Seasonal adjustments to the CS-HPI

In response to an email request that asked the question of how current seasonal adjustments compare to past seasonal adjustments for this time of year for the 20-City Case-Shiller Home Price Index, the following chart was promptly whipped up.
The scale on the left is simply the difference between the seasonally adjusted monthly change and the unadjusted figure, so, in the case of December, +0.3 percent minus -0.2 percent (as noted in the last post) results in about +0.5, which looks to be low, if anything.

Seasonal adjustments peak in January and given the fact that the precise data was not yet available when this chart was prepared, there's a built-in margin of error of +/-0.1, so, the most recent adjustment could actually be a bit higher, more in line with prior years.