Larry Dighera wrote:

The plane disappeared from the radar screen of the Federal
Aviation Administration's facility at Warrenton around 11:40 p.m.

Observed weather at the time:

http://weather.noaa.gov/weather/current/KRMN.html
Time Temp F(C) DPoint F(C) Press In(hPa) Wind MPH Weath
EST (UTC)

2 AM (7) Feb 23 41 (5) 37 (3) 29.89 (1012) Calm fog
1 AM (6) Feb 23 41 (5) 37 (3) 29.92 (1013) Calm fog
Midnight (5) Feb 23 41 (5) 37 (3) 29.94 (1013) Calm drizzle
11 PM (4) Feb 22 41 (5) 37 (3) 29.95 (1014) Calm light drizzle
10 PM (3) Feb 22 41 (5) 37 (3) 29.98 (1015) Calm mist

The visibility was pretty crappy in the vincinity. At Dulles
at the same time we had 1/16 mile visibility and ceiling to
the ground. Many of the other awos's were reporting similar
(below ILS minimums) in the area. RIC and some of the airports
to the south were much better (light rain, but visibilities around
6 miles).