Wondering if I could build pitched frame to act as a roof with a tarp, so snow would slid off.. that is my main concern is the weight of the snow. Thanks for any suggestion or pictures

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If you put wire fencing (welded wire or hardware cloth) over the frame, it will help support the tarp and reduce sagging.
Or you can use cattle panels to make arches, although they usually have big enough holes that the tarp will sag a bit through the holes. You could cover a cattle panel with hardware cloth, and that will keep the tarp smooth enough for rain to run off nicely.
No matter how you support it, you will probably have shovel or sweep off the snow after it falls, and of course be careful not to tear up your tarp while doing it. If the tarp gets a few small holes, it will still keep out most snow, but holes tend to rapidly get bigger once they start.
Depending on the size of your run, you could put some sturdy boards across (2x4 or larger, skinny side up), and then put sheets of plywood on top. You would still have to shovel after each snowfall to keep it from getting too deep and heavy.
I don't know how fast your snow usually falls, so I don't know whether removing the snow each morning is enough with any of these, or if you'd have to go out a few extra times to keep it from getting too heavy and collapsing.