Flood of May 1st and Late Season Cold

On May 1st, this enormous trough produced a tornado outbreak and historic flooding in western and central Tennessee.Dewpoints in the lower Mississippi valley were in the mid to upper 70s.
CAPE was over 5,000 J/kg:
About a dozen supercell thunderstorms quickly developed over Arkansas.
I don't ever remember seeing more tornado warnings in such a small area.
This was the beginning of the historic flooding in Tennessee, were they were already on the nose of a broad low level jet:The 13.57 inches of rain that Nashville received on May 1st & 2nd not only set new records for 6 hour, 12 hour, 24 hour, calendar day, and two day rainfall, but also broke the old record of 11.04 inches for the entire month of May! The highest rainfall total reported was near Camden, TN with 19.41 inches.

A late season cold spell prompted frost and freeze advisories across the Midwest and Northeast from May 8th-11th. On May 8th there were wind advisories for the Northeast, gale warnings for the East Coast and all of the Great Lakes, and winter weather advisories for the upper Great Lakes.
On May 24th, Salt Lake City had their latest measurable (0.2") snowfall on record, beating the old record by 6 days, and a record low of 33F.

In addition, up to 20 inches of snow fell in Vermont in late April and snow continued into mid-May in Colorado, where the snow was reported to be pink and red on April 29th because of a dust storm in northeast Arizona the previous day.