Mesoscale Discussion 1831 NWS Storm Prediction Center Norman OK 0906 AM CDT Mon Oct 11 2021 Areas affected...eastern MO...western and central IL Concerning...Severe potential...Watch possible Valid 111406Z - 111630Z Probability of Watch Issuance...60 percent SUMMARY...Trends will be monitored this morning for surface-based thunderstorm development. The initial area of concern will be over central MO and areas northeastward towards the MS River. A tornado watch will likely be needed by midday for portions of eastern MO into western IL. It is uncertain whether surface-based storms and a subsequent tornado risk will develop as far north as extreme eastern IA. DISCUSSION...Visible-satellite imagery shows a compact/intense mid-level shortwave trough over the lower MO Valley. Weak convection has been maintained this morning within the warm conveyer belt from southeast MO through the Saint Louis area and into western IL. A surface trough/windshift is analyzed this morning arcing from near the low through central and south-central MO. A small area of cloud breaks is noted in visible-satellite imagery over central MO where forcing is maximized and over the location of greatest concern this morning. Model forecast soundings show gradual destabilization this morning into the midday hours as temperatures slowly rise into the lower 70s with a moist boundary layer. Very strong low-level flow noted at the Saint Louis 88D VAD is resulting in a large low-level hodograph (400+ m2/s2 0-1 km SRH). Once sufficiently strong updrafts can develop/persist, a severe risk will likely ensue with an isolated risk for tornadoes and damaging winds being the primary concerns.