| Upshot–Knothole Grable | |
|---|---|
 | |
| Information | |
| Country | United States |
| Test series | Operation Upshot–Knothole |
| Test site | Nevada Test Site |
| Date | May 25, 1953 |
| Test type | Atmospheric |
| Yield | 15 kt |
| Test chronology | |
Upshot–Knothole Grable was a nuclear weapons test conducted by the United States as part of Operation Upshot–Knothole. Detonation of the nuclear weapon, a W9 warhead, occurred 19 seconds after its deployment at 8:30am PDT (1530 UTC) on May 25, 1953, in Area 5 of the Nevada Test Site.