WXA/SA - said “wixsa” - is WxAlerts’ own storm analysis. The rest of the site carries what the National Weather Service issued. This is the part that looks at the storms themselves.
Every two minutes it picks out every convective cell in the lower 48, scores how likely each one is to produce severe weather, matches it to the same physical storm it was watching two minutes ago, and projects it forward along its own measured motion. The rotations inside those cells are found and tracked separately, because a storm can be 59 km across with its spin confined to one corner.
There are two things to do with it:
- Watch it. Turn on the Storm cells layer on the live map. What the shapes and colors mean →
- Be told about it. Storm notifications are opt-in, per device, per saved place, with a band you choose. How many times one storm is allowed to wake you →
What it tells you
One sentence, on the map and in every notification:
This storm has rotation and a high probability of producing damaging wind, hail or a tornado.
Never “a tornado is happening in this cell.” That is the measurement, not squeamishness. The same storms at the same threshold, scored two ways:
| Hit rate | False alarm | |
|---|---|---|
| As a tornado call | 42% | 58% |
| As a severe-hazard call | 85% | 15% |
The narrow claim is the one people want, and it cannot carry its own false-alarm rate at any threshold that fires often enough to be a product. So the layer, the API and every notification make the wide one. Where those numbers come from →
The alert levels
Five levels ship, from least to most serious:
| Level | What it means |
|---|---|
| Thunderstorm Risk | A storm capable of severe weather is heading this way |
| Thunderstorm Detected | A severe storm is on you now |
| Tornado Risk | This storm is rotating and is capable of producing a tornado |
| Tornado Risk (high) | Rotating, with a high probability of severe weather |
| Tornado Detected | A rotation has been located and its path covers you |
Detected outranks Risk within a hazard, and the tornado levels outrank the thunderstorm ones. A located rotation whose cone covers your point is more actionable than a probability on the parent cell.
None of these are NWS product names. “Warning” and “Advisory” are product classes with legal definitions attached, and Tornado Warning and Wind Advisory are NWS products verbatim. Every level here names what an instrument observed and instructs nobody to do anything, which is the NWS’s job.
How early it is
Of the severe storms already warned tonight, these are the ones becoming tornado-capable, flagged a median 45 to 54 minutes before a tornado warning is issued on them, with the rotation located to within a couple of kilometers.
That is a triage claim, not a detection claim. On the largest tornado day of 2026, 91 of our 94 cell firings already had a Severe Thunderstorm Warning in force, a median 99 minutes before we fired. The forecasters were on those storms long before us, with the correct product. What they did later was upgrade, and upgrading is the moment we are early to.
What the lead-time numbers do and do not claim →
Where to go next
Using it
- Reading the map: what the cells, tracks and cones on /live actually mean.
- Notifications: the bands, and how many times one storm is allowed to wake you.
- Level II radar: every tilt in the app, and the debris badge.
Under the hood