What is StormSync VT/OI?
A free Windows app that reads the National Weather Service's live alert feed and decodes it on your own PC. Here is how it works, what it covers, and what it does not do.
Built on NWWS-OI.
The NWS sends alerts out through several channels. Most weather apps check the public API at api.weather.gov on a timer, so there is usually a 60 to 120 second gap between a warning being issued and the app finding out.
StormSync connects to the NOAA Weather Wire Service Open Interface (NWWS-OI) instead. It is a login-protected XMPP feed that broadcasters, emergency managers and commercial alert services use. Nothing polls. The NWS pushes each product out as it is published, and it usually reaches a connected client within about 100 milliseconds.
The same wire is used to trigger the Emergency Alert System on TV. StormSync is a free desktop app for it.
How it works.
While it is running, StormSync keeps one XMPP connection open. The wire works like a single one-way room: a service account posts each product as a message with the raw text, and every connected client gets it at the same moment. Every text product from every Weather Forecast Office and National Center comes through.
StormSync then parses each product on your PC. It reads the VTEC codes, UGC zones, phenomenon and significance, and works out a severity. Tornado warnings are split into five types (Emergency, PDS, Confirmed, Observed and Radar Indicated) and ranked from 1 to 115.
Everything it receives is saved to a local SQLite database. Your alert history stays on your PC.
Where it works.
StormSync shows what the National Weather Service issues, so its coverage is the United States and its territories. It does not have alerts for other countries, because those do not come from the NWS.
You can run it from anywhere that has an internet connection and allows outbound port 5222. You see alerts for the whole feed, and the toolbar lets you filter by state or search by keyword.
Central Feed or your own account.
Central Feed is the easy way and needs no credentials. I keep one connection to NWWS-OI open with my own NWS account and pass the raw alert text on to the app. Your app parses it on your PC, as always. Your own credentials are never involved, and the relay adds a short delay that you will not notice. The relay runs on a dedicated server built for 24/7 uptime, so the connection is very stable.
Private Feed is for anyone who wants a direct connection with no relay at all. You ask the NWS for your own NWWS-OI account by emailing [email protected]. It is free, usually takes 10 to 30 days, and the account belongs to the person who applied for it. Put the username and password in the app's connection settings. They are saved on your PC only.
When the wire moves, or breaks.
NWWS-OI runs behind two domain names, and the NWS switches servers from time to time for patching. When that happens, clients have to reconnect. StormSync does this automatically instead of sitting on a dead connection, and it shows the connection state in the app so you can tell whether you are actually listening.
Central Feed is one relay run by one person, so it can have problems of its own. Planned downtime is posted on the maintenance page. If you need something that does not depend on me, use a Private Feed. The performance log records how each version did during real severe weather, including the bugs.
What it is not.
- It is not an official NWS or NOAA product, and it is not affiliated with either.
- It is not a replacement for official warning systems like Wireless Emergency Alerts or NOAA Weather Radio. Do not rely on it alone when your safety is involved.
- It is not full radar software. The built-in radar is for quick checks.
- It is Windows only for now, and it is made and supported by one person.
Who it is for.
Weather enthusiasts, storm spotters, hobby meteorologists, storm streamers, and anyone who wants NWS alerts quickly and in detail. It is free, there is no subscription, and with Central Feed there are no credentials to sort out.