How to read the map
Enter a US city or ZIP code and the map shows potential targets around you and where today's winds would carry fallout from each.
The headline
The line at the top answers the main question: of the potential targets near you, how many could send fallout over your location with the current wind forecast. It names them and gives a rough estimate of the earliest that fallout could arrive.
Fallout paths
Each target has a shaded path estimating where fallout from a ground burst there could land.
- Red, solid: the estimated path crosses your location.
- Red, dashed: you are close to the edge of the path. Fallout patterns are irregular, so treat an edge as a possible hit.
- Gray: the path misses you.
- Hollow ring: a city set to an air burst, which produces little local fallout and so has no path.
- Dotted circle: the extent of a missile field, which would take many ground bursts across a wide area.
Paths bend because the winds change from place to place and hour to hour. Each path is followed for up to 12 hours of travel.
The results table
The table lists each target with its result, an estimate of the earliest fallout could reach you, how far away it is and in which direction, and where its fallout is heading. Arrival estimates use the fastest of the winds involved, so they tend to be early. They are model output, not a basis for real decisions.
Size and Cities switches
Size sets the assumed weapon for single targets. A larger weapon lifts its cloud higher, into different winds, and spreads fallout further: paths are drawn to about 60 miles for 10 kilotons, 150 miles for 100 kilotons and 300 miles for 1 megaton. These distances are settings chosen for this model, not measured limits. Missile fields are always shown with a heavier, longer-reaching path.
Cities switches metro areas between a ground burst, which is the worst case for fallout, and an air burst, which is thought more likely against cities and produces little local fallout.
Next 48 hours
The strip of times shows how many targets would send fallout to you at each point over the next two days. Select a time to redraw the map for it. A blue dot marks rain or snow, which can wash fallout down in unpredictable hotspots.
Winds above you
The table at the bottom shows the wind at each altitude over your own location. "Upwind of you" at the top of the page summarizes it: a burst anywhere in that direction, whether on the list or not, would send fallout toward you.
How much to trust it
Many factors affect where fallout travels and how dangerous it is. This educational tool takes only three into account: the forecast winds from the ground up to the top of the mushroom cloud, an assumed weapon size, and an assumed burst type (on the ground or in the air). Everything else is left out, including the weapons actually used, the radiation dose, the hotspots that rain creates, terrain, and errors in the forecast. The map shows what is likely, not what is certain. Read how it works for the method and its limits.