Yeah the GFS not only has problems with handling shallow cold air mass extent, but also usually underestimates the depth of said air mass.
The GFS is actually doing exactly that over me as we speak as this backdoor cold front moves across southern NM.
If we can overcome the deep sub-cloud dry layer here in NM, isentropic upglide and warm advection will favor some light snow showers overnight into early tomorrow before a bigger shot of mid-level warm advection moves in tomorrow afternoon.
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View attachment 160993