What a hurricane season taught me about quiet failures

StormWatch is the emergency weather app I build and run for Hawaiʻi. iPhone, Apple TV, Apple Watch, and the web. Free, no account. I started it because the information was scattered across the Weather Service, the Hurricane Center, USGS, and the tsunami centers, and nobody had put it in one place.

This season was the first real test. In August I shipped the biggest update yet: a live radar loop, hurricane forecast cones from the NHC drawn on the map, and alerts on the Lock Screen that update on their own, even when the app is closed. Then Lala showed up on the map, and I found out what I had gotten wrong.

The first lesson came from a feed that had been wrong since the beginning. StormWatch read tsunami alerts from the National Tsunami Warning Center. That center is in Alaska, and it covers Alaska and the mainland coasts. Hawaiʻi is covered by the Pacific Tsunami Warning Center, a different feed. Nothing had ever looked broken. The feed was clear, and clear looks the same whether you’re watching the right ocean or the wrong one.

The second lesson had the same shape. When the Weather Service feed goes down, StormWatch keeps running and shows only the alerts I’ve entered by hand. That’s the right call for an emergency app: fail open, never blank. But a clear feed and a dead feed looked identical. Now the response says when it’s degraded, so the app and the alert pipeline can tell “nothing is happening” from “I can’t see.”

The third came from the ground. During an outage, the first thing people want to know is whether it’s just their house. In September I added community outage reports. Tap the map, drop a pin, no account, no name. The part I like most is small. If you have no signal, the report waits on your phone and sends itself when a connection comes back.

For people with almost no signal at all, there’s now a text-only version of the whole board, built for portable network kits and weak cell links. And twenty water-level sensors in loko iʻa fishponds and streams, Heʻeia, Waikalua, Moliʻi, joined the stream gauges, because the water reaches those places first.

The failures that worry me now aren’t the loud ones. A crash gets reported. A feed pointed at the wrong ocean doesn’t. So I ask the same question of every data source now: if this went quiet, how would I know?