Date: 201710
Local time of day: 0601-1200
Location: MLB.Airport, FL
Flight conditions: VMC
Weather elements / visibility: Rain; 10
Light: Dawn
Aircraft: RV-7
Operator: Personal
Operating under: Part 91
Flight plan: IFR
Mission: Personal
Flight phase: Takeoff / Launch
Airspace: Class D MLB
ATC / advisory: Tower MLB
Reporter organization: Personal
Reporter function: Single Pilot
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Flight Engineer
Human factors: Confusion; Situational Awareness; Distraction; Other / Unknown
Anomaly: Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance; Ground Incursion Runway; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Became Reoriented; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Returned To Clearance
Contributing factors: Airport; Human Factors; Weather
Primary problem: Human Factors

Narrative: On departure; I deviated from an ATC instruction unintentionally. I was cleared to depart runway 27L from intersection C. However; I lined up and departed 9R. During [that] time; I was waiting for the thunderstorm that was over the field to move east. I think I was concerned that I would need an early turn north if they were using 9 for departure. (I had not yet received the ATIS at that point).No traffic control conflict occurred. I turned on course and coordinated with ATC IMMEDIATELY while airborne. Never left the airport property. Effectively departing the correct runway direction. I had delayed my departure due to weather over the airport and just north of the airport on my route. I admit that I was fixated on the weather so much that I made this error. All I can think of; as to how I built a mental plan to depart 9R; was that the [ATIS] information J at MLB was 'MLB J 340/04 10 9500 OVC 23/22 29.99. Departure 27L 9L/27R closed 5/23 closed.' My mind clued in on 9 for departure. In fact; I even set my heading bug to 090. Somehow while worried mostly about the weather. I mentally pictured departing 9R at c. Not sure how I made that mistake. As the only 9[L] listed was the closed runway.I was the only aircraft operating in the airport area. Obviously if there was any other departures my flawed mental plan would have self-corrected itself. Typically; when I depart MLB IFR; there is up to a 5 minutes delay from ready to cleared due to coordination with Orlando approach. This departure; I was cleared immediately for takeoff. After my run up; I was again looking at both XM and ADSB Weather; as I called ready for departure. So my focus was not on the runway as it should have been but mostly on the weather. Contributing factors: •	Weather; No other airport traffic before my departure (I was looking as I arrived at the airport and completed my preflight and final weather checks)•	Airport construction; For a 27 departure typically taxi routing would alleviate any confusion.•	ATIS listing the closed runway with 9 listed first.•	Quicker than expected takeoff clearance.How I will change my procedures to ensure never making this mistake again. I do fly for a living. In fact; I will be incorporating the runway verification procedure we use on the jet aircraft at my company into my GA flying from now on. Sadly; I didn't make that procedural change in my GA flying. This is the first significant error I have made in my over 34 years as a licensed pilot in the General Aviation.




Synopsis: RV-7 pilot reported that he took off from the opposite runway than was assigned because of weather and other distractions.