From Bloomberg News:
In response to a question about what data the Fed might look for before it adjusts its path, Yellen answered, "Inflation data is very noisy, month-to-month, hopefully this isn’t too much in the weeds -- but there is residual seasonality in inflation and inflation data, which will tend to result in lower inflation readings” in the second half of the year.
It could be interesting if we see that trotted out a reason to look through soft readings (if there are soft readings) going forward.
From a footnote to Yellen's speech:
In general, price changes measured over a few months tend to be noisy, even when measured on a core or trimmed-mean basis. For this reason, the FOMC usually focuses on the growth rate of PCE prices over the previous 12 months, which smooths through the volatility in the monthly price data. This approach also sidesteps distortions in the monthly data associated with residual seasonality; these distortions are likely to hold down month-to-month changes in prices over the balance of the year (see Peneva, 2014). That said, 12‑month rates of inflation will continue to be held down through early 2018 by the unusually weak monthly readings on price changes recorded in early 2017.