USA Weather — Severe Weather Division
This outlook is expired and is no longer valid.
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS THE ARKLATEX INTO THE LOWER MISSISSIPPI VALLEY...
...SUMMARY...
SEVERE THUNDERSTORMS ARE EXPECTED FROM THE SOUTHERN PLAINS INTO THE OHIO VALLEY ON TUESDAY, PARTICULARLY FROM THE ARKLATEX INTO THE LOWER MISSISSIPPI VALLEY AND MID-SOUTH. FAIRLY NUMEROUS DAMAGING WIND GUSTS AND VERY LARGE HAIL ARE THE PRIMARY THREATS, THOUGH A COUPLE OF TORNADOES WILL BE POSSIBLE.
...SYNOPSIS...
AN INCREASINGLY ZONAL PATTERN WILL BEGIN TO DEVELOP ACROSS THE SOUTHERN AND EASTERN CONUS TUESDAY AS A MID-LEVEL RIDGE CENTERED OVER THE GULF BEGINS TO ERODE/FLATTEN OUT WHILE A LARGE UPPER TROUGH SLOWLY DIGS INTO THE NORTH CENTRAL US. WITHIN THE 60-80KT 500MB FLOW, A RATHER PRONOUNCED SHORTWAVE TROUGH QUICKLY SLIDES EASTWARD FROM THE SOUTHERN HIGH PLAINS AT THE START OF THE PERIOD INTO THE OZARKS BY TUESDAY EVENING. AT THE SURFACE, A STALLING COLD FRONT ACROSS THE SOUTHERN PLAINS INTO THE OHIO VALLEY WILL SLOWLY LIFT NORTHWARD BY TUESDAY AFTERNOON, POTENTIALLY WITH A WEAK SURFACE LOW DEVELOPING AND MOVING EAST ALONG THE FRONT AS A RESULT OF THE SHORTWAVE PASSING OVERHEAD.
...SOUTHERN PLAINS, ARKLATEX, AND LOWER MISSISSIPPI VALLEY...
ISOLATED MORNING CONVECTION COULD STILL BE ONGOING AT 12Z ACROSS PORTIONS OF THE REGION, ESPECIALLY OVER NORTHERN TEXAS, WHERE A COUPLE LEFT-OVER SUPERCELLS PRODUCING LARGE HAIL WILL BE POSSIBLE. THESE STORMS WILL GRADUALLY WEAKEN AND DISSIPATE DURING THE MORNING HOURS. SIGNIFICANT MOISTURE POOLING ALONG THE SURFACE FRONT WILL SUPPORT LOW TO MID 70S DEWPOINTS ACROSS CENTRAL/NORTHERN TEXAS INTO THE ARKLATEX AND LOWER MISSISSIPPI VALLEY, ESPECIALLY THE MS DELTA REGION. MODERATE TO STRONG DIURNAL HEATING UNDERNEATH AN IMPRESSIVE EML CONTRIBUTING TO 8.5-9.0 C/KM LAPSE RATES WILL SUPPORT STRONG TO EXTREME INSTABILITY BY THE EARLY AFTERNOON HOURS. MLCAPE EXCEEDING 4000-5000 J/KG WILL BE COMMON ACROSS THE ARKLATEX, WITH SOME LOCATIONS POTENTIALLY REACHING 6000 J/KG AT PEAK HEATING, MOST LIKELY NEAR THE DRYLINE OVER CENTRAL TEXAS AND ALONG THE STATIONARY FRONT FURTHER EAST.
NUMEROUS TO WIDESPREAD THUNDERSTORMS WILL INITIATE BY EARLY AFTERNOON AS THE SHORTWAVE MOVES OVERHEAD, WITH INITIATION EXPECTED ALONG THE DRYLINE, THE STATIONARY FRONT, AND ALONG MOISTURE CONVERGENCE ZONES OR LEFT-OVER OUTFLOW BOUNDARIES FROM LATE IN THE D1 PERIOD. THE STRONG ZONAL UPPER LEVEL FLOW ALONG WITH MODERATE SOUTHWESTERLY LOW-LEVEL JET WINDS WILL SUPPORT IMPRESSIVELY ELONGATED HODOGRAPHS AND DEEP-LAYER SHEAR IN EXCESS OF 50KT. INITIAL ACTIVITY IN THE FORM OF SUPERCELLS AND LINEAR CLUSTERS WILL PRODUCE A THREAT FOR VERY LARGE HAIL AND DAMAGING WIND GUSTS AS THEY BEGIN TO SPREAD EAST. RATHER QUICK UPSCALE GROWTH BY MID-AFTERNOON WILL SUPPORT THE DEVELOPMENT OF ONE OR MORE ORGANIZED LINEAR COMPLEXES WITH DAMAGING WINDS QUITE LIKELY, INCLUDING POTENTIAL FOR EMBEDDED GUSTS OVER 75 MPH. WHILE LOW-LEVEL SHEAR WILL REMAIN FAIRLY MODEST, THERE WILL STILL BE 200-250 M2/S2 EFFECTIVE SRH, PARTICULARLY NEAR SURFACE BOUNDARIES, WHICH SHOULD SUPPORT A THREAT FOR A FEW TORNADOES WITHIN ANY MORE INTENSE SUPERCELL WITHIN THIS AREA OR A COUPLE EMBEDDED QLCS TORNADOES. CAMS DIVERGE IN THE EVOLUTION OF STORMS BY THIS POINT, WITH SOME GUIDANCE, NOTABLY HRRR AND WRF SUGGEST A STRONG MCS DEVELOPS OVER NORTHEAST TEXAS AND PROPAGATES EASTWARD ALONG THE STATIONARY FRONT PRODUCING WIDESPREAD DAMAGING WINDS, WHILE OTHERS SUCH AS MPAS, NAM, AND RRFS SUGGESTING WIDESPREAD CONVECTION ALSO DEVELOPING LATERALLY ALONG THE STATIONARY FRONT WITH SEVERAL BOWING SEGMENTS AND EMBEDDED HAIL CORES PRODUCING FAIRLY NUMEROUS TO WIDESPREAD SEVERE WIND/HAIL, THOUGH WITHOUT A CONCENTRATED CORRIDOR FOR ENHANCED SIGNIFICANT WIND POTENTIAL AS WOULD A MORE ORGANIZED MCS PRODUCE. REGARDLESS, ENOUGH CONFIDENCE EXISTS TO INCLUDE AN ENHANCED RISK FOR SEVERE WIND AND HAIL DUE TO THE WIDESPREAD NATURE OF STORMS IN ANY SCENARIO.