Never flown the RJ, but I doubt a 146 could. ISA+20 at 2500AMSL being about 30C would be too hot I would say off such a short runway.
The 146 is flat rated to only 15C, the RJ is higher, but not sure what the figure is, so it should be a bit more spritely. Also, as 146/RJ's all share the same engine, regardless of variant, the 70 should perform that bit better, being a bit lighter.
The ALF engines run out of steam very quickly as the temperature and/or altitude rises, so, while they can get good loads off limited runways, you can't expect miracles.