Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 403 PM EDT Mon Mar 19 2018 Valid 00Z Tue Mar 20 2018 - 00Z Thu Mar 22 2018 ...Severe thunderstorms expected from the eastern Tennessee Valley to parts of the Southeast later today and Tuesday... ...Accumulating snow expected from parts of the Ohio valley, central/southern Appalachians into the Mid-Atlantic and southern New England... ...Coastal storm to potentially bring heavy snow and gusty winds to portions of the Northeast Coast on Wednesday... ...Heavy rain, possible flash flooding for portions of southern California... Severe weather is in the forecast for portions of the Southeast this evening as warm and humid air lift northward into the region ahead of a low pressure system, which was moving through the lower Mississippi valley Monday afternoon. The greatest threat for severe storms will be in the vicinity of northern Alabama as highlighted by the Storm Prediction Center, with the focus shifting to the Southeast's coastline for Tuesday ahead of an advancing cold front. A complex evolution of fronts and surface lows will evolve through Tuesday, as moisture moves northeastward into the eastern U.S. While temperatures are fairly mild as of Monday afternoon from the Ohio valley into the Mid-Atlantic region, colder temperatures to the north are expected to filter down into the region, allowing a changeover from rain to a wintry mix early Tuesday morning for portions of the Ohio valley and northern Mid-Atlantic region. Low pressure is expected to consolidate off of the Mid-Atlantic coast Tuesday night into Wednesday, allowing for precipitation to organize west of the low center along with increasing winds. Given colder air will continue to filter southward over the next 24-48 hours, much of the precipitation is expected to be snow, as far south as portions of southern Virginia into central North Carolina. Given temperatures at the surface will only be marginally supportive of snow to the east of the Piedmont, especially during the daytime hours, accumulations may be limited to grassy surfaces for these locations. The greater potential for heavier snowfall accumulations will be across the higher elevations of the Appalachians and into portions of New Jersey, the New York City metropolitan region and southern New England Tuesday night into Wednesday. Elsewhere, a significant source of Pacific moisture is forecast to aim into southern California starting late Tuesday morning. Relatively slow movement of this moisture axis is expected to lead to heavy rainfall totals across lower elevations along the California coast and inland through Thursday. Given recent burn scars in the vicinity of the Los Angeles area, flash flooding will be a concern. Heavy rain and possible flooding will also extend downstream into the Sierra Nevada below roughly 8000 feet elevation, with locations higher than 8000 feet likely to receive very heavy snow. Otto Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php