BY ERIN CAMPBELL
Iowa was in the path of a record-breaking thunderstorm on Dec. 15, which was later classified as the first December derecho in U.S. history. The state was experiencing unusually warm weather for that time of year, with record-setting highs in the 70s coupled with strong winds. Iowa’s electric cooperatives cautiously monitored the storm system as it moved into southwestern Iowa around 4 p.m. and quickly ripped across the state, leaving northeastern Iowa around 9 p.m.
The National Weather Service (NWS) reported the storm spawned 43 tornadoes in Iowa, setting a new record for the most tornadoes in any single day in the state’s history. Wind gusts topped speeds of 85 mph in some locations. After the storm passed, several strong wind gusts prevailed throughout the night.
A derecho is often described as an inland hurricane, but with no eye and winds coming across in a line. Derechos are more similar to hurricanes than tornadoes in the damage, which is likely to spread over a wide area. According to NWS, a wind damage swath extending more than 240 miles with wind gusts of at least 58 mph along most of its length can be classified as a derecho.
Service outages and interruptions
For Iowa’s electric cooperatives, which serve primarily rural areas, there were 22,500 outages at the peak on Dec. 15. This accounts for approximately 10% of all electric cooperative meters in the state. After the storm, line crews set out to assess the damage and make repairs as best they could in the prevailing wind gusts following the storm.
As the sun rose the next morning, it provided the necessary illumination for crews to better assess the storm’s complete damage. Straight-line winds, tornadic activity, flying debris, and trees, limbs and branches contacting power lines caused broken poles, downed conductors and extensive damage to electrical equipment throughout the state.
“With severe storms like this one, we experienced damage to both the electric transmission system and the local electric distribution systems, which can create extended outage situations,” says Scott Meinecke, director of safety for the Iowa Association of Electric Cooperatives (IAEC).
Mutual aid efforts help restore service
The safety team at IAEC coordinated crews and equipment from unaffected electric cooperatives to impacted co-ops to assist in the power restoration effort.
“We call it mutual aid when cooperatives help other cooperatives in times of need,” explains Meinecke.
Within the first 24 hours of the storm hitting Iowa, power was restored to 18,500 electric cooperative meters. The remaining 4,000 outages were fully restored within the next couple of days.
“We’re always thankful for members’ grace and patience as crews work long shifts to restore power,” says Meinecke. “The damage from this December storm was particularly heavy in some areas and it can be frustrating when we’re not able to provide much detail on when power will be restored. In some cases, crews couldn’t safely head out immediately after the storm because the wind gusts made it too dangerous to be out in the buckets or on the poles.”
A statewide outage map is available at www.iowarec.org to give a snapshot of current outages for Iowa’s electric cooperatives. The outage map is automatically updated every 15 minutes and users can view by county or electric cooperative boundary with a weather overlay layer.
While this storm was one for the record books, Iowa’s electric cooperatives were prepared for the worst and acted quickly to restore power as safely and quickly as possible.
Erin Campbell is the director of communications for the Iowa Association of Electric Cooperatives.
Storm safety reminders
- Never go near or attempt to drive over downed power lines. Assume they are energized and dangerous and notify the electric utility or authorities.
- Obey Iowa law and move over or slow down if you come upon utility crews working on the side of the road. Give them room to work safely.
- Don’t use portable generators in partially covered areas like garages or porches. Only use them in ventilated spaces outdoors to avoid carbon monoxide poisoning.