The U.S. economy is on track for "solid growth" in the second quarter after a sharp slowdown over the winter, U.S. Federal Reserve (Fed) Chair Janet Yellen said Wednesday. In mostly optimistic testimony to the Joint Economic Committee of both chambers of Congress, Yellen said the stalling of growth in the January-March period resulted from mostly transitory factors, "including the effects of the unusually cold and snowy winter weather." "With the harsh winter weather behind us, many recent indicators suggest that a rebound in spending and production is already underway," the Fed chief told lawmakers. Yellen said she expects economic activity to expand "somewhat faster" this year than in 2013, helped by less political fighting in Washington over government spending, improved household wealth, and stronger global economic growth. However, while labor-market conditions have improved "appreciably," the central-bank chief said they "are still far from satisfactory." Repeating a concern she has expressed since becoming Fed chief in February, she emphasized the high levels of long-term unemployed people and those forced to work part-time because full-time positions are not available.