This report is a compilation of precipitation data from U.S. Geological Survey telemetered "Early Flood Warning" sites near Mount St. Helens, Washington, and from telemetered hydrologic data sites in the Toutle River and Muddy River basins for the years 1981-86. It also includes precipitation data for 1981-86 from non-telemetered recording rain gages established near the debris-avalanche blockages of Spirit Lake, Coldwater Lake, and Castle Lake. Daily values (midnight to midnight) are listed by station and calendar year for 32 sites. Hourly data, where available, are presented for the storm that generated the highest peak discharge in the North Fork Toutle River each water year. Instrumentation includes 25 tipping-bucket, and 7 weighing-bucket rain gages all without windshields. The seven sites with weighing-bucket gages were the only U.S. Geological Survey sites at which snowfall was measured. Additional snowfall measurements for the same time period in the Mount St. Helens area were collected by the National Weather Service, the U.S. Soil Conservation Service, and the U.S. Army Corps of Engineers and also are presented in this report.Terms defined in "Explanation of Terms" are in bold print where first used in the main body of this report. * Outside of the Mount St. Helen's study area; not shown on plate 1.[Values in inches. Because SNOTEL stations were not in existence for the entire 25-year period of the data summary, the Soil Conservation Service computed averages by correlation with long-term record sites] Station
, North west Oregon experienced ing in recorded history. Heavy, warm rain fell on above average snowpack in the Cascade Range of the Wil lamette River Basin, resulting in 50-to 100-year flood events in many area rivers. The North Santiam River at Mehama crested at nearly 2½ feet above flood stage on 1996. Although the water level returned to normal within a few weeks, the water months to come.
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