TSTM INITIATION IS LIKELY BETWEEN 22-23Z AND SUPERCELLS WITH VERY LARGE HAIL…DAMAGING WIND GUSTS AND PERHAPS A TORNADO WILL BE POSSIBLE. WW IS LIKELY…ROUGHLY 70 PERCENT CHANCE.

CUMULUS FIELD WAS DEEPENING LATE THIS AFTERNOON ACROSS SCNTRL/SERN IA AND EXTREME NCNTRL MO WITHIN A WEAKENING CAP ALONG NOSE OF STEEP LOW-LEVEL LAPSE RATES. APPROACH OF LARGE-SCALE HEIGHT FALLS…NOW OVER ERN NEB…WILL LIKELY BOOST OVERALL ASCENT AND AID IN TSTM INITIATION ACROSS SCNTRL/SERN IA BY 23Z…SIMILAR TO LATEST RAPID REFRESH AND RUC SOLUTIONS. ONCE STORMS BECOME ESTABLISHED…MLCAPES TO 2000 J/KG AND VERTICAL SHEAR OF 40-45 KTS WILL BE FAVORABLE FOR ROBUST ROTATING UPDRAFTS. VERY STEEP MID-LEVEL LAPSE RATES WILL YIELD VERY LARGE HAIL…ALTHOUGH A TORNADO/DAMAGING WINDS WILL ALSO BE POSSIBLE.

ACTIVITY MAY BACKBUILD SWWD ALONG THE APPROACH COLD FRONT LATER THIS EVENING INTO NCNTRL MO…THOUGH COMPARATIVELY STRONGER CAP RENDERS MORE UNCERTAINTY ACROSS THIS AREA.