The 21-year-old back row has been cited for a dangerous tackle following the 17-16 defeat at Parc y Scarlets last Friday.
Turnbull, who has made three Magners League appearances for the Scarlets so far this season and 12 in total, will appear before a disciplinary hearing on Wednesday evening.
The hearing will take place at the Millennium Stadium in Cardiff under the jurisdiction of the Welsh Rugby Union Disciplinary Panel, with the result expected to be known that that night.
Turnbull was yellow carded for a tackle on Edinburgh centre Nick de Luca during the second half of a tight contest but could now face further punishment.
If found guilty, he could miss the Scarlets' Magners League clashes with the Ospreys and the Dragons over the festive period, as well as their back-to-back European games against Leinster this weekend and next.
After taking on the European Champions in the Heineken Cup on successive matchdays, the Scarlets host the Ospreys in the Magners League on Boxing Day before travelling to Rodney Parade on New Year's Eve, followed by a trip to Munster on January 10.
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