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.

The ECM 30-day Madden Julian oscillation forecast indicates a phase_6 to phase_7 shift with intensity the second half of January followed by a phase_8 to phase_1 shift the first half of February. The phase_8 to phase_1 shift is eastward through the longitudes of the Americas and represents a hot and dry correlation to Australia climate.

The updated 15-day arctic oscillation (AO) forecast maintains a moderate to strong negative phase for the remainder of January eventually causing cold weather in each sector of the mid-latitude northern hemisphere. In Europe, short-term mild climate steadily fades into the deep freeze the last third of January.