Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 404 AM EDT Sun Mar 12 2023 Valid 12Z Sun Mar 12 2023 - 12Z Tue Mar 14 2023 ...There is a Moderate Risk of excessive rainfall over parts of California... ...Heavy snow over parts of the Upper Mississippi Valley on Sunday and the Northeast on Monday; Pockets of rain/freezing rain over parts of the Central Appalachians... ...There is a Slight Risk of severe thunderstorms over parts of the Lower Mississippi and Southeast... A storm over the Upper Mississippi Valley will move eastward to just off Long Island by Tuesday morning. The system will produce moderate to heavy snow that will continue across portions of the Upper Midwest Sunday and Sunday night, producing an additional 4-6 inches of snow across northeast Minnesota near Lake Superior and across much of northern to east-central Wisconsin. The snow will result in reduced visibility and hazardous driving conditions. The storm will also produce blizzard conditions over parts of the Upper Midwest through early Sunday afternoon. This system will reach the Mid-Atlantic coast Monday night, leading to a rapidly strengthening coastal low pressure. Confidence is increasing that a major norâ€easter will affect parts of the Northeast Monday Night - Wednesday. Heavy snow rates (up to 2 inches per hour possible) and strong winds from this norâ€easter will likely produce dangerous to near impossible travel. The heavy-wet nature of the snow could result in scattered to widespread power outages and tree damage. Confidence is increasing that some interior, higher elevation areas across the interior Northeast will receive greater than 12 inches of snow. In addition, the system may produce localized higher snowfall amounts for portions of the Catskills in New York, Berkshires in western Massachusetts, and southern Green Mountains in Vermont. Widespread minor coastal flooding may be possible Monday Night through Wednesday as the low pressure deepens off the coast of New England. As the precipitation moves into the Central Appalachians, pockets of rain/freezing rain will develop on Sunday. The combination of snow and ice may cause hazardous road conditions over parts of the Central Appalachians. In the meantime, a second storm over the Tennessee Valley will move eastward to off the southern Mid-Atlantic Coast by Monday. The system will produce showers and severe thunderstorms as the associated front moves across the Lower Mississippi/Tennessee Valleys. Therefore, the SPC has issued a Slight Risk of severe thunderstorms over parts of the Lower Mississippi and Southeast through Monday morning. The hazards associated with these thunderstorms are frequent lightning, severe thunderstorm wind gusts, hail, and a few tornadoes. Additionally, the storms will create moderate to heavy rain. Therefore, the WPC has issued a Marginal Risk of excessive rainfall over parts of the Lower Mississippi Valley into the Southeast through Monday morning. The associated heavy rain will create localized areas of flash flooding, affecting areas that experience rapid runoff with heavy rain. On Monday, the threat of severe thunderstorms decreases slightly, while the threat of excessive rainfall ends. Therefore, the SPC has issued a Marginal Risk of strong to severe thunderstorms over parts of the Florida Peninsula from Monday into Tuesday morning. The hazards associated with these thunderstorms are frequent lightning, severe thunderstorm wind gusts, hail, and a minimal threat of tornadoes. Meanwhile, onshore flow will produce coastal rain and highest elevation snow over parts of California and the Pacific Northwest through Tuesday. The system will create rain in low elevations and foothills, and snow at high elevations, from Northern to Central California, as well as northwest Nevada, and Oregon on Sunday. Furthermore, rain and snow to intensify Monday into Tuesday. Considerable flooding impacts below 5000-foot elevation along the central California coast, San Joaquin Valley, Sacramento Valley, and southern Sierra Nevada foothills into Tuesday. Additionally, heavy rain and snowmelt may lead to renewed (more widespread) flooding from Monday to Tuesday, particularly in low elevations and shallow and warming snowpack areas. Creeks and streams will continue to be vulnerable to flooding from additional rain and snowmelt. As a result of the heavy rain, the WPC has issued a Slight Risk of excessive rainfall with these thunderstorms. The associated heavy rain will create mainly localized areas of flash flooding, with urban areas, roads, small streams, and burn scars the most vulnerable. On Monday, the threat of excessive rainfall increases. Therefore, the WPC has issued a Moderate Risk of excessive rainfall over parts of Northern/Central California and southwestern Oregon from Monday into Tuesday morning. The associated heavy rain will create numerous areas of flash flooding. Furthermore, many streams may flood, potentially affecting larger rivers. Moreover, on Monday, a front will move onshore over the Pacific Northwest and inland to the Northern Rockies by Tuesday. As the front passes, the snow levels will low over the Northwest and snow will move into parts of the Northern Intermountain Region and parts of the Central Rockies overnight Monday into Tuesday. Ziegenfelder Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php