An escape route is a preidentified path away from an approaching hazard or a deteriorating field position, chosen before the chaser needs it and kept usable at all times. The NWS Skywarn program explicitly recommends identifying at least two exit paths before entering any potentially dangerous area.
How escape routes are chosen
Before pulling into an observation point, the driver and navigator identify roads leading away from the storm in at least two directions, ideally perpendicular to expected storm motion. Four-way intersections are preferred because they offer options in all four cardinal directions.
The routes are then filtered by real-world usability. A dirt road that will turn to mud in the first rain does not count. A bridge just downstream of a rapidly filling creek does not count. A route that runs directly under the storm's forward flank does not count, even if it is technically open.
How they are used
A chaser with a working escape route keeps the engine running, keeps the vehicle pointed toward the route, and keeps a mental clock on how long it will take to reach a safer position. The NWS guidance to avoid the most intense areas of a storm and never drive through the core is built on the assumption that an alternative was chosen in advance.
As the storm evolves, escape routes are re-evaluated. A right-turning supercell can quickly turn what was a safe eastern exit into an intercept course, so the plan is updated in step with storm motion.
Where escape routes fail
Failures cluster around three patterns. The first is committing to a single route and not verifying that a backup exists. The second is waiting too long, so that the chosen route now runs through hail, flood, or debris. The third is convergence, where a road jammed with other chasers or evacuating traffic is no longer usable at speed.
If you are in the threatened region, have a plan to take shelter if a warned storm approaches you. An escape route is not a substitute for a shelter plan, and both should exist before the storm arrives.