UPDATE SATURDAY MORNING:
The King County Flood Warning Center closed Saturday morning as rivers in the county returned to stable levels and the immediate threat of flooding passed, according to King County. However, the threat could return when another wet weather system moves into Western Washington late tonight or early Sunday.
UPDATE FRIDAY NIGHT: The following is a press release from King County Friday night:
The King County Flood Warning Center, which has been monitoring rain-swollen rivers since midday on Jan. 13, has issued a Phase II flood alert level for the Green River. Only minor flooding could occur as a result of controlled increased flows on the Green River, and only in areas without river levees upstream of Auburn.
Meanwhile, the Snoqualmie and Tolt rivers remain at Phase II flood alert levels, with very minor flooding of low-lying areas noted.
Flows on the Green River are expected to reach or exceed 7,000 cubic feet per second (CFS) late Friday evening, Jan. 14, or early Saturday morning, Jan. 15, as part of planned releases from Howard Hanson Dam, the U.S. Army Corps of Engineers’ flood-control dam in the upper Green River watershed. Releasing water now provides the Corps with additional flood-storage capacity for anticipated heavy rainfall later this weekend.
HERE IS THE EARLIER VERSION OF THE STORY
Unseasonably warm weather and heavy rainfall will continue in Renton and elsewhere in Western Washington through the weekend.
The temperature at about 4 p.m. Friday was 56 degrees at Renton Municipal Airport.
The National Weather Service has issued a flood watch through Sunday for several counties, including King. However, the Cedar and Green rivers are expected to remain below flood stage, even minor flooding.
In the Snoqualmie Valley, however, minor flooding on the Snoqualmie and Tolt rivers has already prompted some road closures, according to King County. No road closures are reported in the unincorporated areas along the Cedar near Renton.
Up to additional four inches of rain could fall in the lowlands of Western Washington, according to the weather service. That amount of rain could increase the chance for landslides, but so far no landslides have been reported in the Renton area.
Sunday, snow will only fall above 7,000 feet in the Cascades.
In a press release Friday, the U.S. Army Corps of Engineers indicated it does not expect the amount of precipitation in the basins of the Green and White rivers to challenge the operations of the dams controlling the two rivers, including Howard Hanson on the Green.
The corps keeps the reservoir behind Howard Hanson Dam until storage is required for flood-risk management. This weekend’s rain systems may require some storage at both dams. The Mud Mountain Dam is used for storage on the White River.
Potential flows of 9,000 cubic feet per second as measured at the Auburn gage are possible. Such flows trigger a flood warning from the National Weather Service due to flooding concerns in the Middle Green River, according to the corps. However, those flows do not present flooding concerns for areas downstream, including Auburn, Kent, Tukwila or Renton.
