![]() During November, prior to the flooding, Oregon had steady but heavier-than-normal rainfall, with heavier snow in the mountains. The floods followed a 20-year-long drought. With the right dynamics in place to provide lift, an atmospheric river can produce astonishing amounts of precipitation, especially if it stalls over an area for any length of time. Īn atmospheric river is a wind-borne, deep layer of water vapor with origins in the tropics, extending from the surface to high altitudes, often above 10,000 feet, and concentrated into a relatively narrow band, typically about 400 to 600 kilometres (250 to 370 mi) wide, usually running ahead of a frontal boundary, or merging into it. In 2012, hydrologists and meteorologists concluded that the precipitation was likely caused by a series of atmospheric rivers that hit the Western United States along the entire West Coast, from Oregon to Southern California. The weather pattern that caused this flood was not from an El Niño-type event, and from the existing Army and private weather records, it has been determined that the polar jet stream was to the north, as the Pacific Northwest experienced a mild rainy pattern for the first half of December 1861. At least 4,000 people were estimated to have been killed in the floods in California, which was roughly 1% of the state population at the time. The governor, state legislature, and state employees were not paid for a year and a half. The storms caused approximately $100 million (1861 USD) in damage, approximately equal to $3.117 billion (2021 USD). It has been described as the worst disaster ever to strike California. The resulting snow-melt flooded valleys, inundated or swept away towns, mills, dams, flumes, houses, fences, and domestic animals, and ruined fields. The event was capped by a warm intense storm that melted the high snow load. Immense snowfalls in the mountains of far western North America caused more flooding in Idaho, Arizona, New Mexico, as well as in Baja California and Sonora, Mexico the following spring and summer, as the snow melted. The event dumped an equivalent of 10 feet (3.0 m) of water in California, in the form of rain and snow, over a period of 43 days. This was followed by a record amount of rain from January 9–12, and contributed to a flood that extended from the Columbia River southward in western Oregon, and through California to San Diego, and extended as far inland as Idaho in the Washington Territory, Nevada and Utah in the Utah Territory, and Arizona in the western New Mexico Territory. It was preceded by weeks of continuous rains and snows that began in Oregon in November 1861 and continued into January 1862. The Great Flood of 1862 was the largest flood in the recorded history of California, Oregon, and Nevada, inundating the western United States and portions of British Columbia and Mexico. Washington, Oregon, Nevada, California, Idaho, Arizona, New Mexico, Utah, Baja California, Sonora, Mexico The Snow Survey and Water Supply Forecasting Program is actively working on a correction technique for this issue.Lithograph of K Street in the city of Sacramento, California, during the Great Flood of 1862 It has been determined that the this algorithm has resulted in a data bias. calculate temperature from sensor output voltage using a linear least-squares regression algorithm. In addition, the extended range air temperature sensors used at SNOTEL sites in the continental U.S. HOURLY DATA, OTHER THAN THE MIDNIGHT VALUES, SHOULD BE CONSIDERED PROVISIONAL AND MAY HAVE SIGNIFICANT ERRORS. The only data that are reviewed at the hourly time step are the soil moisture and soil temperature values. * SNOTEL Data Quality: Snow Survey staff review and quality-control only the daily (midnight) readings from SNOTEL sites. NRCS Nevada / Eastern Sierra Snow Course Measurement Schedule US Drought Monitor: Nevada | West | Info.Other Forecast Products - Tables, Maps, Unofficial Daily Forecasts Visual representation of streamflow forecast range showing the five exceedance probabilities compared to 30-year normals. Water Year Precipitation Percent of Median.Data types include SNOTEL, snow course, streamflow, reservoir storage, and streamflow forecasts and more. Daily Maps: Snow | Water Year Precip | Monthly PrecipĬharts for snowpack, precipitation, air temp and soil moistureĭisplays both current and historic data in an easy-to-use, visual interface.Month-to-date Precipitation as Percent of Monthly Median.Snow and Precipitation Percent of Median.Applications of snow survey products include water supply management, flood control, climate modeling, recreation, and conservation planning. The Nevada NRCS Snow Survey and Water Supply Forecasting Program provides mountain snowpack data and streamflow forecasts for the state of Nevada, as well as, the Eastern Sierra Nevada. Welcome to the Nevada Snow Survey Homepage
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