Economist Nouriel Roubini, perhaps better known by some as “Dr. Doom” for his accurate forecast of the recent economic downturn, tweeted to more than 20,000 followers Wednesday that the chances of a double-dip recession have reached more than 40 percent. The Twitter revelation set off waves, and yesterday Roubini called in to CNBC to expound on his eerie prediction. He said he believes the economy grew at an even slower pace than previously reported during the second quarter. And because economic boosters like temporary jobs added for census workers and homebuyer tax credits will disappear, he said, GDP growth in the third quarter is likely to be closer to 0 percent than 1 percent, which would indicate a double-dip.