ZCZC SPCSWOMCD ALL ACUS11 KWNS 122254 SPC MCD 122254 KSZ000-OKZ000-TXZ000-130100- MESOSCALE DISCUSSION 1683 NWS STORM PREDICTION CENTER NORMAN OK 0554 PM CDT MON SEP 12 2016 AREAS AFFECTED...PORTIONS OF THE TX/OK PANHANDLES...NWRN OK...AND WRN/CNTRL KS CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY VALID 122254Z - 130100Z PROBABILITY OF WATCH ISSUANCE...20 PERCENT SUMMARY...AN ISOLATED LARGE HAIL AND DAMAGING WIND RISK IS FORECAST TO DEVELOP THROUGH 01Z. WW ISSUANCE IS UNLIKELY. DISCUSSION...ATTEMPTS AT CONVECTIVE INITIATION ALONG A SLOWLY SWD MOVING COLD FRONT ACROSS KS HAVE FAILED SO FAR THIS AFTERNOON...MAINLY DUE TO STOUT MID-LEVEL CAPPING INDICATED ON AREA 12Z SOUNDINGS. WITH TIME...LIFT ASSOCIATED WITH A STRENGTHENING LOW-LEVEL JET ACROSS THE MCD AREA COMBINED WITH AT LEAST THE GLANCING INFLUENCE OF LARGE-SCALE ASCENT ATTENDANT TO A SUBTLE MID-LEVEL IMPULSE OVER THE CNTRL ROCKIES SHOULD ACT TO INITIATE THUNDERSTORMS ALONG THE FRONT BY 01Z. MOST NEAR-TERM CONVECTION ALLOWING MODEL GUIDANCE...INCLUDING RECENT RUNS OF THE HRRR...ARE IN GENERAL AGREEMENT WITH THIS SCENARIO. THE AIRMASS ALONG/S OF THE FRONT IS WEAKLY TO MODERATELY UNSTABLE...AS SFC TEMPERATURES HAVE WARMED GENERALLY INTO THE MID 80S TO LOWER 90S...AND DEWPOINTS RANGE FROM THE MID 50S TO LOWER 60S. RAP FORECAST SOUNDINGS SHOW STEEP MID-LEVEL LAPSE RATES HAVE OVERSPREAD THE MCD AREA FROM THE W...AND ESTIMATES OF 1000-2000 J/KG MLCAPE FROM 22Z RAP MESOANALYSIS SEEM REASONABLE. A VEERING LOW-LEVEL WIND PROFILE AND AROUND 30 KT OF MID-LEVEL FLOW SHOULD ALLOW FOR SOME STORM ORGANIZATION. DUE TO THE LINEAR NATURE OF THE SFC FORCING MECHANISM /COLD FRONT/ INITIALLY ISOLATED CONVECTION SHOULD QUICKLY GROW UPSCALE INTO CLUSTERS. ISOLATED INSTANCES OF LARGE HAIL MAY BE THE PRIMARY INITIAL THREAT...TRANSITIONING TO MAINLY A STRONG/DAMAGING WIND RISK WITH TIME. SOME RECENT GUIDANCE SUGGESTS ISOLATED THUNDERSTORMS OVER SERN CO MAY INTENSIFY AND EVENTUALLY GROW UPSCALE INTO A SMALL CLUSTER OVER THE TX/OK PANHANDLES AND FAR SWRN KS AS THEY MOVE EWD OVER THE NEXT SEVERAL HOURS AND ENCOUNTER A MORE UNSTABLE AIRMASS S OF THE FRONT. REGARDLESS...OVERALL SEVERE RISK SHOULD REMAIN FAIRLY ISOLATED WITH THE LACK OF EVEN STRONGER MID-LEVEL FLOW AND THE TENDENCY FOR CONVECTION TO BECOME ELEVATED AS THE COLD FRONT UNDERCUTS IT. ..GLEASON/GUYER.. 09/12/2016 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...ICT...OUN...GID...DDC...AMA... LAT...LON 37689991 38979918 39259884 39399832 39209798 37659798 36479934 36110075 36150187 36780193 37170139 37320043 37689991 NNNN