The coldest air of the season flooding the West this past weekend spread into the central U.S. early this week, but temperatures west of the Rockies will be slow to moderate as additional snow-producing storms track through mainly northern portions of the region this week. While another multiday warming trend underway across the Midwest and East is forecast to peak temperatures 10°-15° above average during the 1^st half of this week, a pair of progressively colder and wetter late week storms are certain to end above average warmth for the longest consecutive day stretch of fall.  During this prolonged cool period latest models extend through the entire final week of November the 1^st snow of the season is also forecast in portions of the Ohio Valley, Appalachians, and interior Northeast. Both cold air intensity and Eastern snow appear underdone in recent modeling as forecasts struggle with strong dynamics associated with an unseasonably cold closed low set to deepen between the northern Plains and Ohio Valley mid-late workweek before slowly lifting through the Northeast next weekend (Nov 23-24).  Winter-like overnight low temperatures in the 30s extending deep into northern Texas and the Southeast by the end of this workweek will be especially noticeable after the unseasonably warm November still underway across the southeast quadrant of the U.S. and even daytime highs are considered likely to bottom out near 10° below average across most of the Midwest and East. Milder temperatures remain on track to return to the Eastern U.S. in early December while colder air lingering between western Canada and the Pacific Northwest air drains back into portions of the Southwest. However longer range 30-day MWA ensemble forecasts spread this next notably colder Western airmass back into the Eastern U.S. during the 2^nd week of December generating another extended period of seasonal to moderately below average temperatures on the order of one full week or more, setting the stage for a colder start to winter than typical during La Niña.