def selectUTMZone(self, longitude, latitude):
        '''
        return UTM/UPS Zone spatial reference based on longitude and latitude
        * Datum is GCS_WGS_1984

        Based on gis.stackexchange.com referenced on 1/24/2017:
        http://gis.stackexchange.com/questions/13291/computing-utm-zone-from-lat-long-point

        Inputs:
        longitude: latitude (assume GCS WGS 1984) of UTM zone
        latitude: longitude (assume GCS WGS 1984) of UTM zone

        Output:
        targetSpatialReference: Spatial Reference object of UTM zone of input lon/lat.

        '''
        try:
            targetSpatialReference = None
            if latitude > 84.0:
                arcpy.AddMessage("Area above 84.0 degrees within North polar zone. Using Universal Polar Stereographic North projection.")
                srName = "UPS North"
            elif latitude < -80.0:
                arcpy.AddMessage("Area below -80.0 degrees within South polar zone. Using Universal Polar Stereographic South projection.")
                srName = "UPS South"
            else:
                z = None
                hemisphere = "N"
                if latitude < 0.0:
                    hemisphere = "S"

                if (latitude >= 56.0 and latitude < 64.0 and longitude >= 3.0 and longitude < 12.0):
                    z = 32
                elif (latitude >= 72.0 and latitude < 84.0):
                    if (longitude >= 0.0 and longitude < 9.0):
                        z = 31
                    elif (longitude >= 9.0 and longitude < 21.0):
                        z = 33
                    elif (longitude >= 21.0 and longitude < 33.0):
                        z = 35
                    elif (longitude >= 33.0 and longitude < 42.0):
                        z = 37
                else:
                    z = int(math.floor((longitude + 180.0)/6.0) + 1)
                srName = "WGS 1984 UTM Zone {0}{1}".format(z, hemisphere)

            arcpy.AddMessage("Using {0} for {1},{2}.".format(srName, longitude, latitude))
            targetSpatialReference = arcpy.SpatialReference(srName)
            return targetSpatialReference

        except:
            tb = sys.exc_info()[2]
            tbinfo = traceback.format_tb(tb)[0]
            pymsg = "PYTHON ERRORS:\nTraceback info:\n" + tbinfo + "\nError Info:\n" + str(sys.exc_info()[1])
            msgs = "ArcPy ERRORS:\n" + arcpy.GetMessages() + "\n"
            err = "{0}\n{1}".format(pymsg, msgs)
            raise Exception(err)