I've been Googling and research somewhat confirms what I have already experienced and that is that 900MHz is not a good choice in snow country.
I have noted a marked decrease in 800MHz signals during moderate to heavy snow storms. The ski resort where our HF station was to place a HF rig (at 8,000 feet) uses 900MHz and its performance is poor. Further reading shows that 2.4GHz is ideal -- actually, between 1GHz and 3GHz. We tried 5.8GHz as well and the performance was seriously lacking.
Using 500mW to a 20dBi yagi vertically polarized on both ends yielded 20Mbps down and 900Kbps uplink over a 4 mile, snowy path at 2.4GHz. Surprisingly, horizontal polarization was not a good match, but we expected otherwise.