Mortgage interest rates rose again this week, marking the fourth consecutive increase. Freddie Mac says the average rate on a 30-year fixed mortgage has jumped to 4.61 percent, up from 4.46 percent just one week earlier. If such sharp increments continue at this pace, the 30-year rate could rise above where it was a full year ago (4.81 percent) in a matter of mere weeks. For a $200,000 conventional loan, the sudden rise amounts to $50 more in monthly payments than if buyers had locked in rates just two months ago.