CAPE CANAVERAL, Fla. — Thunderstorms are threatening to delay NASA’s planned launch tonight of space shuttle Endeavour, already running a month late. Forecasters say there is a 60 percent chance that storms could force a postponement.

The shuttle and its crew are set to deliver and install the third and final piece of Japan’s $1 billion space station lab, named Kibo, Japanese for hope. The first two sections flew up last year. Five spacewalks are planned during the 16-day flight.