ZCZC SPCSWOMCD ALL ACUS11 KWNS 241850 SPC MCD 241850 KSZ000-OKZ000-242115- MESOSCALE DISCUSSION 0437 NWS STORM PREDICTION CENTER NORMAN OK 0150 PM CDT SUN APR 24 2016 AREAS AFFECTED...CNTRL KS INTO NWRN OK CONCERNING...SEVERE POTENTIAL...WATCH LIKELY VALID 241850Z - 242115Z PROBABILITY OF WATCH ISSUANCE...80 PERCENT SUMMARY...WIDELY SCATTERED CONVECTIVE INITIATION IS LIKELY DURING THE 20-22Z PERIOD OVER KS AND ISOLATED CONVECTIVE INITIATION IS PROBABLE DURING THE 22-01Z PERIOD FROM THE KS-OK BORDER REGION SWD INTO OK. LARGE TO VERY LARGE HAIL WILL BE POSSIBLE WITH STRONGER UPDRAFTS THAT DEVELOP INTO SUPERCELLS. A MODEST WEAK-TORNADO RISK WILL BE CONFINED TO THE EARLY EVENING /23-02Z/ WHEN LOW-LEVEL SHEAR STRENGTHENS AND TEMP/DEWPOINT SPREADS LOWER. DISCUSSION...18Z SURFACE ANALYSIS PLACES A SHARPENING DRYLINE/CONFLUENT LOW-LEVEL FLOW FROM 25 MI W RSL SWD ALONG THE TX-OK BORDER. DEWPOINTS HAVE RISEN INTO THE 59-62 DEG F RANGE DURING THE PAST FEW HOURS IN W-CNTRL OK PER OK MESONET OBSERVATIONS. STRONG HEATING COUPLED WITH GRADUAL MOISTENING ARE CONTRIBUTING TO MODERATE BUOYANCY. WATER VAPOR IMAGERY SHOWS A WELL-DEFINED MID-LEVEL VORTICITY MAXIMUM ROTATING THROUGH THE BASE OF LARGER-SCALE TROUGH ACROSS W-CNTRL KS EARLY THIS AFTERNOON. THIS FEATURE WILL MOVE INTO CNTRL AND ERN PORTIONS OF KS/S-CNTRL NEB BY LATE AFTERNOON. THE TRAILING PORTION OF THIS FEATURE AND IMPLIED WEAK ASCENT WILL SPREAD ACROSS NWRN OK DURING THE LATE AFTERNOON/EARLY EVENING. SURFACE OBSERVATIONS DURING THE PAST FEW HOURS IMPLY THE SPC RAP-BASED OBJECTIVE ANALYSES ARE SUFFERING FROM THE RAP OVER-MIXING DRY BIAS YIELDING AN UNDER-REPRESENTATION OF LOW-LEVEL MOISTURE. WRF-BASED GUIDANCE /PARTICULARLY THE NAM/ APPEARS TO EXHIBIT A MORE REASONABLE SOLUTION REGARDING MOISTURE/MIXING AND SUBSEQUENT CAP EROSION AND CONVECTIVE INITIATION PROCESSES. CONVECTIVE INITIATION WILL LIKELY OCCUR FIRST ACROSS CNTRL KS ALONG THE DRYLINE AND GRADUALLY INCLUDE AREAS FARTHER S ALONG THE KS/OK BORDER BY LATE THIS AFTERNOON AND INTO NWRN OK DURING THE EARLY EVENING HOURS. DEEP SHEAR VECTORS ORIENTED ORTHOGONAL TO THE SURFACE BOUNDARIES COUPLED WITH EFFECTIVE SHEAR MAGNITUDES OF 40-50 KT WILL FAVOR DISCRETE SUPERCELL MODE WITH THE STRONGER/SUSTAINED UPDRAFTS. LOW-LEVEL SHEAR /I.E. SRH/ RISES INTO THE 100-250 M2/S2 RANGE DURING THE 23-02Z PERIOD AND WILL GENERALLY COINCIDE WITH SOME WEAK TORNADO POTENTIAL WITH ANY STRONGER/SUSTAINED SUPERCELL. STRENGTHENING CONVECTIVE INHIBITION AFTER 01-02Z WILL TEND TO RESTRICT STORM INTENSITY/COVERAGE THIS EVENING AS MOST OF THE ACTIVITY DIMINISHES. ..SMITH/CORFIDI.. 04/24/2016 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...TOP...ICT...OUN...GID...DDC... LAT...LON 36219954 39369873 39799813 39829708 39409668 35889771 35739814 35739923 36219954 NNNN