The analysts at Wisonsin-based Fiserv, Inc. are forecasting average U.S. home prices to fall by another 2.7 percent through the third quarter of 2012, before rising 3.8 percent by the third quarter of 2013.

The company says the monthly mortgage payment for the median-priced U.S. home has dropped to $640, nearly 45 percent below the housing bubble peak of $1,150 and its lowest level since 1994. Mortgage payments now account for only 14 percent of monthly median family income, according to David Stiff, Fiserv’s chief economist.

This improvement in housing affordability is expected to drive sales activity going forward, and while not enough to change Fiserv’s predictions for the direction of home prices at the national level, the company does foresee notable improvements in select markets.

Stiff notes that while prices continued to fall in most markets, sales activity picked up at the end of 2011, setting the foundation for price stabilization in 2012.

Stiff also cited the impact of improving economic indicators, such as consumer confidence, which while still extremely low, has bounced back from its sharp decline following the downgrade of U.S. debt.

He stressed that if the job market continues to improve, then the rebound in consumer confidence will be sustained this year and more households will be willing to purchase big ticket items such as a house.

“[W]e do anticipate that increasing sales activity will begin to drive small increases in prices in as many as half of U.S. metro areas,” Stiff said.

He says some larger metros that escaped the worst of the home price bubble, such as Houston and Fort Worth, Texas, as well as Salt Lake City, Utah, can expect increases of 1 to 3 percent in the coming year. Many smaller metro areas, such as Boise, Idaho, and Albuquerque, New Mexico, are forecast to see increases of 4 to 6 percent.

In addition, between Q3 2011 and Q3 2012, prices are projected to rise by at least 5 percent in seven metro areas: Gainesville, Georgia; Sumter, South Carolina; Lake Havasu City-Kingman, Arizona; Pueblo, Colorado; Coeur d’Alene, Idaho; Bremerton-Silverdale, Washington; and Madera, California.

The latest home price data from Fiserv shows that the average price of a U.S. single-family home fell to a new post-bubble low in the third quarter of 2011, declining 3.9 percent compared to the year-ago period.

The company reports that current average home prices are now 33 percent below the 2006 peak. Over the past year, home prices fell in 337 of the 384 metro areas tracked by Fiserv’s Case-Shiller index.

Despite continued price erosion, Fiserv says some metro areas saw significant home price gains in the past year including markets that were deeply affected by the housing bubble and recession. Examples include Detroit, Michigan (11.1 percent), Buffalo, New York (6.7 percent), and Fort Myers, Florida (2.8 percent).

California and Florida, two of the states hit hardest by the housing market bubble, account for 10 of the 20 metro areas forecast by Fiserv to see the greatest increase in home prices through 2016.