ZCZC SPCSWOMCD ALL ACUS11 KWNS 300203 SPC MCD 300203 ALZ000-MSZ000-LAZ000-300430- MESOSCALE DISCUSSION 1847 NWS STORM PREDICTION CENTER NORMAN OK 0803 PM CST TUE NOV 29 2016 AREAS AFFECTED...PORTIONS OF MS...LA...AND WESTERN AL CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY VALID 300203Z - 300430Z PROBABILITY OF WATCH ISSUANCE...95 PERCENT SUMMARY...A NEW TORNADO WATCH IS FORTHCOMING. THE RISK FOR SEVERE THUNDERSTORMS WILL CONTINUE INTO THE OVERNIGHT HOURS...INCLUDING NOCTURNAL TORNADO POTENTIAL. SIGNIFICANT TORNADOES WILL BE POSSIBLE. DISCUSSION...RICH LOW-LEVEL MOISTURE CONTINUES TO STREAM NORTHWARD OVER A BROAD PORTION OF THE LOWER MS VALLEY...EXTENDING TO A CONVECTIVELY REINFORCED BOUNDARY ANALYZED FROM MIDDLE TN SOUTHWESTWARD THROUGH NORTHERN/CENTRAL MS AND INTO SOUTHWEST LA AND SOUTHEAST TX. LOWER 70S SURFACE DEWPOINTS ALREADY EXTEND NORTHWARD INTO CENTRAL MS. RADAR LOOPS CONTINUE TO INDICATE AN UPTICK IN SMALL BANDED CONVECTIVE STRUCTURES ACROSS SOUTHERN LA...WITH TRAINING SUPERCELLS ONGOING FROM NORTHEAST LA INTO NORTHEAST/EAST-CENTRAL MS AND INTO WESTERN AL. LARGE-SCALE ASCENT SHOULD REMAIN MODEST THROUGH THE OVERNIGHT HOURS. HOWEVER...THE RENEWED INFLUX OF RICH GULF MOISTURE AMIDST A PERSISTENT WARM-ADVECTION PATTERN -- AIDED BY A STRENGTHENING LOW-LEVEL JET -- WILL LIKELY SUPPORT FURTHER NOCTURNAL INCREASES IN CONVECTIVE COVERAGE AND INTENSITY. AMPLE BOUNDARY-LAYER MOISTURE WILL LIKELY SUPPORT MLCAPE HOLDING AROUND 500-1500 J/KG THROUGH THE OVERNIGHT HOURS...WITH MINIMAL MLCINH. FURTHERMORE...WITH THE LCH 00Z RAOB SAMPLING A 7.4-C/KM LAPSE RATE IN THE H7-H5 LAYER...MODERATELY STEEP MID-LEVEL LAPSE RATES WILL SPREAD ACROSS THE REGION IN SUPPORT OF ENHANCED...STORM-SCALE...UPWARD ACCELERATIONS. A MIX OF CONVECTIVE MODES...INCLUDING SUSTAINED SUPERCELL STRUCTURES... WILL LIKELY LAST WELL INTO THE OVERNIGHT HOURS...AIDED BY 50-65 KT OF EFFECTIVE SHEAR. FURTHERMORE...WITH EFFECTIVE SRH AROUND 200-400 M2/S2 SUPPORTED BY AMPLE LOW-LEVEL DIRECTIONAL/SPEED SHEAR... THERE WILL EXIST A TORNADO RISK THROUGH THE OVERNIGHT HOURS. A SIGNIFICANT-TORNADO RISK WILL EXIST...ESPECIALLY WITH THE MORE SUSTAINED SUPERCELLS. A NEW TORNADO WATCH WILL BE ISSUED FOR A BROAD PORTION OF THE LOWER MS VALLEY AND VICINITY TO ADDRESS THE TORNADO RISK LASTING THROUGH THE OVERNIGHT HOURS. ..COHEN/HART.. 11/30/2016 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...BMX...MOB...MEG...JAN...LIX...LCH...SHV... LAT...LON 30259324 31199298 32379184 33938942 34188798 33668713 32638758 31008928 29999099 29939248 30259324 NNNN