I noticed in St. Louis on I-44 a MoDot sign warning truckers of "extreme delays in West Memphis on I55." That made me think what I was seeing on the METAR map was due to persistent ice in Arkansas and Mississippi. When the equipment is not functioning, the dot on the METAR is shown as red.
However, after clicking on some of them, the red does appear to be caused by true IFR conditions.
I wonder how "weather proof" the METAR reporting stations are? If there is a severe ice storm, but the next day the weather itself is VFR, with the station be able to report despite the ice?