Storm Analysis: ERCOT’s Intense May Weather

The storm in ERCOT last Thursday left nearly one million people in eastern Texas, particularly in Houston, without power for days. These extreme weather events seem to be much more frequent and powerful. Straight line winds appeared to be the main culprit for this storm, with an EF1 tornado mixed in. When looking at actual demand numbers from this event, you can see the immediate drop throughout HE18-HE20 once this storm strengthened, and winds started rolling into populous regions like Houston. Demand completely diminished not just because of the after-dark cool down, but because of the 1 million Houston residents that lost power because of this intense storm. This storm rolled in after Friday, the 17th's DA market cleared, disrupting everyone's DA demand forecast for the 16th and 17th.  

When comparing the accuracy of our forecasts, Amperon's MAPE was consistently better than ERCOT's during these days. These MAPEs are high due to the DA forecast being locked in at 10 am the day prior, as well as the next day's DA forecast being locked in already as well.

However, our forecast was retrained for the weekend, resulting in better MAPE scores for the 18th and 19th, even with power outages still incorporated. Our historical vintage forecasts leading up to May 17th's   peak demand hour, HE18, show that the intraday iterations of the real time hourly forecast were much closer to actual demand values due to the updated load data/load capacity. The forecast for May 17 was instantaneously downgraded once the storm had already rolled through the region, causing widespread power outages. This dynamic hourly forecast is a key feature for Amperon’s accuracy. Even though the May 17th DA forecast was locked in without incorporating the power outages, Amperon’s hourly updates ingest the most recent demand and weather data, resulting in a more accurate real time forecast during unpredictable events like these. These vintage forecasts can be visualized in the graph below. The graph shows that starting May 16th at HE21, the hourly forecast for May 17th HE18 (peak demand hour) was already ingesting the updated demand numbers, incorporating the power outages that had occurred the hours prior.

Intense unpredictable weather events, like this intense storm, highlight the importance of accurate forecasting and preparedness, especially as we approach hurricane season. Amperon strives for accuracy and is always reanalyzing extreme weather events to improve our forecasting abilities. Contact us to learn more.

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