The Dallas Fed is looking for juniors who would make strong applicants.( https://frb.taleo.net/careersection/2/jobdetail.ftl?job=261545&lang=en)
The Fed is looking for students with a good math and econ background (Calc I, II, III, Linear Algebra, Real Analysis, Econometrics I & II, Advance Micro and Macro, Advanced Stats, maybe grad level econ), good coding skills (R, Python, Stata, Matlab), and RA experience.