2023 Explanatory Reporting, Medium Newsroom finalist

Explaining California’s Extreme Weather in a Changing Climate

About the Project

Why do heat waves form? Where do atmospheric rivers come from? What risks linger after wildfire flames recede? How does climate change impact extreme weather?

As our planet continues to warm up, extreme weather is increasingly impacting Californians’ daily lives and decision making. Over the last year, The San Francisco Chronicle has focused on explaining the how and why behind extreme weather to answer these important questions and more.

With a new Weather Science team collaborating across the newsroom, The Chronicle produced a series of visually-charged explainer stories that distill complex meteorology and connect the science of heat waves, storms and wildfires to on-the-ground impacts.

When an exceptional heat wave broiled the Bay Area in September, we published a multimedia explainer that answered readers’ questions on the record-breaking warmth. Visually-rich scientific illustrations bolstered data that explained how climate change is impacting heat wave frequency and length.

Thousands of lightning strikes erupted into fast-spreading wildfires that caused unprecedented damage across the Bay Area in 2020. As an exceptional monsoon season arrived last summer with serious thunderstorm potential, fears grew of a repeat. Through judicious data work, reporter Jack Lee found lightning sieges are exceptionally rare in the Bay Area, addressing concerns through rigorous research and reporting.

A cacophony of online chatter on atmospheric rivers came to a roar as a New Year’s Eve storm approached California, bringing with it heavy rains and snow. Before the storm hit, we provided clarity, publishing a story that explained the science instead of regurgitating hype. In this multimedia piece we explained what an atmospheric river is, where such systems come from, why they happen and how our warming planet is changing the intensity of these storms. Graphics localized exactly how such an atmospheric river-fueled storm would travel over the areas where readers live.

Our explanatory coverage of similar systems continued over the next four months as a parade of historic storms affected the Bay Area. In addition to step back projects, we aggressively reported and published science journalism of the moment. We wrote compelling stories using interactive graphics and data visualizations and covered storms live with science-focused forecasts.

We also dug into the interplay between such extreme storms and wildfires. Long after fire turns to ash, burn scars continue to pose disastrous risks — not only to people and infrastructure, but to the watersheds that nourish towns and farms across California. In a warming world, this fire-flood cycle is accelerating, as Hannah Hagemann and Yoohyun Jung reported. We covered these issues at a scale and depth not seen before in local journalism, publishing a project that quantified risk and explained what’s at stake.

Key to The Chronicle’s explanatory effort was our consistent fast-break science stories that explained dangerous weather as it happened. As storms, heat waves and cold snaps impacted Bay Area residents, Chronicle newsroom meteorologist Gerry Díaz continuously broke down the meteorology behind these events with hyper-local “now-casts” and concise explainers that helped our audiences understand the weather affecting their communities.