Updates on NOAA’s Rapid Attribution Capability: The July 2024 California Heat Wave

As climate attribution studies have become more common, routine processes are now being established for attribution analysis following extreme events. This study describes the prototype process being developed through a collaboration across NOAA, including monitoring tools as well as observational and model-based analysis of causal factors. The first prototype of this capability was a stakeholder report on the 2023 summer long heat wave centered near Texas and Louisiana. This presentation will describe how the process has continued to evolve in the subsequent year. It will focus on a shorter but more acute heat wave around California in July 2024.

The California heat wave occurred July 4-13 with its peak around July 7. Several cities set new all-time records including Palm Springs, CA (124°F) and Las Vegas, NV (120°F). The maximum temperature averaged over these 10 days over California was 102.0°F on July 4-13, which exceeded the previous record of 99.3°F from 17-26 July 2006. Unlike Texas/Louisiana, California is a region with an observed warming trend, which simplifies the attribution process. However, this event was also associated with a positive PNA wavetrain, so dynamical processes played a more significant role. This presentation will illustrate how the SPEAR model was used to evaluate the climate attribution of this event.