Date: 201911
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Weather elements / visibility: Turbulence; Windshear
Light: Daylight
Aircraft: B737-700
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Takeoff / Launch
Airspace: Class C ZZZ
ATC / advisory: Tower ZZZ
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Human factors: Communication Breakdown; Workload
Anomaly: Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Returned To Clearance
Contributing factors: Company Policy; Human Factors; Weather
Primary problem: Human Factors

Narrative: Upon receiving clearance to line up and wait on ZZZ XXR; ATC began relaying wind shear alerts at the departure end of our runway. We were already evaluating the weather cells off that same end. They appeared to be nothing more than heavy rain; similar to what we had experienced on our earlier arrival. The cells were a few miles east of us moving slowly to the southeast. Tower asked us if we were able to depart under the existing conditions. As a crew; we discussed the Tower wind shear alert and what might be a fairly clear path for our turnout if we elected to go. Based on the current situation we agreed that delaying our takeoff was the best course of action. I notified Tower and the Controller directed us to exit the runway. However the Controller then relayed that the previously detected wind shear had moved off of the field and out of our path. He went on to let us know that if we could accept a turn on departure to the north; then we should stay clear of any heavy precipitation on his radar. That agreed with what I was seeing visually so; with the FO's (First Officer) concurrence; I let him know we were ready for takeoff as long as he was able to clear us for an immediate turn. Tower then cleared us for takeoff with an immediate turn to heading 360.The timing of this entire discussion; from lining up to wait until being cleared for takeoff; was about five minutes. Though I believe the FO and I took the time needed to discuss our options and develop a shared mental model before departing; I think I failed to recognize that the FO felt a little more pressure than necessary to make the initial turn quickly to avoid the weather. On takeoff we executed the precautionary takeoff profile and began our climbout. At approximately 250 feet. AAE (Above Aerodrome Elevation); the FO rolled crisply to 30 degrees of bank; making the turn to the north. Though I was a little surprised; it was clear that she was initiating the turn earlier than our procedural minimum altitude of 400 feet AAE. She clearly had control of the aircraft and we were climbing away quickly.Under the circumstances I elected to not intervene; believing that doing so could lead to confusion and distraction during a critical phase of flight. We continued our climbout uneventfully. On reaching our cruising altitude; I brought the departure turn up with the FO. She confided in me that she was so focused on the initial turn to avoid the weather that she mistakenly started it early. Like me; she realized it almost immediately but elected to continue the turn as the safest course of action under the circumstances. We both agreed that waiting the extra 150 feet in compliance with our standard operating procedures would have still kept us well clear of the weather. This event shows that even two crew members who are fairly familiar with each other and comfortable communicating can miss important cues. Looking back I could have done a better job at managing our pace. If I had just taken another 30 seconds to review our plan and talk the takeoff through; it may have either put the FO more at ease or clued me in that she still had some concerns about the decision to depart.




Synopsis: B737-700 Captain reported First Officer made an early turn; prior to altitude limit; on departure.