SEATTLE — Boeing has announced plans to fly their new Boeing 787-9 aircraft Tuesday morning at 10 AM PST, following completion of the preflight testing program this evening. The flight, like any first flight, is dependent on weather. Forecasts tomorrow in the Seattle area call for a 60% chance of showers and 8-10 knot winds out of the northwest. Boeing is no stranger to inclement weather on first flights.

The first Boeing 787-8 Dreamliner flew its maiden flight in rainy weather back in December 2009. Boeing announced Friday that the flight window was opening Tuesday, but with the taxi tests not occurring until late Monday, most put the first flight on Wednesday. Boeing likely wanted to steal a thunder from its Quebec rival, Bombardier after its CSeries’ successful first flight on Monday, September 16th garnered much attention. Boeing’s first 787-9 test flight comes just over 3 months after the similar sized Airbus A350-900 XWB first flight.

Earlier tonight Boeing began and completed taxi testing of the first airplane late this afternoon under rainy skies. The decision appears to have caught many by surprise as testing did not begin until around 3:45 PM PST as the day was waning, and in poor weather conditions to boot.

Airchive verified from the scene that the airplane did only two taxi tests–one low speed and one high speed–before turning back into its stall on the flight line. It is not clear whether taxi testing is complete, but based on the testing done it very well could be.

Stay tuned to Airchive for developments live from Seattle starting around 0930PT/1230ET! Follow us on Twitter and Facebook LIVE.

More Photos (By Jeremy Dwyer-Lindgren)