In case you don't feel like tracking down my post from last January, here's the synopsis from the performance detail page.
Making his BSO subscription series debut, conductor John Storgårds leads pianist Martin Helmchen in Mozart's gregarious, large-scale Piano Concerto in E-flat, K.482, composed in late 1785 when Mozart was also working on his comic opera The Marriage of Figaro. The Finnish Storgårds also brings three Finnish works to Symphony Hall, beginning with Kaija Saariaho's gorgeous study of orchestral color Ciel d'hiver ("Winter Sky"), an arrangement of a movement from her earlier, symphony-like Orion. Jean Sibelius's final two symphonies, nos. 6 and 7, are two of the greatest works in the symphonic literature. Though very different from one another, both demonstrate the composer's distinctively rich orchestration and organic, fluid transformations of material.(Some emphasis added.)
As always, you can hear it all on air or over the web on WCRB at 8:00 p.m. EST. They also have links to features about this concert and other broadcasts they offer.