Wet weather may bring river flooding, Weather Service warns

The News Tribune

Western Washington residents may welcome warmer, wetter weather this week, but that presents a potential problem: flooding.

Heavy rain starting Monday night and lasting into Wednesday may drive some rivers in the region above flood stage, according to the National Weather Service.

During a 48-hour period, 4 to 7 inches of rain are expected in the Cascades and 5 to 8 inches of rain are expected in the Olympic Mountains, with snow levels above 7,000 feet as the heaviest rain falls.

“These rainfall amounts — if they occur — could result in some flooding on the more flood-prone rivers flowing out of the Olympics and Cascades,” the Weather Service wrote in a bulletin.

Those high snow levels will cause the rain to melt snow that has fallen and stuck around in the mountain ranges’ foothills, putting all that water into the region’s rivers, now running low.

The rivers in the region most likely to be affected are the Skokomish and Chehalis, Weather Service meteorologist Johnny Burg said.

The Weather Service advises people who live in flood-prone areas to monitor the forecasts and be prepared for flood watches and warnings.

In Tacoma, temperatures are expected to be in the mid-40s Monday before half an inch of rain or more arrives in the evening. Highs should be in the low 50s Tuesday and Wednesday, with an inch or more of rain each day, with lows in the low 40s.

Similar conditions are expected in Olympia, though winds and rainfall should be stronger.

“We have the jet stream right over us,” Burg said. “That’s why we’re going to get that deeper precipitation. That kind of steers the precipitation in our direction.”

For much of the last month, the jet stream has gone over Oregon as high pressure from Canada has persisted over Washington, Burg said.

Showers and high temperatures in the 40s should carry through the rest of the week throughout the South Sound.