Question 1

What does the SEEM footprint cover?

Accepted Answer

The Southeast Energy Exchange Market launched in October 2022 as a bilateral automated energy exchange that allows participating southeastern utilities to trade energy in 15-minute intervals across an aggregated footprint. Member entities include Duke Energy Carolinas, Duke Energy Progress, Southern Company subsidiaries (Alabama Power, Georgia Power, Mississippi Power), the Tennessee Valley Authority, Dominion Energy South Carolina, Associated Electric Cooperative, and several other public power and cooperative utilities. SEEM is not a traditional ISO — there is no centralized day-ahead or real-time energy market and no capacity auction; member utilities remain vertically integrated under state regulatory oversight.

Question 2

What does the Southeast generation mix look like?

Accepted Answer

The southeastern utility footprint relies on a balanced mix of nuclear (the Southeast hosts Vogtle, Watts Bar, Sequoyah, Browns Ferry, McGuire, Catawba, Brunswick, Harris, Robinson, Farley, Hatch, and the Summer site), natural gas combined-cycle (rapidly displacing retired coal units), TVA hydroelectric (the Tennessee River dam system providing both energy and flexibility), and growing utility-scale solar across Georgia, North Carolina, and Florida. Coal retirements continue to accelerate, with Plant Bowen and other large Southern Company units on retirement schedules. Pumped storage at Bath County (Virginia, Dominion side) and Raccoon Mountain (TVA) provides multi-hour flexible discharge.

Question 3

What weather events most stress the Southeast grid?

Accepted Answer

Hurricane preparedness and restoration is the defining grid challenge. The region's investor-owned utilities have well-developed mutual aid networks and pre-positioned restoration crews that can reach landfall zones within hours, but Category 4 and 5 landfalls produce multi-week outages in the most severely damaged areas (Helene 2024, Ian 2022, Michael 2018, Florence 2018, Andrew 1992). Winter cold snaps periodically test the system — TVA invoked rolling outages during the December 2022 Arctic outbreak, the first time in its history. Ice storm restoration in the Piedmont and Tennessee Valley can take weeks, and severe convective weather across Dixie Alley brings tornadoes and damaging winds in spring and late fall.

Question 4

How does the National Hurricane Center forecast Southeast landfalls?

Accepted Answer

The National Hurricane Center publishes Tropical Weather Outlooks every six hours during hurricane season (June 1 to November 30) and full advisories every six hours once a system becomes a tropical depression. Hurricane Watches are issued 48 hours ahead of expected onset, Hurricane Warnings 36 hours ahead, alongside Storm Surge Watches and Warnings for the coastal counties. The Southeast routinely sees the most landfalls of any U.S. region — Helene in 2024, Ian in 2022, Michael in 2018, Florence in 2018, Andrew in 1992 — and the NHC's five-day cone is the primary planning tool for utilities pre-staging crews.

Question 5

What weather alerts dominate Southeast summers?

Accepted Answer

The NWS issues Heat Advisories across Atlanta, Charlotte, Birmingham, Memphis, Nashville, and the Florida metros when forecast heat indices reach 105°F to 109°F for two or more hours, and Excessive Heat Warnings at 110°F or higher. Sustained heat indices above 100°F with overnight lows in the high 70s — common across the humid subtropical Southeast through July and August — drive the most consequential summer cooling demand. Severe Thunderstorm Warnings and Flood Warnings accompany the strong cold fronts that periodically break the heat.

Question 6

How are ice storms warned for across the Piedmont and Tennessee Valley?

Accepted Answer

Ice storms occur when warm air aloft overruns a sub-freezing surface layer, producing freezing rain that accretes on conductors and tree limbs. The NWS issues Ice Storm Warnings when ice accumulations are expected to reach a quarter inch or more — enough to bring down tree limbs and weaken overhead lines. The Piedmont (central North Carolina, central South Carolina, north Georgia), the Tennessee Valley, and northern Alabama are particularly prone, and damage spread across thousands of distribution feeders typically takes weeks to fully restore.

Question 7

What weather drives Southeast winter cold events?

Accepted Answer

Periodic Arctic outbreaks push freezing temperatures all the way to the Gulf coast a few times each winter. The NWS issues Wind Chill Advisories and Wind Chill Warnings, plus Hard Freeze Warnings for the agriculture sector across central Florida and south Georgia when temperatures are expected to fall below 28°F. The December 2022 Arctic outbreak that forced TVA's first-ever rolling outages produced sustained sub-freezing temperatures across the entire Southeast for several days and remains the modern reference event.

Question 8

How are tornadoes and severe weather warned for across the Southeast?

Accepted Answer

The Storm Prediction Center publishes daily convective outlooks (Marginal through High Risk) flagging severe-weather potential, with Tornado Watches and Severe Thunderstorm Watches typically preceding individual storms by hours. Tornado Warnings are issued in real time based on radar-detected rotation or trained spotter reports. The Southeast's secondary tornado season runs from late October through early December and overlaps with the primary spring season across Alabama, Mississippi, Tennessee, and Georgia — the so-called 'Dixie Alley' has produced some of the deadliest tornado outbreaks in U.S. history.

Question 9

What sources are referenced for the historical events on this page?

Accepted Answer

Specific event references on this page (Hurricanes Helene 2024, Ian 2022, Michael 2018, Florence 2018, Andrew 1992, the December 2022 Arctic outbreak that forced TVA's first-ever rolling outages) are drawn from the National Hurricane Center's Tropical Cyclone Reports at nhc.noaa.gov, NWS event summaries from the affected forecast offices, the FERC and NERC Inquiry into Winter Storm Elliott (October 2023), and TVA's public statements and board materials following the December 2022 event.

Metric	Actual	Normal	Departure
CDD	1262.5	720.5	+542.0
HDD	1244.3	1654.5	-410.2

SEEM

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Recent History (7 days)

SEEM (Southeast Energy Exchange Market) — Frequently Asked Questions

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