Billings WFO here. We have an odd circular temp/RH/Td anomaly showing
up in our URMA grids, and thus getting into NBM grids. It's in
northern Rosebud county (north of Forsyth) and is in an area w/o any
observations. I have attached an URMA MinRH image from March 2nd. As
you can see it really stands out (it's actually donut-shaped). There
is no terrain in that area that would cause such a shape of cooler
temps, higher Tds, higher RHs. There is a MT-MESO station (Ingomar
NE) that is west of the donut, and I thought maybe it had an impact,
but that station hasn't reported since Feb 4th. Thoughts? I should
also mention, this is a fairly new artifact. I noticed it perhaps a
couple months ago. It could have coincided w/ version 4.0. Thanks for
your help!