Reading the Map
Everything you see on the Live tab, explained. Those colored shapes have meaning — here's how to read them.
What Are Those Colored Shapes?
Those shapes are warning polygons. When the National Weather Service issues a warning, they draw a shape around the specific area that's in danger. Each color means something different:
Red — Tornado Warning
A tornado has been spotted or detected on radar. This is the most urgent alert.
Orange — Severe Thunderstorm Warning
A storm with damaging winds (58+ mph) or large hail (1"+) is happening. No tornado, but still dangerous.
Yellow — Tornado Watch Zone
Conditions are favorable for tornadoes in this large area. Stay alert but no immediate danger.
Why Shapes Instead of Counties?
The old system warned entire counties. The problem? A county can be huge. You might get a warning even though the tornado was 50 miles away from you.
Now, the NWS draws a polygon — a precise shape around just the area that's actually threatened. This means:
- •More accurate warnings — you only get alerted when the danger is actually near you
- •Fewer false alarms — no more county-wide warnings when only one corner is affected
Why Do Polygons Change Shape?
Storms move. As a tornado-producing storm travels, the NWS updates the warning polygon to follow it. You might see the polygon shift, grow, shrink, or change direction — that's the forecasters tracking the storm in real time.
When you tap on a warning, you can see the polygon progression — an animation showing how the warning area changed over time as updates were issued.
The dashed blue outlines show where the warning polygon was earlier. The solid red shape is where the threat is now. You can see the storm tracked east across Fairfield toward Mount Carmel.
What Happens When You Tap a Warning?
Tapping any warning (on the map or in the list) opens a detail view that shows you:
- •The full warning text from the National Weather Service
- •Affected areas — which counties and cities are in the polygon
- •Timing — when the warning was issued and when it expires
- •Polygon history — how the warning area changed over time
Tapping a warning shows the location, radar overlay, population affected, timing, and source. Hit "View Details" for the full NWS warning text and polygon history.
The Pulsing Red Dot
See a pulsing red dot at the top of the Live screen? That means there are active tornado warnings right now somewhere in the US. The number next to it tells you how many active warnings there are.
No dot? That means there are currently no active tornado warnings. That's a good thing.
Active vs. Expired
Active warnings are currently in effect — the danger is happening now or is imminent.
Expired warnings have ended. The danger has passed. You can still review expired warnings to see what happened — tap the "Expired" section to browse past warnings by date.
