A strong storm off the East Coast of the United States produced a variety of winter weather over Maine on 13 February 2017, including Blizzard conditions. Although ceilings and visibilities above show IFR or near-IFR conditions at 1045 UTC, GOES-R IFR probabilities over Maine are small (less than 20%). Why?
The image below from this site shows Cloud Type, Low-Level Saturation, IFR Probability, and the Nighttime Microphysics. Both Ice clouds and falling snow are widespread over Maine. GOES-R IFR Probabilities typically assume saturation with respect to water. The Gray, ME morning sounding shows maximum RH (with respect to water) at only 94% (Link). Assuming saturation with respect to water rather than with respect to ice may be a source of error that will have to be investigated in the future.
Note that after sunrise, IFR Probabilities increased over Maine to values between 30 and 45% (Link).