For August, the Case-Shiller Index showed annual home values improving across 19 of 20 U.S. markets. It’s the first time in 3-plus years that the benchmark housing index has shown such strength.

According to a Case-Shiller Index spokesperson, “The rate of annual decline in home price values continues to improve.”

It’s yet another sign that housing may have already bottomed.

However, just because the Case-Shiller Index shows a stabilization in home values, that doesn’t necessarily make it true. This is because real estate happens on the local level and the Case-Shiller Index is more “national”. It tracks data in just 20 U.S. cities.

Homeowners everywhere else are unaccounted for.

Furthermore, even within the 20 tracked Case-Shiller markets, there’s no allowance for the natural sub-markets that exist. Some neighborhoods under-perform and some neighborhoods out-perform.

Case-Shiller treats them all the same.

Despite its imperfections, though, the Case-Shiller Index remains a helpful, broader measurement of U.S. real estate. Economists believe that housing led the U.S. into the recession and they believe housing will lead us out, too.

If that’s true, August’s Case-Shiller data is another step in the right direction.

For the second month in a row, 18 of the 20 Case-Shiller real estate markets posted higher home values.  It’s the 6th consecutive strong showing for the benchmark private-sector housing index.

Combined with falling home supplies and rising sales figures, this month’s Case-Shiller Index suggests that housing may have bottomed sometime earlier this year.

It’s cause for optimism.

Even Case-Shiller respresentatives seem excited. In its press release, the publishers singled out the index’s winning streak, commenting on the recent “stabilization in national real estate values”.

But, in that statement, we see the Case-Shiller Index’s biggest flaw.  The index ipurports itself to be a national real estate metric but, in reality, there is no such thing as a national real estate market.

All real estate is local. I will be posting reports for the North Georgia Mountain Real Estate market within the coming days. These reports will include data from Blue Ridge, GA . in Fannin County, Ellijay in Gilmer County, as well as Blairsville in Union County and Hiawassee in Towns County. These Real Estate Market Reports will be for both vacant lots and acreage sales, as well as residential.

The Case-Shiller Index reports home values for 20 U.S. cities.  Each of those cities, however, is comprised of smaller neighborhoods, each with its own character, desirability, and price points.  Case-Shiller attempts to lump it all together — an impossibility.

As an example, New York City posted a nearly 1 percent increase in July but that figure is just a city summary.  The actual market in three distinct neighborhoods — Upper East Side, Chelsea, and Flatbush — vary tremendously.  Not to mention Long Island, too.

Flaws aside, though, Case-Shiller is still important.  It helps to identify broader trends in housing and housing may hold the key to our economic future.

With July’s Case-Shiller Index, we see that the housing market’s recovery is being sustained.

At the start of the year, the “experts” made a lot of predictions about the U.S. economy and what to expect in 2009. 

• Some said housing would rise
• Some said housing would fall
• Some said mortgage rates would rise
• Some said mortgage rates would fall

And nobody predicted just how big the government’s stimulus package would be.

Now, on June 30, with the year officially half-over, it’s as good a time as any to remember that people are much better at interpreting the past than predicting the future.  Economists can make educated guesses about the future, but they’re guesses nonetheless. 

It’s like watching the Weather Channel.  A meterologist can look at the data and say it’s going to rain next week, but the forecast is never 100%.

So far this year, mortgage rates have been up and down, credit availability has been higher and lower, and home prices have varied immensely from neighborhood to neighborhood. 

There’s another 6 months until 2010 and there’s no reason to expect the current volatility and uncertainty to change. 

The world is unpredictable and so is the U.S. economy.  Therefore, consider making your personal finance decisions based on the information at hand today instead of on an educated guess about the future.

After all, the weatherman’s been wrong before.