Power Outage Report - May 28, 2024 Texas Derecho

A brutal severe weather spring in Texas culminates in a 1M+ power outage event.

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To date, 2024 has featured one of the most active severe weather seasons in recent years.? Through June, this severe weather onslaught has placed 2024 just behind the historic year of 2011 in tornado and wind damage reports within the previous 15-year record.? Much of this severe activity has targeted the Plains and, surprisingly, the Upper Midwest, where StormImpact’s home state of Ohio has recorded a staggering 67 tornadoes through the end of May (just five shy of Oklahoma!).

Further south, Texas has also experienced a particularly brutal spring.? Through May, Texas has notched 96 tornadoes—just shy of Iowa’s 98 as the 2024 U.S. tornado leader.? However, the Texas tornadoes have not been the primary pain point for power outages in the state.? While tornadic winds can be catastrophic to a confined area, severe winds from lengthy bowing fronts can produce far more widespread damage at wind speeds equal to low-end tornadoes (as the old saying goes for TV meteorologists across the country, wind is wind!).? Perhaps most notably, two derechos in Texas during the month of May resulted in catastrophic damage to power infrastructure, resulting in millions of customers without power.? The National Weather Service defines a derecho as a “widespread, long-lived wind storm” that is typically associated with a convective front, or a band of rapidly-moving storms.? The winds unleashed by a derecho can reach hurricane strength, crippling power infrastructure in its wake.

On May 16-17, a derecho brought 100 mph winds to the Houston area, resulting in $1.2 billion in damages, 8 fatalities, and knocking out power to hundreds of thousands of customers, many of whom had no power for over a week.? Just over a week later, Texas experienced yet another derecho.? The May 28 East Texas derecho was a much more widespread event than the May 16-17 derecho, largely spanning regions between and including Dallas and Houston.? Figure 1 shows the derecho wind damage reports across eastern Texas for May 28.

The derecho initiates in the early morning hours near the Dallas-Ft. Worth metro area.? The convective front then blasts to the southeast, reaching the Houston area roughly seven hours after its formation.? Meanwhile, in northern Texas, severe thunderstorms producing strong winds, frequent lightning, heavy rain, and hail initiate behind the main derecho front.

The performance of Texas utilities during damaging storms or events that place extreme load on the grid often fall under particular scrutiny.? ERCOT, the organization responsible for generating 90% of the state’s electricity, is almost entirely isolated from the rest of the United States.? As regional disasters unfold across the state, the isolation of the Texas power grid leaves few fallback options for electricity generation.? Such was the case during the 2021 Texas winter storm that resulted in a stunning $195 billion in damages, over 240 deaths, and the near-collapse of the Texas power grid.

How did Texas utilities fare during this particular onslaught of severe weather?? StormImpact’s national power outage monitoring project recorded the event in real time, giving us considerable insight into the event.? Figure 2 shows the animated radar and corresponding power customers affected during the May 28 derecho.? It is striking to see how rapidly power outage reports pour in during the immediate aftermath of this fast-moving storm, aligning well with the wind damage reported in Figure 1 and the most intense portions of the convective front.? Meanwhile, the explosion of storms in the Texas panhandle results in widespread outages.? Post-storm surveys by the National Weather Service in the panhandle uncovered damaged utility poles from estimated 90-120 mph winds.

We can view this data in a different way.? Figure 3 shows power outages across Texas aggregated across all tracked utilities, and Figure 4 shows these data disaggregated by utility.? The data show that Oncor, the major electricity provider in the affected regions of eastern Texas, was by far most affected by the derecho.? Significant outages in the Dallas-Ft. Worth metro area result in an immediate spike in outages to almost 400,000 Oncor customers affected.? By May 31, restoration efforts bring this number to below 50,000.? Statements by Oncor in the aftermath of the storm reflect the considerable damage incurred, with representatives calling May 28 the second-worst day in over a century of operation, and the worst ever experienced in the Dallas-Ft. Worth metro.

To put the magnitude of customers affected shown by Figure 4 into perspective, Figure 5 shows the peak outages experienced on May 28 as a fraction of customers served in Texas for selected utilities.? Oncor, despite representing the bulk of Texas outages, only shows about 10% of its customer base affected by the derecho.? Smaller regional utilities, like Rita Blanca Electric Cooperative and Sam Houston Electric Cooperative report about 15% and 11% of customers affected, respectively.? Xcel Energy Texas, a major power provider to the Texas panhandle, registers the highest fraction of outages at over 25% of their Texas customers.

As a volatile spring comes to a close, severe weather season is not over yet.? While a period of relative severe weather calm has finally reached much of the weather-prone United States, hurricane season has officially begun and has Texas in its crosshairs.? Recently, Tropical Storm Alberto brought heavy rain and flooding to southern Texas.? StormImpact will continue to monitor Texas utilities in what has become a devastating year for the Lonestar State.

Scott D. Hull, Ph.D.

Data shown are sometimes preliminary estimates and may not reflect the exact number of customers affected.

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