Forecasters warn of urban flooding as rain falls, snow melts

As snow turns to rain this week, forecasters warn of the possibility of urban flooding in Thurston County and surrounding areas and urge folks to keep street drains clear.

Temperatures crept above freezing on Sunday, and have stayed there. That combined with consistent rainfall means that snow will melt and channel water. And the water needs to go somewhere — preferably down a drain.

“Rain and heavy wet snow may result in water accumulating on roadways. In addition, water may channel through the snow from yards onto area roads. Localized street flooding possible,” reads a warning tweeted by the National Weather Service Seattle.

This can cause a greater risk of standing water on roadways, causing vehicles to hydroplane.

The week’s forecast signals an end of the wintry burst that dropped over a foot of snow on Thurston County and kept residents at home as snowplows cleared arterial roadways.

According to the National Weather Service (NWS), on Saturday, the depth of snow at the five monitoring stations in Olympia ranged from 12.3 to 16 inches. By Monday afternoon, it melted down to 7.1 to 8.1 inches.

The NWS’s single monitoring outpost in Lacey recorded snow 12 inches deep on Saturday and 6 on Monday. NWS doesn’t have recorded snowfall information for Tumwater.

Thurston County Public Works — the county department responsible for clearing roadways — provided an update on the department’s website, saying road conditions were “steadily improving” but warned of snow and slush on side streets. Side streets are the lowest priority for clearing, as road crews primarily focus on keeping routes clear for emergency services.

Additionally, power outages may occur from snow weighing down trees, causing them to fall on lines. According to Puget Sound Energy’s outage map, but Monday afternoon, there was only one outage between Olympia, Lacey and Tumwater — affecting one customer. But within the last day, pockets of other outages dotted the map, including one affecting up to 2,000 customers in Lacey.

Olympia Public Works provides a map showing road clearing updates.