GOES-R IFR Probabilities from GOES-West and surface observations (Upper Left), Brightness Temperature Difference (Upper Right), Topography (Lower Left), MSAS-derived dewpoint depression and surface observations (Lower Right)

Detection of fog and low stratus in Alaska present some unique challenges related both to the very low sun angle that is common there, and the large GOES-West pixel size.  Nevertheless, the fused product does give important information in a state where small planes are ubiquitous for transport between towns.  The loop above shows the development of IFR conditions within the Yukon River valley in east-central Alaska;  note the reduction in visibility that occurs at Fort Yukon (and only there) as the IFR probabilities increase.  IFR probabilities also increase in the Yukon Territory of Canada.  The lack of surface observations there highlights another challenge in Alaska:  Verification of predictions of IFR conditions.