Where conduct relevant to the offense (here, grounds for a sentence enhancement) is the subject of a contemporaneous prosecution in state court, the federal sentencing court must consider the Guidelines instruction that the terms are to run concurrently; there is no requirement that the state prosecution be on the docket at the time of federal sentencing.
http://www.ca2.uscourts.gov/decisions/isysquery/37d309e7-2938-46a7-887d-c286c9866ef7/1/doc/15-3449_opn.pdf#xml=http://www.ca2.uscourts.gov/decisions/isysquery/37d309e7-2938-46a7-887d-c286c9866ef7/1/hilite/
Since 2011. An occasional commonplacing of the U.S. Circuit Courts of Appeal.
Neither an authoritative statement of the law nor legal advice. Quick work.