From the NWS Weather Prediction Center in College Park, Maryland, at 130AM EST on Fri Dec 7 2018
Valid 12Z Fri Dec 7 2018 - 12Z Sun Dec 9 2018
Winter storm to bring ice and snow from the southern plains to the Appalachians, and heavy rain from eastern Texas to Georgia... A strong storm system crossing the Desert Southwest early Friday morning will take a southerly track across the southern plains to the Deep South and then the southeast U.S. coast through the weekend. Snow and freezing rain is forecast to overspread eastern New Mexico and the Texas/Oklahoma panhandles by late Friday, and continuing into early Saturday. The greatest snowfall accumulations through early Saturday are expected across the southern High Plains from eastern New Mexico and across parts of the Texas Panhandle, with amounts on the order of 3 to 6 inches and locally higher. In addition, ice accretion of about a tenth of an inch, perhaps higher, will be possible on the southern edge of the heavier snow band, roughly from Lubbock to Oklahoma City.
In the warm sector of the surface low, heavy rain is forecast across southeast Texas in response to a deep surge of moisture from the Gulf of Mexico. The Weather Prediction Center currently has a Moderate Risk of excessive rainfall for Friday and Friday night for much of southeast Texas, with several inches of rainfall expected. The rainfall rates are expected to be high at times, increasing the threat of flooding. Flash flood watches are also in effect for this region.
A slight risk of excessive rainfall exists through Saturday night for the central Gulf Coast region as heavy bands of showers and thunderstorms develop in conjunction with the surface low and a deep moisture surge ahead of it. As the surface low tracks eastward roughly along the Gulf Coast through late Sunday, a swath of accumulating snow and ice is expected to extend from eastern Oklahoma to the southern Appalachians.
Winter storm watches are now in effect from the Texas Panhandle to the Ozarks of northern Arkansas, and also for the southern Appalachians and adjacent Piedmont region. Travel will likely be severely affected across much of these areas, and some power outages are also possible. Elsewhere across the nation, some lake effect snow is likely across parts of Michigan and New York for Friday and Saturday as cold northwesterly flow crosses the warmer lake waters. Showers and mountain snow returns to western Washington and Oregon on Saturday as a cold front approaches from the eastern Pacific. Colder than normal temperatures are expected to persist across much of the central and northern U.S. through Saturday with a large Canadian surface high in place.