With a residential tower in Surfside, Fla., reduced to a smoking heap of debris several stories high, and families near the site holding onto slim hopes of their loved ones’ rescue, Rabbi Joseph Potasnik found himself revisiting the trauma of September 11, 2001, when he was the Jewish chaplain for the New York City Fire Department. For months afterward, Potasnik tended to the families of the missing and to a recovery crew whose members were among the mourners. The feelings of hope, dread, heartbreak and solidarity at Ground Zero never left him. Potasnik was already anticipating the practical and spiritual challenges first responders, families and clergy will face in the days ahead. On Tuesday, on a conference call with their South Florida counterparts, he and several other rabbis from New York will be able to share their wisdom.