UPDATE: Cold Weather Alert Extended to Tuesday


PJM Interconnection has extended its cold-weather alert to noon on Tuesday for its entire footprint.

PJM, operator of the nation’s largest electrical grid and wholesale electricity market, on Friday issued two separate cold-weather alerts for the holiday weekend, one for Sunday in the Western Region and one for Monday’s Martin Luther King Jr. Day, for all of PJM’s 13-state footprint.

The Sunday alert was from 7 a.m. Sunday through midnight for the Western Region, which includes all or parts of Illinois, Indiana, Kentucky, Maryland, Michigan, Ohio, Pennsylvania Tennessee, Virginia and West Virginia.

The second alert, for all of Monday, has been issued for the entire PJM service area, which also includes all of New Jersey, Delaware, Washington, D.C., and part of North Carolina.

Much of the PJM footprint is expected to experience a “flash freeze,” where precipitation is followed by a rapid fall in temperature, according to the National Weather Service. These cold temperatures can impair the start-up of plants that aren’t already running. Temperatures on Monday morning are expected to dip to -7 degrees in Columbus, Ohio, -2 degrees in Pittsburgh and 4 degrees in Trenton, N.J.

Electricity demand is expected to reach 127,000 megawatts by Monday evening – that’s nearly 20 percent more than the expected load forecast for Friday (1/18).

PJM Winter Preparations

PJM and its members are prepared to meet the forecasted winter electricity demand in the nation’s largest high-voltage power grid. PJM expects to have 185,611 megawatts of resources available to meet the forecasted peak demand of 135,506 MW. PJM’s all-time winter peak is 143,295 MW, set on Feb. 20, 2015.

A cold weather alert prepares personnel and facilities for expected extreme cold weather conditions, when actual temperatures fall near or below 10 degrees Fahrenheit.

Track grid conditions in real time with the PJM Now app on iOS and Android.

PJM communicates with generator owners and tells them to be prepared to call in additional staff to get all generating units running for the morning load pickup. They must take extra care to maintain the equipment so that it doesn’t freeze in the cold weather. During a cold weather alert, PJM also cancels or postpones planned maintenance outages to ensure the availability of resources.

PJM is prepared to meet electricity needs amid a less-certain winter weather forecast. While climate models suggest a warmer season, studies of similar seasons suggest near- to below-average temperatures. Additionally, the arctic air mass known as the “polar vortex” may weaken later in the season, which could lead to short periods of arctic cold. A weaker polar vortex allows arctic air to travel farther south than it normally would.

The cold snap of Dec. 28, 2017 through Jan. 7, 2018, produced one of PJM’s top 10 winter peak demand days of all time (Jan. 5, 2018, peak of 137,522 MW at 7 p.m.). PJM reported (PDF) that generation and transmission performed well under adverse conditions during that period. Even during peak demand, PJM had adequate reserves and capacity available, and Capacity Performance market rules resulted in more efficient and dependable generator performance.

Learn more about how PJM prepares for winter conditions on the PJM Learning Center.