Date: 201905
Local time of day: 1801-2400
Location: PHL.Airport, PA
Flight conditions: IMC
Weather elements / visibility: Rain; Thunderstorm
Light: Night
Aircraft: B737 Next Generation Undifferentiated
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Climb
Airspace: Class B PHL
ATC / advisory: TRACON PHL
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Human factors: Situational Awareness
Second reporter function: First Officer; Pilot Flying
Anomaly: Deviation - Speed All Types; Deviation - Track / Heading All Types; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight
Result: General None Reported / Taken
Contributing factors: Weather
Primary problem: Weather

Narrative: Highly dynamic and fluid scenario with ATC reroutes due to weather with time compression due to weather 20 miles west moving east at 40Kts. Taxiing out ATC stopped us for a reroute through Center airspace. By the time we got the clearance; loaded it into the FMC (Flight Management Computer); coordinated with Dispatch for release 2; and waited further for ATC to taxi us to the runway; the weather was very close to the western edge of [the airport]. An aircraft was cleared for takeoff along our same route; and we all waited for his PIREP (Pilot Report). He reported moderate turbulence. With the information we had; it appeared safe to takeoff. Our clearance was to fly heading 120 after takeoff. From the cockpit it appeared a safe course of action; so we accepted it. Our WSI was not being reliable due to internet problems; the TWIP (Terminal Weather Information for Pilots) we requested came too late; but the PIREP seemed as if it may be just a little bumpy; nothing more than moderate. The problem occurred when we rolled out on the 120 heading; unbeknown to us the weather had passed the airport to the east and south and was a wall of red staring us into the face. The takeoff up to 3800 feet was in the clear; smooth; and uneventful; but above 3800 feet we entered the weather and the moderate turbulence. ATC gave us direct SBY; which would also put us into more weather. Luckily we found a hole somewhere around a 180 heading; which we picked up with ATC's approval. But between the 120 heading and finding the hole; the ride deteriorated considerable. At approximately 6000-8000 feet we entered severe turbulence; which lasted until around 12000 feet; as we finally found the hole. We probably had about two encounters of severe [turbulence] in that period. The parameters ranged with momentary deviations as follows: Pitch from 5-20 degrees nose up; airspeed from 200-250 knots approximately; and roll from +/-15 degrees from commanded (Bank angle warning sounded twice but roll never exceeded 40 by our estimation). We did not think the aircraft was ever uncontrollable or out of control; but the deviations were excessive and the pilot workload was substantial. Fortunately there were no injuries reported and all passengers and flight attendants were in their seats with their seat belts fastened. The FA's (flight attendants) had been briefed to remain in their jump seats until we called them after the climb out when it would be safe. We recommended to ATC; after reporting severe turbulence; not to allow anyone else to takeoff in our direction; as it was no longer safe to do so.


Second narrative: We took off Runway XXL and did an immediate left turn to heading 120 to avoid thunderstorms that were 3-5 miles from airport. Preceding aircraft reported moderate turbulence. I believe FA's (flight attendants) were told to remain seated after takeoff until we contacted them. On climb out we experienced severe turbulence between 5000ft and 10000ft. Pitch fluctuated between 0 to 20 degrees; roll plus or minus 15; airspeed 200-250kts. After we exited the turbulence we told ATC that we would not recommend the route to next aircraft. We advised Dispatch and Maintenance of the event en-route then debriefed Maintenance once at [the destination].


Synopsis: B737 flight crew reported encountering severe weather during climb after takeoff.