Weekly mortgage applications jump unexpectedly

A sign offering mortgage help at a Bank of America branch, New York City.
Scott Mlyn | CNBC
A sign offering mortgage help at a Bank of America branch, New York City.

Despite a relatively quiet week for interest rates, mortgage applications took an unexpected jump.

Total application volume rose 4.9 percent week-to-week for the week ending November 14th, according to the Mortgage Bankers Association (MBA). The week's results were adjusted for both seasonal trends and for the Veterans Day holiday.

The increase was driven almost entirely by applications to purchase a home – a turnaround from recent months. While refinance applications rose just one percent week to week, purchase applications leapt 12 percent to the highest level since July.

"MBA and other data are showing strength in the market for new homes, likely reflecting the boost from continued job growth in recent months," said Michael Fratantoni, chief economist for the MBA.

Mortgage applications are an indicator of future home sales, as consumers must secure the loan before closing on a property. Home builder sentiment rose in November, with the builders citing an increase in buyer traffic, according to a report Tuesday from the National Association of Home Builders.

Read MoreHome builder confidence jumps 4 points in November

Purchase applications are still running 6 percent below year-ago levels, and they are 9 percent lower than they were four weeks ago, on a non-seasonally adjusted basis.

"This is historically a volatile time of year for purchase applications, and MBA's seasonal adjustments made the difference," said Matthew Graham of Mortgage News Daily, noting that purchase applications were actually down 3 percent week to week unadjusted.

Whatever the adjustments or volatility, purchase application volume is anemic compared with historical norms. This smaller volume makes percentage moves up and down larger than they might normally be. This week's jump is certainly welcome for the housing recovery, but the trend needs to continue long-term to make a dent in the weakness.

Read MoreFederal Housing Administration back in the black

The average contract interest rate for 30-year fixed-rate mortgages with conforming loan balances ($417,000 or less) decreased to 4.18 percent from 4.19 percent last week, according to the MBA. This week rates are edging slightly lower, with some of the best borrowers now getting quotes in the three percent range again.