cities saw several inches of wet snow accumulate Tuesday night. In some places, people may have woken up Wednesday to more or less snow in their backyard than what they saw in the forecast.

That’s because the conditions are variable, said Mary Butwin, a meteorologist at the National Weather Service in Seattle.

“It’s difficult for everyone that forecasts for this area,” she said. “It’s one of those things where it will change and you have to stay up-to-date on it.”

In the mountains, snowfall is pretty reliable by elevation. But in the lowlands, varying topography, proximity to bodies of water and the way the storm systems move all come into play.

Cities at higher elevations will typically see more accumulation. Water temperatures are usually warmer than air temperatures in the winter, so areas near bodies of water may see less snow stick. And wherever there’s colder air, the precipitation is more likely to come down in the form of snow.

Meteorologists may update weather advisories based on the rate of precipitation and accumulation.

When there’s snow in the forecast, it could change every day, Butwin said. Residents should keep up to date with the latest projections to have a better idea of what could come.