By late Friday afternoon, Winter Storm Warnings expanded south to the Houston area and eastward to the Atlantic Seaboard. Initial focus zones for severe icing are East Texas, the northern 2/3 of Louisiana, southern Arkansas, and northern Mississippi plus northern Georgia and the western half of South Carolina.

The new concern is a larger exposure of significant ice accretion, especially northward through the Mid-Atlantic region to the south and southeast coast of New England. Already, widespread power loss and impossible travel due to a major ice accretion is forecast for the Mid-south U.S. plus the Carolinas. However, the ice accretion forecast trend leaves Virgina in a similar risk and Washington/Baltimore/Philadelphia could be added.

Along an arctic air boundary, a major ice storm develops Friday across the southern Great Plains extending to the Mid-south U.S. and quickly eastward Saturday into the Carolinas. The Interior Southeast is also affected. Ice accretion of 0.5 to 1.0 inches is possible in this stretch which will cause widespread power outages. Heavy snows extend from the southern Great Plains to the Tennessee Valley. Jackpot snows (18-21 inches) are forecast for Virginia. Southeast New England is added to the heavy snow risk.

A major icing event is forecast for parts of north-central Texas, northern Louisiana/southern Arkansas and eastward across northern Mississippi to South Carolina for late this week and weekend. Dallas and Atlanta are in the major icing threat zone.

The next major issue for the U.S. is an arctic outbreak scheduled to arrive across the northern Great Plains Wednesday night, according to the just arrived 12Z GFS. On Thursday, the arctic boundary shifts southward reaching Des Moines to Chicago early evening, accelerating southward Thursday night to northwest Texas Friday morning and eastward across Arkansas to the Ohio Valley. By Friday afternoon, the arctic air is filtering through New England and into the northern Mid-Atlantic region southwestward to northern Texas.