According to Operations Messages on the ERCOT website, around 5 a.m. ERCOT issued a Transmission Emergency in South and Southeast Texas.

That happened early Tuesday, when ERCOT called on about 4,000 megawatts of battery storage to help meet the morning demand crunch. Those same batteries were charging up during the day to be ready for when the sun goes down and demand spikes again for the evening temperature drop.

Areas around Houston could receive up to six inches of snow, which would rank among the heaviest snowfalls ever for the city. Winter Storm Warnings stretch as far south as the Rio Grande.

ERCOT, Electric Reliability Council of Texas, issued a weather watch advisory ahead of the arctic blast hitting Texas this weekend. The weather watch advisory will be from Monday, January 20 to Thursday, January 23. The state grid warns Texans the cold weather could cause a higher electrical demand and the potential for lower reserves.

Below-freezing temperatures will return to Texas as soon as Jan. 18, according to the National Weather Service. Grid conditions are expected to be normal and officials do not anticipate an emergency,

ERCOT issues a Weather Watch for Texas due to an arctic blast, preparing for higher electricity demand, but expects the grid to remain stable.