Date: 201907
Local time of day: 0601-1200
Location: DCA.Airport, DC
Weather elements / visibility: Rain
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Takeoff / Launch
Airspace: Class B DCA
ATC / advisory: Tower DCA
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Human factors: Time Pressure; Workload
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight
Result: General None Reported / Taken
Contributing factors: Weather; Company Policy; Human Factors
Primary problem: Human Factors

Narrative: Takeoff with wrong takeoff data and rapidly changing Wx Storms on the departure for runway 01 and tail winds caused tower to change departures to runway 19 at push back time. When we were number 2 for takeoff I realized we would have a wet runway with a tailwind so I asked the FO (First Officer) to setup for a max thrust takeoff. I read the reduced thrust V speeds off so the FO could input them after the speeds were deleted. We planned on a max thrust with reduced V speeds takeoff. I did not however think of getting new takeoff data and we were cleared into position to hold very soon after entering the speeds.Heavy rain began to hit the arrival end of the runway as the plane before us was cleared for takeoff. Tower called winds for the aircraft before us at 020/8. I confirmed that we were limited to a 15 knot tailwind but still did not think of getting new takeoff data for the actual winds. We were cleared for takeoff very quickly after the proceeding aircraft lifted off. The rain was still heavy; but I was able to see them rotate. As we accelerated I was expecting the rain to begin to shear off the windscreen but in fact visibility only got worse as the FO selected high on the wipers. The wipers did nothing to help. Somewhere around the 100 knot callout the rain was now very heavy and I felt it would be more dangerous to abort than to continue. Right as I was thinking this the FO said out loud 'just follow the lights.' I did acknowledged that I could see the lights.By this point we were definitely in the high speed (greater than 100 knots) regime and I was only able to see the centerline lights intermittently. I did not believe we would be able to make a safe abort by this time. It was actually a relief to hear rotate because I was then able to use the PFD. Before we changed to departure frequency I had the FO tell tower that visibility was basically nil for our takeoff in an effort to keep the next airplane from accepting takeoff clearance.Biggest takeaway for me was that I did not get new takeoff speeds before accepting takeoff clearance. After hearing winds for the aircraft taking off in front of us had a tail (020/8) wind we should have told tower we needed new numbers. We were able to get takeoff data after getting to cruise for winds at 020/8. But the Tower called wind for our takeoff as we were rolling at 020/13; takeoff data for theses winds resulted in 'T/O NOT POSSIBLE FEILD LENGTH LIMIT'. We did not and would not normally have the new takeoff data for different winds given as we started the takeoff roll. Even if we ran new data for the 020/8 wind by the time we heard 020/13 as we were rolling and it was too late to know that we were now actually runway limited. Another surprise factor was how fast the amount of rain and wind shift changed in only a moment. I was not thinking about tail winds because the airport just changed runways to avoid tailwinds. I did not feel unsafe until we were already accelerating and the water was not shearing as I have always seen. By that point I felt it would be more dangerous to attempt an abort than continue take off. Looking back I also probably felt an urgency to takeoff. We were in a line of at least 10-12 aircraft lined up to depart before the storm hit.




Synopsis: Air Carrier Captain reported takeoff with wrong takeoff data in rapidly changing weather.