CNNMoney.com recently published its 2010 forecast and projections for home prices in the country’s largest metro markets.

Listed as “Top 25″ and also comprehensively by state, CNNMoney.com’s home price forecasts puts Santa Rosa, California at the top of 2010′s home appreciation list and Hanford, California at its bottom.

The 10 cities projected for highest home appreciation in 2010 are:

1. Santa Rosa, CA : +6.0%
2. Cheyenne, WY : +4.7%
3. Kennewick, WA : +4.6%
4. Merced, CA : +4.4%
5. Bremerton, WA : +4.2%
6. Fairbanks, AK : +4.2%
7. Corvallis, OR : +4.1%
8. Tacoma, WA : +3.9%
9. Anchorage, AK : +3.8%
10. Bend, OR : +3.3%

The Pacific Northwest is the region most heavily-represented among price gainers. The Southeast and Middle Atlantic are most represented on the under-perform list.

However, just because a city’s homes are expected to appreciate (or depreciate) in 2010, that doesn’t mean that every home within its limits will follow suit.  Real estate cannot be grouped on a city level like CNNMoney.com tries to. There will always be areas in demand within city limits in which prices rise, just as there will be out-of-demand areas in which prices fall.

Real estate data can’t be grouped by city or even by ZIP code, really.  It’s more local than a city, more local than a ZIP code, and certainly more local than an MLS area.

When we say “real estate is local”,  it means that every street in every town has a distinct set of traits that drives its home values. Homes that are one block closer to the train; or, homes that are facing north; or, homes that are made of brick. Each of these characteristics can affect a home’s desirability which, in turn, can affects its sales price.

National surveys can’t capture “essence” like this. They only report on the aggregate.

For local real estate data, look to established, publicly available websites and to active, local real estate agents.  Both will have data and insight that can help you.  National surveys often make for good headlines, but do little to help homebuyers find good value.

Earlier this week, the private-sector Case-Shiller Index showed home prices slightly lower between November and December.  Thursday, the public-sector Home Price Index showed the same.

Publishing on a 2-month lag, the Federal Home Finance Agency said home prices fell by 1.6 percent nationally in December.  And that’s an average, of course.  Some regions performed well in December as compared to November, others didn’t.

• Values in the Middle Atlantic states improved slightly
• Values in New England were essentially unchanged
• Values in the Mountain states sagged, down 3.5%

These aren’t just footnotes. They’re an important piece toward understanding what national real estate statistics really mean. In short, “national statistics” are just a compilation of a bunch of local statistics.

For example, if we dig deeper into the FHFA Home Price Index 70-page report, we find that cities like Terre Haute, IN, Buffalo, NY, and Amarillo, TX posted year-over-year home price gains. You won’t see that in a “national” report.

Furthermore, it’s a sure bet that those same cities, you could find neighborhoods that are thriving, and others that are not.  Just because the city shows higher home values overall, it won’t necessarily be the case for every home in the city.

Every street in every neighborhood of every town in America has its own “local real estate market” and, in the end, that’s what should be most important to today’s buyers and sellers.  National data helps identify trends and shape government policy but, to the layperson, it’s somewhat irrelevant.

So, when you need to know whether your home in Oak Park is gaining or losing value, you can’t look at the national data.  You have to look at your block — what’s selling and not selling — and start your valuations from there.

The Case-Shiller Index was released on Tuesday.  It revealed only a 2.5% drop in home values, significantly better than the 8.7% drop reported after 2009 Q3.

According to Case-Shiller representatives, we’re seeing a healthier market than one year ago.  We’re also seeing that the market is returning to a normal healthy rate of recovery after last summer’s incredibly hot market.

Of note, 5 markets didn’t decline:  Detroit, Los Angeles, Las Vegas, Phoenix and San Diego.

They were the hardest hit in the beginning and are now showing the first signs of strength as the market returns.

The Case-Shiller Index isn’t without flaws.  For example:

1. The data is two months old
2. It is only 20 cities
3. Real estate is local, not national

Still, the index carries weight as the broadest private-sector index out there.  Housing is key to the economic recovery and we’re seeing good signs in housing.

Home prices ticked up 0.7% in November.  The Federal Housing Finance Agency tracks this data and, like Case-Shiller, it runs on a two-month delay.

That is perhaps the biggest issue.  The Realtor data shows 80% of Pending Home Sales close within 60 days meaning that the home price figures are always about a full sales cycle behind.

Over a year, the data can be fairly useful.  The facts are that home prices are up and home supplies are down over the past 12 month.

There are three main reasons to buy a home today:

1. First time home buyer tax credit
2. Home prices are low
3. Mortgage rates are low

We’re inside of 90 days on the expiration of the tax credit, we’re already seeing home prices move higher, and FHA interest rates are going to rise at the termination of the Fed’s purchase program.

Homes may not be this affordable for quite some time.