The countdown is underway for tomorrow's launch of the final Titan 2 rocket on a long-delayed mission carrying a military weather satellite.

Liftoff from Space Launch Complex-4 West at Vandenberg Air Force Base in California is scheduled to occur at 9:17 a.m. local time (1617 GMT; 12:17 p.m. EDT) at the opening of a 10-minute window.

The Defense Meteorological Satellite Program F16 spacecraft should arrive in its 458-nautical mile circular orbit around Earth's poles about 15 minutes and 20 seconds after launch.

Countdown clocks for the mission began ticking at 7:17 a.m. this morning from the T-minus 26 hour mark.

Officials told reporters at a mid-morning news conference there were no technical problems are being addressed.

"Often times when we're getting ready for launch there's an issue or two still open that needs to be resolved. In this case, we have none of those," said Lt. Col. Dave Thompson, commander of the 2nd Space Launch Squadron at Vandenberg.

The weather forecast is still calling for acceptable conditions with only a 10 percent chance of winds posing a problem for rolling back the mobile service tower Wednesday morning and at launch time.

"Zonal flow across the Pacific dominates the weather pattern for the upcoming week," Launch Weather Officer Lt. Breea Lemm reported this morning. "At the surface, weak on shore flow has reestablished the marine layer to the south, expect this marine layer stratus to creep along the coast and be in place over SLC-4W at T-0. With the marine layer overhead and light northwesterly winds at the surface, visibilities will be slightly degraded at launch time.

The launch conditions are expected to include stratus clouds at 700 feet with 5/8ths sky coverage and tops at 1,100 feet, visibility of three nautical miles, northerly winds from 350 to 020 degrees at 5 to 10 knots, a temperature of 53 to 58 degrees F and fog in the area. Upper level winds will be from the west with a maximum of 65 knots around 45,000 feet.

In the event of a 24-hour delay, the forecast for Thursday calls for an 80 percent chance of acceptable weather conditions. Winds remain the only concern.

"The weather pattern for Wednesday holds true on scrub day," the launch weather officer said. "Zonal flow remains aloft, with the marine layer once again present in the lower levels. Above the marine layer, a thin layer of cirrus will be present at 30,000 to 32,000 feet. The surface gradient tightens slightly, expect surface winds to increase to 8-12 knots from the northwest. Upper level winds continue to flow from the west, reaching a maximum of 70 knots near 45,000 feet. Temperatures will remain in the upper 50's and low 60's, and no precipitation is expected."