A hydrologic outlook was issued on Sunday at 5:23 p.m. The alert is for Coastal Del Norte, Del Norte Interior, Northern Humboldt Coast, Southwestern Humboldt, Northern Humboldt Interior, Southern Humboldt Interior, Southern Trinity, Mendocino Coast, Northwestern Mendocino Interior, Northeastern Mendocino Interior, Southwestern Mendocino Interior, Southeastern Mendocino Interior and Southern Lake County as well as Lake County.
A strong and prolonged atmospheric river will impact NW California mid to late week. Moderate to locally heavy rainfall will bring the potential for rapid rises on rivers, streams and creeks across the region. Rain will be heaviest on Wednesday with 2 to 4 inches of rain. High peaks in the King Range could see 6 to 9 inches of rain over 24 hours. Most models show more moderate but persistent rain continuing Thursday through next Saturday with most likely rainfall of 1 to 3 inches each day. Total Storm amounts could easily reach between 6 and 14 inches over 4 days, with up to 21 inches for the King Range for the greatest risk is for Humboldt and Del Norte counties where soils are already near saturation. Significant rain are also expected for Mendocino and Lake counties, though generally drier soils will reduce the flood risk. Much of the precipitation in Trinity County will likely fall as snow with snow levels in the eastern half of the county as low as 2500 feet greatest risk of heavy rain during the day on Wednesday. More moderate but prolonged rain Thursday through Saturday. The forecast is more uncertain further out. Long range models show the potential for rain to continue into Thanksgiving Week.
"Such rain amounts will greatly increase the risk of flooding, especially for the northern half of the area where soils have already been saturated by previous rain events. Expect flooding on in low-lying areas, areas with poor drainage, and increased risk of debris on roadways. Rivers, streams and creeks will rapidly rise. The Eel River is around 20 percent chance of exceeding flood stage Thursday evening. The Mad River and the Russian River are showing 5 to 10 percent of reaching flood stage," adds the NWS.
Source: The National Weather Service