…MIDWEST/MIDDLE MS RIVER VALLEY TO SOUTH-CENTRAL PLAINS…
AN UPPER TROUGH…CURRENTLY OVER THE PACIFIC NORTHWEST…WILL AMPLIFY/ADVANCE SOUTHEASTWARD IN A POSITIVE-TILT FASHION FROM THE NORTHERN/CENTRAL ROCKIES EARLY SUNDAY TO THE UPPER MIDWEST AND CENTRAL/SOUTHERN HIGH PLAINS BY LATE SUNDAY NIGHT. BENEATH A STRONG ELEVATED MIXED LAYER/CAP…LOW LEVEL MOISTURE WILL AGGRESSIVELY RETURN NORTHEASTWARD DURING THE DAY WITH AID OF A 50-70 KT SOUTHWESTERLY LOW LEVEL JET. GENERALLY LOWER 60S F SURFACE DEWPOINTS WILL BECOME ESTABLISHED BY MID/LATE AFTERNOON WITHIN THE PRE-COLD FRONTAL WARM SECTOR ACROSS THE MIDWEST/LOWER MO VALLEY.

THE AFOREMENTIONED CAP SHOULD PRECLUDE SURFACE BASED TSTM DEVELOPMENT THROUGH MUCH OF THE AFTERNOON. THAT SAID…INITIAL DEEP CONVECTIVE DEVELOPMENT SEEMS PROBABLE BY LATE AFTERNOON/EARLY EVENING IN VICINITY OF THE COLD FRONT ACROSS SOUTHEAST IA/NORTHWEST IL AND NORTHERN MO…SOUTHWESTWARD TO NEAR A TRIPLE POINT/DRYLINE INTERSECTION ACROSS EAST-CENTRAL/SOUTH-CENTRAL KS.

WITH MODERATE INSTABILITY/VERY STEEP LAPSE RATES ACROSS THE WARM SECTOR…STRONG DEEP LAYER SHEAR AMID 50-60 KT SOUTHWESTERLY MID LEVEL FLOW WILL SUPPORT AN INITIAL MODE OF SUPERCELLS CAPABLE OF LARGE HAIL AND SOME TORNADOES…WITH THE RELATIVELY GREATEST PROBABILITY OF TORNADOES APPEARING TO BE ACROSS PORTIONS OF FAR EASTERN IA AND NORTHERN IL/NORTHEAST MO. A DAMAGING WIND THREAT WILL UNFOLD AS WELL DURING THE EARLY/MID EVENING HOURS AS STORMS CONGEAL/BOWS EVOLVE AMIDST NOCTURNALLY REINVIGORATED FLOW WITHIN THE LOWEST FEW KM /70+ KT AT 850 MB/. WHILE A VERY STRONG WIND FIELD WILL REMAIN FAVORABLE FOR SUSTAINED SUPERCELLS OR MORE LIKELY FAST MOVING QUASI-LINEAR CONVECTION/BOWS SUNDAY NIGHT…MODEST BOUNDARY LAYER MOISTURE/ASSOCIATED DECOUPLING IMPLIES AN INCREASINGLY MORE ISOLATED/MARGINAL SEVERE THREAT BY LATE EVENING/OVERNIGHT ACROSS THE MIDWEST.