Mostly Colorado blue skies will soon fade with radar on Grand Mesa showing invading clouds on the Utah border as I write this forecast at 07:30. A powerful storm system birthed in the Pacific Northwest is riding up and over the Serria today and will close off into low pressure system in the Great Basin this afternoon. As the low deepens and builds it will drop into the 4-corners bringing showers and thunder snow this afternoon into the southern San Juan Mountains with warm temps in place in the lower elevation then gradually turning to snow above 9,000′ tonight with cooling temps.
Models are not in agreement with the forecast but do show prevalent convective storms that will precipitate with vigor wherever the convective cells/bands form but exact locations are impossible to forecast. A warm atmosphere in the lower elevations early today put rain/sleet below 8,000′ and initial snow levels above that #. This system should bring good storm totals depending on your location but we should see between 10-14″ on southwest facing terrain above 10,000′ with the potential of 2′ or more in those secret and favored locations. These pinched off 4-corner lows (happening Friday-see pressure/precip map below) can wobble around and create good precipitation rates over a long period of time.
Three models have this storm system affecting the San Juans through Saturday with precipitation diminishing from NW to SE through the day. A brief ridge of high pressure builds Sunday then the next storm of this progressive spring pattern should arrive Monday evening and last through Tuesday then clearing beginning Wednesday.