Categorical Day1 2000Z Outlook
RiskArea (sq. mi.)Area Pop.Some Larger Population
Centers in Risk Area
HIGH17,5161,102,272Little Rock, AR...Camden, AR...Danville,
AR...MODERATE42,8442,353,693Springfield, MO...Ft. Smith, AR...Texarkana, TX...Mountain Home, AR...Brinkley, AR..
.SLIGHT357,60925,411,567Memphis, TN...Kansas City, MO...Omaha, NE...St. Louis, MO...Lincoln, NE...
Forecast Discussion
SPC AC 272000 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0300 PM CDT SUN APR 27 2014 VALID 272000Z - 281200Z ...THERE IS A HIGH RISK OF SVR TSTMS ACROSS MUCH OF CNTRL AR... ...THERE IS A MDT RISK OF SVR TSTMS ACROSS MUCH OF AR...NERN TX...FAR ERN OK AND SRN MO... ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS MUCH OF THE MID AND LOWER MO VALLEY SWD INTO THE MIDDLE AND LOWER MS VALLEY AND ARKLATEX... ...SUMMARY... SEVERE THUNDERSTORMS WILL AFFECT ARKANSAS AND ADJACENT AREAS OF SOUTHERN MISSOURI...EASTERN OKLAHOMA...AND EXTREME NORTHEAST TEXAS THIS AFTERNOON INTO TONIGHT. THE GREATEST TORNADO RISK WILL BE CENTERED ON ARKANSAS...WHERE A FEW STRONG AND LONG-TRACK TORNADOES WILL BE POSSIBLE THROUGH TONIGHT. OTHERWISE...A BAND OF SEVERE THUNDERSTORMS WILL MOVE ACROSS MISSOURI AND IOWA THIS AFTERNOON WITH DAMAGING WINDS...LARGE HAIL...AND A FEW TORNADOES. MORE ISOLATED SEVERE STORMS WILL BE POSSIBLE THIS AFTERNOON ACROSS CENTRAL NEBRASKA. ...ADDED HIGH RISK TO AR IN ANTICIPATION OF SUPERCELLS FORMING UPSTREAM OVER NERN TX AND ERN OK...WHICH WILL MATURE AS THEY MOVE INTO AR WHERE BETTER LOW LEVEL SHEAR EXISTS... MUCH OF AR...FAR NERN TX AND SRN MO STILL APPEARS TO BE THE GREATEST THREAT AREA FOR TORNADOES. INSTABILITY AND SHEAR PROFILES WILL CONTINUE TO BECOME MORE FAVORABLE THROUGHOUT THE AFTERNOON. VISIBLE SATELLITE SHOWS SIGNS OF CU BECOMING GRADUALLY DEEPER WITHIN THE LOW-LEVEL MOISTURE AXIS ACROSS NERN TX...SWRN AR AND NRN LA. SUPERCELLS WILL EVENTUALLY ERUPT ACROSS THESE AREAS...WITH STRONG TORNADOES POSSIBLE AS WELL AS VERY LARGE HAIL. ...NEB... STORMS CONTINUE TO BECOME MORE WIDESPREAD AHEAD OF THE SURFACE LOW WHERE HEATING HAS DESTABILIZED THE REGION. STEEP LAPSE RATES AND A VORTICITY-RICH ENVIRONMENT WILL CONTINUE TO FAVOR LOW-TOPPED SUPERCELLS CAPABLE OF HAIL AND A FEW TORNADOES. ...IA...MO...NERN KS... WHILE SOME MOISTURE REMAINS BEHIND THE INITIAL LINE OF STORMS...IT IS UNCLEAR WHETHER ENOUGH DESTABILIZATION WILL OCCUR FOR MORE SEVERE STORMS. WILL MAINTAIN A CONDITIONAL SLIGHT RISK IN THE WAKE OF THE EARLIER STORMS GIVEN HEATING AND DRYLINE POSITION...BUT THE OVERALL SEVERE RISK APPEARS LOW. ..JEWELL.. 04/27/2014 .PREV DISCUSSION... /ISSUED 1129 AM CDT SUN APR 27 2014/ ...SIGNIFICANT SEVERE WEATHER EPISODE STILL EXPECTED THIS AFTERNOON/TONIGHT CENTERED ON AR...WHERE A FEW STRONG/LONG-TRACK TORNADOES WILL BE POSSIBLE... ...SYNOPSIS... A STRONG MIDLEVEL SHORTWAVE TROUGH IS EVOLVING INTO A CLOSED LOW AS THE SYNOPTIC SYSTEM OCCLUDES OVER THE CENTRAL HIGH PLAINS. THE ASSOCIATED SURFACE CYCLONE APPEARS TO HAVE REACHED PEAK INTENSITY...AND IT WILL VERY SLOWLY WEAKEN WHILE MOVING EWD NEAR THE KS/NE BORDER THROUGH EARLY TONIGHT. A TRAILING COLD FRONT/DRYLINE WILL MOVE SLOWLY EWD ACROSS ERN KS/OK AND N TX. THE PRIMARY SEVERE RISKS WILL BE WITH THE MORNING PRE-FRONTAL CONVECTION FROM KS/OK INTO MO/IA...AND WITH ADDITIONAL WARM SECTOR SUPERCELL DEVELOPMENT FROM SE OK/NE TX INTO AR. ...ARKLATEX NEWD ACROSS MUCH OF AR/SRN MO... THE RICHEST MOISTURE IN THE WARM SECTOR IS SPREADING INTO SRN AR AND NE TX BENEATH STEEP MIDLEVEL LAPSE RATES PER 12Z SOUNDINGS. STRONG SURFACE HEATING EXPECTED ACROSS NRN LA AND SRN AR THROUGH THE AFTERNOON...WHERE UPPER 60S BOUNDARY LAYER DEWPOINTS AND AFTERNOON TEMPERATURES NEAR 80 F WILL SUPPORT MLCAPE OF 2500-3000 J/KG. THE N/NE EDGE OF THE STRONGER BUOYANCY /SW OF THE ONGOING WAA STORMS OVER E AND NE AR THIS MORNING/ WILL COINCIDE WITH STRONG LOW-LEVEL SHEAR AND A 40-50 KT LLJ. IT APPEARS THAT THE EARLY PRE-FRONTAL CONVECTION IN NE TX/ERN OK WILL EVENTUALLY EVOLVE INTO WARM SECTOR SUPERCELLS THIS AFTERNOON...AS DESTABILIZATION PROCEEDS AND AS VERTICAL SHEAR PROFILES IMPROVE WITH PASSAGE OF THE LEAD SHORTWAVE TROUGH THIS MORNING. A FEW STRONG/LONG-TRACK TORNADOES WILL BE POSSIBLE WITH THESE SUPERCELLS...GIVEN EFFECTIVE SRH OF 300-400 M2/S2...MODERATE BUOYANCY...AND MOIST LOW LEVELS. A DISCRETE OR CLUSTER SUPERCELL MODE WILL LIKELY CONTINUE FROM THIS AFTERNOON THROUGH TONIGHT ACROSS AR...PROLONGING THE TORNADO AND SEVERE THUNDERSTORM RISK. ...CENTRAL NEB TO SRN IA/ERN KS/MO THROUGH THIS EVENING... THE FORECAST SITUATION HAS BEEN COMPLICATED SUBSTANTIALLY BY AN EXPANSIVE BAND OF MORNING CONVECTION ALONG AND AHEAD OF THE PACIFIC COLD FRONT/DRYLINE FROM ERN OK NWD ACROSS ERN KS TO SE NEB. THIS CONVECTION HAS PROPAGATED WELL E OF THE SURFACE COLD FRONT/DRYLINE AND IS ASSOCIATED WITH ASCENT ABOVE THE SURFACE PRECEDING THE INITIAL SPEED MAX ROTATING AROUND THE DEVELOPING MIDLEVEL LOW NEAR THE KS/CO BORDER. THE PRIMARY SEVERE THREAT FROM ERN KS INTO MO/IA WILL BE WITH A CONTINUATION OF THIS ONGOING CONVECTION. SOME DESTABILIZATION WILL OCCUR IN ADVANCE OF THIS CONVECTION...THOUGH WIDESPREAD CLOUDS WILL HINDER SURFACE HEATING SOME. ALSO...THE CONVECTIVE MODE IS ALREADY MESSY/COMPLEX AND MAY REMAIN SO THROUGH THE AFTERNOON GIVEN THE PRONOUNCED BACKING OF MID-UPPER FLOW NOTED IN KS/MO VWP/S. A MIX OF EMBEDDED BOWS AND SUPERCELLS WILL BE CAPABLE OF PRODUCING LARGE HAIL AND DAMAGING GUSTS...AS WELL AS A FEW TORNADOES. BOUNDARY LAYER DEWPOINTS REMAIN IN THE 58-60 F RANGE NEAR AND BEHIND THIS INITIAL CONVECTION...SUCH THAT ADDITIONAL STORM DEVELOPMENT WILL BE POSSIBLE ALONG THE SURFACE BOUNDARY AND WITHIN THE MIDLEVEL DRY SLOT THIS AFTERNOON ACROSS CENTRAL NEB AS SOME CLEARING OCCURS FROM THE S. SUPERCELLS WILL BE POSSIBLE IN THIS EXPECTED ARC OF CONVECTION...WITH A COUPLE OF TORNADOES...LARGE HAIL...AND A FEW DAMAGING GUSTS POSSIBLE THIS AFTERNOON. 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