Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 350 AM EST Thu Dec 05 2013 Valid 12Z Thu Dec 05 2013 - 12Z Sat Dec 07 2013 ...Heavy rain possible from parts of the Central Appalachians to parts of the Lower Mississippi Valley... ...Heavy snow possible from parts of the Ohio Valley to Middle Mississippi Valley... ...Temperatures will be 10 to 30 degrees below average over the Plains into parts of the Mississippi Valley... A strong front extending from the Great Lakes to the Southern Plains will move eastward to the Mid-Atlantic to the Central Gulf Coast while moving off the Northeast Coast and the Western Gulf Coast by Friday evening. Moisture from the Gulf of Mexico will overrun the boundary producing showers and thunderstorms along and ahead of the front from the Western Gulf Coast to the Tennessee/Western Ohio Valleys moving to the Eastern Gulf Coast/Southern Mid-Atlantic by Friday. Rain will develop north of the front from parts of the Southern Plains to parts of New England by Thursday evening. The rain will increase in intensity to light to moderate rain over the Ohio Valley to parts of the Tennessee/Lower Mississippi Valleys on Friday morning, moving to Southern New England/Central Gulf Coast by Friday evening. Mainly sleet will develop slightly farther north of the front, on Thursday afternoon, from parts of the Southern Plains into the Lower Mississippi Valley. The sleet will expand into parts of the Western Ohio Valley and the Middle Mississippi Valley by Thursday evening, ending over the region during the morning hours on Friday. In addition, snow will develop over parts of the Southern Rockies that will expand into parts of the Southern High Plains by Thursday evening. The snow will continue to expand into parts of the Ohio Valley by Friday. Rain will also develop over parts of the Southern High Plains into parts of the Southwest, ending on Thursday evening. Meanwhile, upper-level energy along the British Columbia Coast will move southward along the Northwest Coast Thursday afternoon into Friday. The system will produce snow over parts of the Pacific Northwest into interior parts of Northern California, with rain over the Northern California Coastal area on Friday. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php