Below is the link to the stockcharts.com's daily chart on PRB. The above little RSI chart would indicate support at the .50 area, we're near to it at the moment. The main chart's action would indicate that the 1.80 to 1.83 area is expected support if weakness continues provided by the 50 day average. The lower MACD which looked to be turning up was nudged lower this morning which continues down but with little threat of any meaningful weakness continuing.

http://stockcharts.com/h-sc/ui?s=prb.v