A major winter storm will enter Arizona early Thanksgiving Day morning. A prolonged period of heavy snowfall is expected Thursday into Friday, which will bring heafty snow accumulations to much of the region. Snow levels Thanksgiving day will initially hover near 6000' in elevation and gradually lower to 5500' by evening. Snow levels crash to near 3500' Thursday night into the day Friday. Preliminary indications are for 12 - 27" of snow above 6000', 4 - 12" between 4500' - 6000', and a few inches down to valley floors. The National Weather Service has issued Winter Storm Watches for elevations above 4500' through the period. Travel will be difficult if not impossible from Thursday late morning through Friday evening. The storm is expected to clear Saturday morning.