Early this morning my system picked up the following ADS-B traffic:

601831 TUG3700 EZ-A700 B737 at 22-04-20 03:30:49 UTC

601831 EZ-A700 TUG3700 0.00000 0.00000 38000′ 303.2∞ 447.1kts 03:38:58UTC 6 *g B737 3250 1 A3

It turns out to be the personal aircraft of the president of Turkmenistan. A bit of an illusive aircraft because not many details are known. However a fellow PP pointed me in the direction of an interesting article:

Boeing 737 EZ-A700 (translated). The original article (including imagery) can be found here.

A rare image of the actual airplane can be found here.

The aircraft apparently landed at KADM this same day after a stop over at probably KPQI. The reason for the aircraft being at the destination is probably for maintenance or upgrades / alterations to systems or the interior.