Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 249 AM EST Sun Nov 10 2024 Valid 12Z Sun Nov 10 2024 - 12Z Tue Nov 12 2024 ...Wet Sunday for much of the eastern U.S., including beneficial rainfall for the Northeast... ...An Atmospheric River will bring heavy coastal rain and high elevation snowfall to portions of the Pacific Northwest beginning Sunday night... ...Above average temperatures will continue into next week for most of the country... A broad area of showers and thunderstorms ahead of a low pressure system/arcing frontal boundary through the Midwest south into the Mississippi Valley early Sunday morning will continue eastward through the day, bringing an expanding area of moderate to heavy rainfall over the eastern U.S. The front will push eastward through the Ohio Valley/interior Northeast and into New England and the Mid-Atlantic by Sunday evening, bringing beneficial rainfall following many weeks of little to no precipitation. Further south, the front will make slower progress and keep additional storm chances focused over the Tennessee and Lower Mississippi Valleys following heavy rain Saturday. Moisture streaming northward from the Gulf, influenced in part by Tropical Storm Rafael, will lead to some locally heavy downpours, with isolated flash flooding possible. A localized Slight Risk of Excessive Rainfall (level 2/4) is in place over central Louisiana where continued rainfall early Sunday over very saturated grounds/ongoing flooding may lead to a few more scattered instances of flash flooding. An additional area of showers and thunderstorms is expected for portions of the coastal Carolinas/Georgia and into Florida in vicinity of a wavy frontal boundary. Most of the rainfall should come to an end by early Monday as the front begins to clear the coast over the Northeast and moisture return decreases to the south, though some lingering showers will remain possible for the interior Northeast as a secondary cold front passes through. Some light to moderate lower elevation rain showers and higher elevation snows will continue over portions of the Pacific Northwest/northern Rockies through Sunday afternoon as a wavy frontal boundary lingers in the region. Then, a stronger Pacific storm system/Atmospheric River will approach the Pacific Northwest Sunday evening bringing moderate to heavy coastal rains by Sunday night. This system will continue inland into the day Monday with an expanding area of precipitation across the Pacific Northwest, northern Great Basin/Rockies, and northern/central California. Favorable upslope areas along the coastal mountain ranges may see 2-3" of rain, with some potentially moderate to heavy accumulating snows for higher elevations of the Cascades, Sierra Nevada, and northern Rockies. Another system just beyond the current forecast period looks to bring another round of heavy rain and mountain snows mid-week. Most areas of the country will continue to see temperatures 5-15 degrees above average over the next couple of days. Forecast highs Sunday range from the 50s for the Pacific Northwest, Great Basin, northern Rockies/Plains, Great Lakes, and New England; the 60s in California, central Plains, Ohio Valley, and Mid-Atlantic; and the 70s and 80s for the Desert Southwest, Texas, Lower Mississippi Valley, and the Gulf Coast. Much of the East Coast will see even warmer highs on Monday as rain clears out, with highs rising into the 60s for coastal New England and the 70s for the Mid-Atlantic, Carolinas, and Georgia. One region that will remain colder will be portions of the central/southern Rockies and High Plains where grounds remain snow covered following this past Friday's historic storm, with highs mainly in the 40s to low 50s. Putnam Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php