Good Chance of Snow in Tucson Sunday Morning

The last few times before this, over the last few years, when the prospect of accumulating snow in Tucson has been played up, I have been skeptical. The most likely scenario always was for drier air to arrive with the coldest air. This time is different. Before the arctic air turns east and moves rapidly toward Tucson overnight Saturday, it will have had a long time to pick up moisture from the Pacific while hugging the California coast from San Francisco (overnight Friday) to Los Angeles (Saturday evening). The system will be moving east through Tucson rapidly on Sunday, and drier air should sweep in well before noon (per the consistent run-to-run GFS 700 mb RH progs for 18Z). And the heaviest precipitation should be all rain both in the foothills and in the valley until almost sunrise on Sunday. But there could well be a few hours of light, wet snow either side of sunrise when about a half-inch, maybe an inch average accumulates.