Delta IV Heavy 90 Percent "Go" For Saturday

A top-secret national security mission is scheduled to get under way Saturday evening with the launch of a giant Delta 4 Heavy rocket at Cape Canaveral Air Force Station, and the weather looks as if it will be good enough to go.

The United Launch Alliance rocket is scheduled to blast off from launch Complex 37 at 7:33 p.m. EST, and the launch window Saturday will extend to 11:33 p.m.

The weather forecast for launch is excellent: Air Force Weather Officer Joel Tumbiolo says there is a 90 percent chance that conditions will be acceptable for launch. The prime concern will be ground winds and the possibility of thick clouds over the launch complex.

Check out all the details here: Launch Forecast

Mission managers will be keeping close tabs on the winds early Saturday. There is a chance winds could hold up the rollback of the mobile service tower at complex 37.

The Delta IV Heavy is slated to haul up a classified payload for the National Reconnaissance Office -- the super-secret agency that owns and operates the nation's fleet of spy satellites.

We'll have countdown updates all day Saturday, and we'll also webcast United Launch Alliance coverage of the launch starting about 25 minutes prior to liftoff. You'll see a video player at the top of the blog. Simply click on it to watch the launch live. And as always, be sure to refresh this page for periodic updates.