ZCZC SPCSWOMCD ALL ACUS11 KWNS 170050 SPC MCD 170050 NEZ000-170215- MESOSCALE DISCUSSION 1954 NWS STORM PREDICTION CENTER NORMAN OK 0650 PM CST MON NOV 16 2015 AREAS AFFECTED...PORTIONS OF CENTRAL NEBRASKA CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY VALID 170050Z - 170215Z PROBABILITY OF WATCH ISSUANCE...20 PERCENT SUMMARY...LOCALIZED SEVERE WEATHER THREAT WILL EXIST FOR A FEW HOURS NORTH OF THE CURRENT SEVERE WEATHER WATCHES WITHIN A DEVELOPING CONVECTIVE LINE SEGMENT IN THE VICINITY OF A DEVELOPING MESOSCALE VORTEX. ALL SEVERE HAZARDS REMAIN POSSIBLE BEFORE STORMS OUTRUN THE NARROW ZONE OF INSTABILITY AND MAY REQUIRE A LOCAL EXTENSION OF WW #0538. DISCUSSION...A MESOSCALE VORTEX HAS DEVELOPED IN AN EXPANDING QUASI-LINEAR CONVECTIVE SYSTEM EXTENDING NORTHWARD INTO CUSTER COUNTY PER KLNX VELOCITY AHEAD OF A NARROW ZONE OF POSITIVE BUOYANCY THAT HAS SPREAD NORTHWARD TO ABOUT 42 DEG N LATITUDE AND EASTWARD INTO THE GRAND ISLAND AREA. ALTHOUGH SURFACE TEMPERATURES ARE COOLING DIURNALLY AND UNDER LIGHT PRECIPITATION AHEAD OF THE APPROACHING STORMS...THE SURFACE STABLE LAYER LIKELY REMAINS SHALLOW...AND ANY LOCALIZED CIRCULATIONS THAT DEVELOP ALONG THE LEADING EDGE OF THE SYSTEM MAY NOT BE DECOUPLED FROM THE GROUND IN THE NEXT FEW HOURS. THE 0-1 KM SHEAR IN EXCESS OF 30 KT ORIENTED NORMAL TO THE SURGING LINE SUGGESTS A POTENTIAL FOR QLCS TORNADOES WITH THIS ACTIVITY. FURTHERMORE...ALTHOUGH THE STRONG 850-700 MB FLOW IN EXCESS OF 50 KT REMAINS SOUTH OF THE MCD AREA...THEREBY LIMITING THE CONTRIBUTION OF MOMENTUM TRANSFER TO SEVERE WIND PRODUCTION...A NARROW MESO-BETA SCALE AREA OF REAR-INFLOW HAS DEVELOPED IN ASSOCIATION WITH THE MESOVORTEX THAT COULD ENHANCE THE SEVERE WIND POTENTIAL WITH THIS LINE. HOWEVER...THE SPATIAL COVERAGE AND DURATION OF THIS PARTICULAR THREAT IS EXPECTED TO REMAIN SMALL ENOUGH TO PREVENT THE NEED FOR A WATCH AT THIS TIME BUT MAY REQUIRE A LOCAL EXTENSION OF WW #0538 INTO CUSTER COUNTY. ..CONIGLIO/CORFIDI.. 11/17/2015 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...OAX...GID...LBF... LAT...LON 41300005 41599987 41759950 41929902 41909859 41829829 41699807 41429794 41369805 41209834 41139901 41069951 41079996 41080017 41300005 NNNN