B737 Next Generation Undifferentiated
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 175
Human-Machine Interface; Communication Breakdown
Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Provided Assistance; Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Airspace Structure; Human Factors; Weather
While descending into ZZZ; we were following another aircraft. We were slowed first; then vectored off course to create spacing. After there was enough spacing; we were cleared back onto the Arrival and to descend via. I put the fix in the box and selected LNAV. I rolled in our new altitude but forgot to select VNAV (Level Change was still selected). We continued to descend to our altitude via Level Change and went below the arrival altitudes. We entered clouds and when we got out of the bottom we both noticed we were low. As we tried to call ATC; they called us and we climbed to 5100 feet MSL. No alerts went off.The distraction was clouds/turbulence approaching. We were discussing our plan to coordinate with the Flight Attendants to clean the cabin and sit before the turbulence hit. We were issued our clearance during a time when we were also talking to the Flight Attendants. I entered our clearance but we failed to verify that VNAV was selected. It was error on both Pilot Flying and Monitoring. We were more concerned with Flight Attendant safety at that exact moment than verifying our automation.
[Report narrative contained no additional information.]
B737NG flight crew reported neglecting to select VNAV resulting in a descent below the arrival profile.