"why does this always seem to rise into the close? short covering? any ideas?"
I have a simple explanation in the old addage...the smart money buys at the end of the day, not at start. The recent change I suspect/hope is institutional funds jumping in. IBD has A+ Accumulation/Distribution rating and 1.8 Up/Down volume indicating very bullish environment.
Perhaps for one time Cramer is pumping a stock at the beginning of its run rather than top!
Actually 180M short is not much. Maybe a little over 2 days volume. I still am convinced that the daily PPS movement is accumulation. Stock is moving on fundamentals and very positive future indicators.