The following information is valid as of 2018 December 19 at 12:34 PST:
This evening's planned launch of a Delta IV Heavy rocket from Vandenberg AFB appears to be on schedule. Liftoff is slated for 5:44 p.m. PST from south Vandenberg. The most recent weather forecast called for an 80% probability of acceptable weather at launch time.
If the sky is clear, the launch could be visible over a wide area. Computer simulations by Rick Balrdridge show if the rocket is launched on time, it will climb into sunlight at high altitude during the powered portion of the launch at T+ 4 minutes 20 seconds. In other words, the rocket's exhaust plume should be illuminated by the sun with a dark sky as a background.
For launch and countdown status and launch coverage, go to: