829
ACUS3 KMKC 241508
SWOMCD
MKC MCD 241507
ILZ000-MOZ000-241800-

SPC MESOSCALE DISCUSSION 2197 FOR PARTS OF ERN MO ACROSS
CENTRAL/SRN IL
CONCERNING...SEVERE THUNDERSTORM POTENTIAL...

MONITORING FOR WW IN THE NEXT HOUR OR SO.

CONVECTION CONTINUES TO INCREASE AND REMAIN RATHER DISCRETE ATTM
AHEAD OF PRIMARY COLD FRONT EXTENDING FROM SWRN MO INTO NRN IL.
VISIBLE IMAGERY INDICATES A WELL DEFINED PRE-FRONTAL CONVERGENCE
LINE NOW MOVING ACROSS THE STL AREA SWWD INTO N-CENTRAL AR...WHILE
WARM FRONT/OUTFLOW BOUNDARY ARCS FROM SRN IND NWWD AND INTERSECTS
CONVERGENCE LINE OVER FAR W-CENTRAL IL.

FORECAST SOUNDINGS INDICATE VERY STEEP LAPSE RATES WHICH ARE
PROVIDING FAIRLY STRONG CAP ACROSS THE WARM SECTOR ATTM.  IN
ADDITION...LOW CLOUDS MAY CONTINUE TO SUPPRESS HEATING FOR A FEW
MORE HOURS AND MAY ACT TO LIMIT SURFACE-BASED DEVELOPMENT INTO THE
LATE MORNING.  HOWEVER...ETAKF AND LATEST RUC GUIDANCE CONTINUE TO
INDICATE STRONG VERTICAL MOTION AND INCREASING CONVECTION INVOF THE
MID MS RIVER VALLEY THROUGH 18Z.

PRIMARY CONCERN ATTM REGARDS AFFECT PRE-FRONTAL CONVERGENCE LINE
WILL HAVE ON SURFACE-BASED DEVELOPMENT.  INITIAL ACTIVITY MAY
REMAIN SLIGHTLY ELEVATED ABOVE CAPPED BOUNDARY LAYER...THOUGH
SUPERCELL POTENTIAL WOULD INCREASE THE THREAT OF LARGE HAIL.  LONG-
LIVED SUPERCELLS MAY INITIATE DURING THE LATE MORNING...ESPECIALLY
INVOF TRIPLE POINT NOW OVER W-CENTRAL IL...AS CAP WEAKENS AND LOW
LEVEL CONVERGENCE INCREASES.

..EVANS.. 10/24/01