Citationjet (C525/C526) - CJ I / II / III / IV
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 10
Situational Awareness; Workload
ATC Issue All Types; Conflict NMAC; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Issued New Clearance
Human Factors; Weather
I was the Radar Controller working combined sectors. Aircraft X was climbing out westbound; and contacted us for further climb. I am not 100% sure if I issued a climb on initial contact to 26;000 feet. or not. It is possible that it fell through the cracks; as I was busy at the time. Aircraft X called to ask if there was traffic at their 12'oclock; at which time I noticed a data tag in the adjacent TRACON's airspace at 23;000 feet.; the same altitude as Aircraft X. Without coordination; I instructed Aircraft X to immediately turn to a 180 heading and expedite a climb to 26;000 feet. There was absolutely a Loss (of Separation) and probably a NMAC. My d-side (Assist) called the TRACON to advise them that we had turned Aircraft X. I am not sure with whom the fault lies; as I cannot be 100% sure that I issued a climb on initial contact; and I am not sure how long Aircraft X was level at 23;000 feet. The LOSS occurred in TRACON airspace. This partially stems from the sector being overloaded with weather and traffic; and partially from controller error (assuming the climb was not issued). I feel that more attention needs to be given to sectors that are experiencing high volume and weather; and better staffing procedures should be implemented. It is a known issue that the TSD (Traffic Situation Display) numbers do not function correctly at this sector; and thus it does not receive the management and Traffic M(Management) Unit support that it often deserves.
ZJX Center Controller reported they may have caused a loss of separation and an NMAC in the adjacent TRACON airspace.