Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 248 PM EST Tue Jan 10 2023 Valid 00Z Wed Jan 11 2023 - 00Z Fri Jan 13 2023 ...High Impact Heavy Precipitation will continue across much of California through tonight... ...Heavy mountain snow will continue across the West through tonight... ...Next Atmospheric River arrives Wednesday and will impact northern California and the Pacific Northwest... ...Isolated to scattered severe thunderstorms possible in the Southeast on Thursday... Back-to-back atmospheric river events continue to hammer California and pose flooding threats. Radar showed widespread moderate to heavy rainfall across much of California this afternoon. The system currently producing precipitation is forecast to move east across the Intermountain West tonight and emerge into the Plains on Wednesday. Heavy precipitation will continue for much of California through tonight, and scattered to widespread instances of flash flooding will be possible, especially near steep terrain and burn scars. There is a Slight Risk of Excessive Rainfall (level 2/4) in effect for much of the coast and Central Valley with an embedded Moderate Risk area (level 3/4) over part of southern California for sensitive areas along the upslope portions of the Transverse Ranges. Heavy snow will also continue through tonight at high elevations across the West, and some locations could receive an addition few feet of snow. There will be a brief break in the rainfall in the West late tonight before the next atmospheric river arrives Wednesday. Moisture will stream ahead of a large cyclone in the eastern Pacific Ocean, which will produce heavy precipitation in northern California. As the system slowly approaches the West Coast, precipitation will spread north into the Pacific Northwest Wednesday night and continue through the end of the work week. Soils in California are saturated from above average rainfall over the past few weeks, which means it won't take much additional rainfall to trigger flooding. There is a Slight Risk of Excessive Rainfall (level 2/4) in effect for much of the northern California coast for Wednesday, and scattered instances of flash flooding will be possible. Soils in the Pacific Northwest are not nearly as saturated as the soils in California, so flooding concerns in the Pacific Northwest will not be as high as in California. The one benefit of above normal rainfall in California is the relief from persistent drought that has been plaguing the state for quite some time. For the eastern half of the CONUS, the next storm system will be the one traversing the Intermountain West tonight and emerging into the Plains on Wednesday. This system will move across the central and southern Plains through Wednesday evening, towards the Middle Mississippi Valley Wednesday night into Thursday, and then push into the Northeast Thursday night into Friday. Widespread showers and thunderstorms are expected in the eastern third of the nation on Thursday, with isolated to scattered severe storms possible in the lower Mississippi Valley, Tennessee and Ohio Valleys, and Southeast. The Storm Prediction Center has issued a Slight Risk of Severe Thunderstorms (level 2/5) for parts of the Southeast for Thursday. Damaging winds should be the main severe storm threat, but a brief tornado or two may also be possible. On the northern side of the system, snow and wintry mixed precipitation will be possible, mainly in the Upper Midwest and Great Lakes region. Dolan Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php