Too bad they can't fix the freezing fog from icing over the temperature sensor. It's happened twice now this winter on the KVTN ASOS. As it ices over, it warms. Why because it blankets the sensor in thick ice like it does everything else. They really need to go back to a naturally aspirated Stevenson Screen with a fan like they use in Canada, and other countries. At least you can turn the fan off to prevent the sensor from becoming ice covered.
What happens is the RH goes up with the temperature separation (air and dew point), as you can see here. The actual air temperature was near the dew point temp (12°) with the thick ice fog. The dew point sensor is separate and non-aspirated, so was the only true indicator of temperature, with the near zero visibility at times.
NOAA just gave a contract to RM Young for their aspirated shield, another mistake. The RM Young is famous for sucking in heated exhaust during light wind and reading high, along with other issues. Just ask Jerry Graves he has one. They really should have considered the naturally aspirated baranidesign gen3 MeteoShield's as shield replacements. They follow the Stevenson Screen with a fan very closely, with extensive testing done by University of Vienna.