Mortgage rates hadn't changed much over the past few business days, even though they arguably should have moved a bit higher yesterday.  That made today's adjustment slightly more abrupt.  Why was there an adjustment?

Mortgage rates are based primarily on the trading levels in the bond market.  In turn, the bond market takes cues from a multitude of factors big and small.  Among the biggest considerations for bonds are the various regularly scheduled economic reports.  Among those reports, inflation data is traditionally very important to bonds.  And finally, among inflation data, today's Consumer Price Index is probably the most widely followed.
Inflation didn't jump in any major way, but the important "core" reading (which factors out food and energy) was slightly higher than expected on an annual basis.  In general, higher-than-expected inflation puts upwardpressure on rates, and that was part of the problem today.  Rates also responded to the increased likelihood that there would not be another government shutdown at the end of this week (based on clues gleaned during a White House press conference early this morning).

All of the above (plus some additional esoteric factors) pushed rates to their highest levels since February 5th.  That said, the days between now and then have seen some of the best rates in more than a year.  Compared to most everything that came before then, today's rates are still right in line with those 1-year lows.

Tomorrow brings more important economic data in the form of the Retail Sales Report.  We haven't seen this data since the government shutdown began in late December.  It's unclear whether investors will be interested in reacting to this report in a major way, but it's a risk to be aware of heading into tomorrow.  If the numbers are stronger than expected, rates could continue higher, but if it's much weaker than forecast, we could edge back down to recent lows.