Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 304 PM EST Thu Nov 22 2018 Valid 00Z Fri Nov 23 2018 - 00Z Sun Nov 25 2018 ...Unsettled weather continues for the West with heavy snow in higher elevations and heavy rain along the West Coast, with flash flooding and debris flows possible over burn scars... ...Widespread rain is expected in the Mississippi Valley on Friday, spreading to the East on Saturday... ...Light frozen precipitation possible in the Southern and Central Appalachians Friday night into Saturday morning... ...Record lows will be widespread across the Northeast and northern Mid-Atlantic region Friday morning... As a series of surface low pressure systems and fronts come through the western U.S. along with upper-level disturbances, heavy precipitation is expected to continue. In the lower elevations of the Pacific Northwest and Northern California, rain is likely, and there is a Marginal Risk of excessive rainfall/flash flooding in parts of Northern California and southwestern Oregon. There are embedded Slight Risks of excessive rainfall over burn scars, over which rain runs off easily. Debris flows are also possible in those areas. By Saturday, a break in the heavy rain is expected, but showers could continue. Snowfall-wise, 1 to 2 feet of snow is expected in the Northern and Central Rockies, as well as the Wasatch and Bitterroot Range through the end of the week. Precipitation will form by Friday morning ahead of a developing cold front in the central U.S., and as an upper-level trough pushes the front eastward, spread into the eastern U.S. by Saturday. The precipitation will be mostly rain, except for snow in the Upper Mississippi Valley on Friday evening into Saturday, and also into the Southern and Central Appalachians. There, light snow and freezing rain are forecast on Friday night into Saturday morning, which could cause slick travel conditions temporarily. Rain will move from the Mississippi Valley on Friday into the Tennessee and Ohio Valleys and Southeast on Friday night. Generally less than an inch of rain is forecast in those areas. On Saturday, rain will spread into the Mid-Atlantic states, and above an inch of total precipitation could fall (rain combined with the liquid equivalent of the light freezing rain and snow) in the Appalachians. A low pressure system will track eastward along the Gulf Coast through the end of the week, leading to scattered showers and thunderstorms across the Gulf Coast states on Friday. By Saturday, the Western and Central Gulf Coast will dry out as the cold front passes, with showers remaining in Florida. The cold temperatures felt this Thanksgiving in the northern Mid-Atlantic and Northeast will continue into Friday morning. Low temperatures are expected to remain 15 to 30 degrees below average there, which will lead to widespread record lows. Temperatures will slowly warm over the next couple of days, but remain below average through the end of the week there. Meanwhile, temperatures of 5 to 15 degrees above average are forecast for the central U.S. Tate Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php