At 04Z, the surface low was centered very close to Kansas City, MO. The warm front has again begun advancing northward and extends east from the center of the low to Quincy, IL-Normal/Bloomington, IL-near Watseka, IL. The dryline extends SW from the low to near Bartlesville, OK-Seminole, OK-Ardmore, OK. Dew points S of the warm front and E of the dryline continue in the low/mid 60s with MUCAPE AOA 1500 J/Kg.
The 'ever-lasting' supercell continues into east-central IL and latest OA indicates that instability decreases towards the IL/IN border, so we may finally see a decay of this extremely long-track supercell storm.
Other supercells have formed in SW MO from the previously broken line of storms that formed several hours ago in SW KS and NE OK. A 60 Kt LLJ is contributing to 0-3 Km SRH in excess of 500 m^2/s^2 over much of MO and N AR, so I would expect these supercells to persist.
A squall line is developing along the dryline as it begins advancing east. I would expect this squall line to fill in and intensify as the surface cold front catches up to the dryline overnight. Large hail and damaging winds will be the primary threats with the squall line as it will probably last through Monday morning.