Date: 201911
Local time of day: 0601-1200
Location: ZNY.ARTCC, NY
Flight conditions: IMC
Weather elements / visibility: Thunderstorm
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Flight phase: Climb
Airspace: Class E ZNY
ATC / advisory: Center ZNY
Reporter organization: Air Carrier
Reporter function: Captain
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Human factors: Communication Breakdown
Second reporter function: Other / Unknown
Anomaly: ATC Issue All Types; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Requested ATC Assistance / Clarification; Flight Crew Returned To Clearance
Contributing factors: Procedure; Human Factors; Airspace Structure
Primary problem: Ambiguous

Narrative: On climb out of JFK; talking to New York Center; at 17;000 MSL cleared direct to COATE intersection; flight plan route; we noticed our track was going to take us through a very wide band of strong thunderstorms oriented north to south. Our weather radar was showing red returns with hatches that depicted areas where hail and lightning should be anticipated. We realized this was going to be a factor and attempted to alleviate the situation in a timely manner. Initially; we were still comfortably away from the storm and requested a climb. New York Center wasn't able to give us a higher altitude and told us it would be a second before we could climb. We advised the controller that we needed to deviate left of course for weather if we couldn't attempt to clear it vertically. The controller stated that he could give us right off course; however; he mentioned left deviation wasn't possible (no explanation why). Shortly after this transmission; we were cleared to climb from 17;000 to FL250. I expedited the climb as quickly as possible; unfortunately; the aircraft was heavy; engine anti-ice was on; and the temperature deviation was on the warm side. After comparing our climb to the weather radar returns we realized the storms were higher than expected (roughly FL350) and quickly assessed that we would not get on top of the cells. The controller's preference of deviating right off course was not an option to us because it would have taken us into a stronger cell and downwind of all the weather. As a result; flight plan route was closed out; right deviation was worse; and our only course of action was an immediate 90 degree left turn to a heading of 180. At this point; we were climbing through roughly FL220 with St. Elmo's Fire surrounding the aircraft; still not given a clearance to deviate the only way we thought was safe; and beginning to pick up precipitation and light to moderate turbulence (maybe 20 miles from the center of the cell). At this time we made a brief transmission to the controller that we needed a left turn. He asked; 'how far?' We had just initiated our turn during his call; but told him 90 degrees and that we had begun our turn to a heading of 180. While we were maneuvering the aircraft away from the weather and still climbing we obtained a frequency change and checked in with New York Center. It was after we felt the aircraft was in a safe and stable state that we discussed and eventually decided to inform the new controller that we operated under Captains Emergency Authority. The flight continued to an uneventful conclusion at our destination.


Second narrative: [Report narrative contained no additional information.]


Synopsis: Flight crew reported encountering thunderstorms on filed route during climb-out and the inability to obtain a revised clearance to avoid the storms.