GFS 500 MB Forecast. Valid At 5 PM MST Saturday, Dec 3, 2016. GFS Surface Map & Precipitation Type Forecast. Valid At 5 AM MST Saturday, Dec 3, 2016. Valid At 5 AM MST Sunday, Dec 4, 2016. GFS Storm Total Rainfall Forecast. Valid At 5 PM MST Sunday, Dec 4, 2016. GFS Snowfall Accumulation Forecast. Valid At 5 PM MST Sunday, Dec 4, 2016. A strong backdoor cold front will work its way southward and westward into the eastern plains of New Mexico Thursday afternoon and evening. This front will arrive in southeastern New Mexico late Thursday night or early Friday morning. Colder and wetter conditions will follow the frontal passage. Meanwhile a strong upper level storm will dive into northwestern Mexico tomorrow afternoon. This storm will form a cutoff upper level low that should be located over the central Baja, Mexico Region by Saturday evening. Model forecasts have it opening up and ejecting northeastward into West Texas by nex...