ESFPDT Synopsis: Rain and high mountain snow from and multiple systems this weekend and early next week will lead to rising water levels on area streams and rivers. Rainfall amounts of 2 to 5 inches are expected in the Cascades and 1 to 3 inches in the eastern Oregon mountains. In addition, temperatures will be rising to the 40s and lower 50s in the mountains which will lead to snow melt adding even more water to area rivers and streams. The National Water Model is highlighting high water on numerous smaller streams and creeks, but streamflow amounts are generally only slightly higher than high water thresholds. What: Precipitation fed by an atmospheric river and snow melt due to warmer temperatures this weekend into early next week will lead to rises on area creeks, streams and rivers. Rivers are low enough so that most rivers will remain below bankfull. However, the Walla Walla River at Touchet and the Naches River at Cliffdell are expected to exceed bankfull late Sunday night before receding Monday and Tuesday. Another concern will be rapid rises on smaller streams and creeks due to heavier downpours and snowmelt. This could lead to debris flows on recent burn scars and over steep terrain. The Walla Walla River at Touchet has a 44 percent chance of exceeding bankfull but less than a 5 percent chance of reaching minor flood stage. It is expected to reach bankfull late Sunday evening and remain there through Tuesday morning. The Naches River at Cliffdell has a 29 percent chance of exceeding bankfull but less than a 5 percent chance of reaching minor flood stage. It is expected to reach bankfull late Sunday evening and remain there until dropping below bankfull Monday afternoon. The Klickitat River at Pitt is forecast remain below bankfull, but model probabilities give it a 13 percent chance of rising above bankfull and a 9 percent chance of reaching minor flood stage. All other river forecast points have a less than a 10 percent chance of exceeding bankfull. When: Rain will begin tonight and continue through Monday with the heaviest rain expected Saturday night and Sunday. Where: The Upper and Lower East Slopes of the Washington and Oregon Cascades, The Simcoe Highlands, The Northern and Southern Blue Mountains, The Blue Mountain Foothills of Washington and Oregon, Wallowa County and the Grande Ronde Valley. This Hydrologic Outlook will be updated as needed due to changing conditions.
