Flood — Walla Walla, Washington

2020-02-06 to 2020-02-09 · near Touchet, Walla Walla, Washington

Event narrative

Record high water levels were seen on Upper Mill Creek with extensive damage along upper Mill Creek to homes as well as roads and bridges. A number of residents had to be evacuated via helicopter or 4 wheeler. There was minimal damage along Mill Creek through Walla Walla as water was diverted through the Mill Creek Flood Project. Downstream of Walla Walla, there was damaging flooding in College Place with a bridge being washed out near Wallula Road. In Waitsburg, flood waters from both the Touchet River and Coppei Creek inundated the town as levees were damaged. 60 homes were damaged as well as numerous roads and bridges. Damage countywide is estimated at 8.77 million dollars. Walla Walla nr Touchet ' Flood stage is 13.0 feet. The river rose above flood stage on February 6th at 730 pm, crested at 20.26 feet on February 7th at 445 pm, then fell below flood stage on February 9, 7 am. Major flooding occurred along the Walla Walla River from the headwaters through Milton Freewater to the confluence with the Columbia River. There was extensive damage to roads, bridges and damage to levees through Milton- Freewater. There was widespread flooding of pastures from Milton Freewater to the mouth, with portions of Highway 12 covered by water.

Wider weather episode

Heavy snow on February 4-5, 2020 was followed by a period of heavy rain, February 5-7. Snow levels rose to near 5000 feet. The heavy rain and snow melt lead to moderate flooding and several landslides along the East Slopes of the Washington Cascades. There was record flooding on several rivers, including the Umatilla, Walla Walla and Touchet rivers with widespread flooding of numerous other creeks and streams and rivers across Umatilla, Union and Wallowa Counties of Oregon and Walla Walla and Columbia Counties of Washington. Initial Weather Conditions February 1, 2020, snowpack across along the East Slopes of the Washington Cascades ranged from 80 to 100 percent of normal. Across the northern Blue Mountains of Oregon and northern Blue mountains of Washington the snowpack was near normal. A weather system brought heavy snow to this region on February 4th and the first part of the day on February 5th with snow amounts from around 10 to 20 inches for locations between 2000 to 4000 feet. During the afternoon of the 5th, snow changed to rain at elevations below 5000 feet. Selected locations snow amounts for February 4-5, include 8 inches at 2.6 miles SSE of Snoqualmie Pass, 7 inches at Cle Elum, 2 inches at Easton, 12.5 inches at Ski Blue Wood and 2 inches at Dayton in Columbia County. For Oregon, snow amounts include, La Grande 7-10 inches, Summerville 10 inches, La Grande, 5 Miles NNE- 17.5 inches, Meacham 13 inches, Elgin 9.8 N 8 inches, Joseph 6 inches and Wallowa 8 inches. The rain continued over through February 6 and 7th. Precipitation amounts in the form of rain at the headwaters of the rivers, ranged from 3 to 5 inches. Rain amounts for the 48 hours ending on the morning of February 8th, for selected locations include 6.31 inches at 2.6 miles SSE of Snoqualmie Pass, 3.27 inches at Easton, 5.83 inches near Lake Cle Elum and 2.17 inches at 8.7 miles NE Dayton. Snotel sites reported 2 day precipitation amounts of 6.3 inches at Touchet #2 in the Columbia County. There was 1.98 inches over 72 hours at 1.1 NE Walla Walla. In Oregon, rain amounts for the 48 hours ending on the morning of February 8th for selected locations include: from Coop Observer, Emigrant Springs ' 2.82 inches, Union 1.01 inches , Cove- 2.48 inches, La Grande - 2.50 inches, Lostine ' 1.39 inches. From CoCoRahs and other public weather spotters, 9.8 N Elgin ' 5.45 inches, La Grande- 3.02 inches and Wallowa 2.66 inches. Snotel sites reported 2 day precipitation amounts of 5.9 inches at High Ridge, 3.0 inches at Moss Springs, 1.6 inches at Milkshake. In addition, the snowpack from the preceding day was melted, contributing to the runoff. Observations show 5 to 7 inches of snow melted from February 5th to February 6th at Easton and Cle Elum. Home owners in the Lake Cle Elum area noted a loss of 3 to 5 feet of snow An observer located 5 miles north of La Grande reported 17.5 inches of snow fell on February 4-5 and then by the morning of February 6th, the snow depth had decreased to around 8 inches and was depleted during the day on the 6th. Satellite snowpack images show 1-3 inches of snow water equivalent (or water held in the snowpack) melted out along both the east and west sides of the northern Blue Mountains in Oregon and around the foothills of the Grande Ronde Valley generally between 2000 to 4000 feet.

View location on OpenStreetMap → (46.0300, -118.6700)

Source: NOAA Storm Events Database, event_id 871995. Narrative written by the NWS forecast office that issued the report.