Cooling home price appreciation and growing wages may seem like good signs for house hunters, but home affordability still plunged to a more than 10-year low, according to Attom Data Solutions.Nationwide, Attom's Home Affordability Index flopped to a reading of 91 in the fourth quarter, down 15% from a year ago and the lowest level since the third quarter of 2008. An index value under 100 indicates home prices are less affordable than the historic average, according to Attom.What's more, many local markets are faring even worse than the national landscape. While it's true that many markets are seeing a slowing of home price gains as available inventory becomes more plentiful, many cities are treading close to housing bubble territory as price appreciation continues to outpace local wage growth.With home affordability at a 10-year low across the nation, here's a look at the 12 cities most in danger of a housing bubble in 2019. The analysis, based on Attom data, evaluates counties with a minimum population of 100,000, at least 100 quarterly home sales and a median sales price above the national rate of $241,250. Counties are ranked by the gap between the annual increase in home prices and wages. Ties were broken by the lowest Affordability Index Value.