Grid operators across a wide swath of North America are keeping one eye on the weather and another on the electric power ecosystem as the season’s first big winter storm is forecasted to sweep across much of the U.S. and southern Canada in the days leading up to the Christmas holiday. NERC said that while the grid had a sufficient supply of capacity resources under normal winter conditions, it was “concerned that some areas are highly vulnerable” to extreme and prolonged cold. As a result, “load-shedding may be required to maintain reliability.” The Midcontinent Independent System Operator (MISO) issued a report on fuels and consumables as of December 19 that forecast “normal system conditions” for the next week. The report forecasts a jump in total demand to just under 100 GW on December 24th as temperatures across the region are expected to plummet. Demand peaks in excess of 90 GW are forecast for December 23-25. As of mid-morning on December 21st, the total load was 89,785 MW, around 1,000 MW above the forecast load. The MISO has retired more than 4.2 GW of nuclear and coal-fired generation since last winter, with few resources added. Consequently, reserve margins in the region have fallen by more than 5%. It said that an extreme cold-weather event that extends deep into MISO’s area could lead to high generator outages from inadequate weatherization in southern units and unavailability of fuel for natural gas-fired generators.