Winter-like arctic air in place across the entire Eastern half of the U.S. will linger longest over the Southeast into early Tuesday at near 20° below average intensity where NWS overnight Freeze Warnings remain in place. Meanwhile the central U.S. is already warming above average and this warmer airmass will reach  the Eastern U.S. midweek in milder southerly flow ahead of the next series of closely spaced Pacific storms lined up to move onto the West Coast at 36-48 hour intervals. The lead Western storm forecast to eject east of the Rockies midweek and the East Saturday will not tap into cold air nearly as intense as 20°-30° below average temperatures observed last week. However, very cold air by spring standards remains available over snow covered Canada to be tapped by the parade of coast to coast tracking storms to frequently cool temperatures across most of the Eastern half of the U.S. to at least moderately (7°-10°) below average levels starting during the latter half of this week. Several additional rounds of late season snow are also forecast across most of the northeastern quadrant of the U.S. including a potential significant winter storm in the interior Northeast at the end of the 6-10 day period (Mar 28-29). More importantly all extended models prolong this active cold-biased U.S. storm pattern devoid of sustained above average warmth (or Southeastern ridging), adding confidence to continued delay of full establishment of spring-like temperatures across most of the Eastern U.S. into mid April.