Air Force: Weather OK for NASA, SpaceX launch from KSC on Monday

The weather forecast is mostly favorable for Monday's launch of a SpaceX Falcon 9 rocket with a Dragon capsule destined for the International Space Station, according to the Air Force.

Forecasters with the 45th Weather Squadron on Friday said conditions will likely be 70 percent "go" for the 12:31 p.m. attempt from Kennedy Space Center's pad 39A. The mission will have an instantaneous launch window.

Forecasters cited cumulus clouds and flight through precipitation as their primary concerns for SpaceX's twelfth mission under NASA's Commercial Resupply Services contract, known as CRS-12.

"Still, the time of launch is favorable, since only very unstable days generate deep convection before 1 p.m.," forecasters said.

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Spectators can expect a sonic boom to surge across the Space Coast and rattle windows when the Falcon 9 rocket's 156-foot-tall first stage returns for a propulsive landing at Cape Canaveral Air Force Station's Landing Zone 1 shortly after launch. 

After landing, however, forecasters expect storms to roll through, possibly affecting SpaceX's efforts to secure the first stage, which stands 162 feet tall with its landing legs deployed.

"After landing Monday, storm chances will increase, potentially impacting first stage securing," forecasters said. "Storms should diminish by late afternoon and evening/overnight conditions will be benign."

The CRS-12 mission will take 6,400 pounds of cargo, supplies and science experiments to the crew of the ISS and stay attached to the station for about a month before it splashes down in the Pacific Ocean.

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While SpaceX will introduce smoke and fire at the beginning of the week, United Launch Alliance is expected to do the same on Friday with an Atlas V rocket.

That mission, which will take NASA's newest communications satellite to orbit, is targeting an 8:03 a.m. liftoff from Launch Complex 41 at Cape Canaveral Air Force Station. ULA has 40 minutes to launch the rocket.

The Tracking and Data Relay Satellite payload, named TDRS-M, will help support communications between the ground and other NASA spacecraft such as the ISS and Hubble Space Telescope. 

Contact Emre Kelly at aekelly@floridatoday.com or 321-242-3715. Follow him on Twitter and Facebook at @EmreKelly.

Launch Monday

• Rocket: SpaceX Falcon 9
• Mission: Delivery of Dragon spacecraft to International Space Station
• Launch Time: 12:31 p.m.
• Launch Window: Instantaneous
• Launch Pad: 39A at Kennedy Space Center
• Join floridatoday.com starting at 11:00 a.m. Monday for countdown chat and updates, including streaming of SpaceX's webcast.

Launch Friday, August 18

• Rocket: United Launch Alliance Atlas V
• Mission: Launch of NASA's TDRS-M communications satellite
• Launch Time: 8:03 a.m.
• Launch Window: 40 minutes
• Launch Complex: 41 at Cape Canaveral Air Force Station
• Join floridatoday.com starting at 7:00 a.m. Friday for countdown chat and updates, including streaming of ULA's webcast.