DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1109 AM CDT MON MAY 24 2010

VALID 241630Z - 251200Z

...THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON/EVENING FOR NW NEB...WRN SD...S CENTRAL ND...

...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK...ACROSS MUCH OF THE GREAT PLAINS...

...CENTRAL/NRN PLAINS THROUGH EARLY TONIGHT... A STRONG NEGATIVE TILT MIDLEVEL TROUGH WILL EJECT NNEWD FROM THE CENTRAL ROCKIES TO THE NRN HIGH PLAINS AS AN ASSOCIATED SURFACE CYCLONE DEVELOPS NWD FROM CO TO THE WRN DAKOTAS ALONG A PRE-EXISTING BAROCLINIC ZONE. IN ADVANCE OF THE CYCLONE...THE WARM FRONT WILL MOVE NWD FROM CENTRAL SD/MN THIS MORNING TO CENTRAL ND AND NW MN BY LATE AFTERNOON. S OF THE WARM FRONT...A BROAD WARM SECTOR EXISTS WITH BOUNDARY LAYER DEWPOINTS OF 65-70 F BENEATH STEEP MIDLEVEL LAPSE RATES FROM THE UPPER MS VALLEY TO THE CENTRAL/SRN PLAINS. DAYTIME HEATING WILL FURTHER INCREASE INSTABILITY AND WEAKEN CONVECTIVE INHIBITION...RESULTING IN A BROAD AREA OF MODERATE-STRONG INSTABILITY.

THE SITUATION IS COMPLICATED SOMEWHAT BY A LEAD SHORTWAVE TROUGH NOW MOVING NNEWD OVER WRN OK/WRN KS. SATELLITE IMAGERY SHOWS A LOOSE BAND OF LOW-MIDLEVEL CONVECTION PRECEDING THIS WAVE...AND A CONSENSUS OF MODEL FORECASTS SUGGESTS THAT PRE-FRONTAL CONVECTION WILL DEVELOP BY MIDDAY-EARLY AFTERNOON FROM OK NWD TO SD /ALREADY FORMING IN CENTRAL NEB/. THESE STORMS WILL BE CAPABLE OF PRODUCING LARGE HAIL AND DAMAGING WINDS...WITH A GREATER RISK FOR SUPERCELLS FARTHER N INTO ERN SD AND SE ND LATER THIS AFTERNOON WHERE DEEP-LAYER AND LOW-LEVEL SHEAR WILL BE STRONGER IN PROXIMITY TO THE WARM FRONT.

FARTHER W...INITIAL THUNDERSTORM DEVELOPMENT IS ALREADY OCCURRING ACROSS ERN CO...AND ADDITIONAL THUNDERSTORM DEVELOPMENT IS EXPECTED FROM NEAR THE SURFACE LOW SWD ALONG THE TRAILING SURFACE TROUGH/COLD FRONT BY EARLY-MID AFTERNOON. HODOGRAPH CURVATURE AND FLOW ORIENTATION WILL BE MORE FAVORABLE FOR DISCRETE SUPERCELLS WITH TORNADOES CLOSER TO THE SURFACE LOW AND WARM FRONT IN SD. CELL INTERACTIONS AND BACKED FLOW ALOFT SUGGEST THE POTENTIAL FOR UPSCALE GROWTH INTO LINE SEGMENTS ACROSS KS/NEB THIS EVENING...THOUGH DISCRETE SUPERCELLS WILL BE POSSIBLE FOR THE FIRST FEW HOURS AFTERNOON INITIATION. FARTHER S...MORE ISOLATED SEVERE STORMS WILL ALSO BE POSSIBLE INTO THE TX PANHANDLE...INCLUDING THE POSSIBILITY OF SUPERCELLS ON THE SRN FRINGE OF THE STRONGER VERTICAL SHEAR. THE SEVERE STORM THREAT IS EXPECTED TO DIMINISH EARLY TONIGHT AS THE SURFACE LOW OCCLUDES INVOF WRN ND AND FORCING FOR ASCENT WEAKENS WITHIN THE REMAINING STRONGLY SHEARED WARM SECTOR ACROSS THE ERN DAKOTAS/WRN MN.

...MS VALLEY REGION THIS AFTERNOON... A WEAK MIDLEVEL VORTICITY LOBE IS ROTATING SWWD OVER SRN IL/WRN KY/WRN TN AROUND THE WRN PERIPHERY OF THE CLOSED LOW OVER SC. THE PRESENCE OF THIS WAVE AND STRONG INSTABILITY UPSTREAM IN THE LOW LEVELS SUGGESTS THAT THE ISOLATED ONGOING STORM CLUSTERS FROM SRN IL TO WRN TN WILL LIKELY INCREASE IN COVERAGE/INTENSITY THIS AFTERNOON. VERTICAL SHEAR WILL REMAIN WEAK...BUT A STEEP LAPSE RATE ENVIRONMENT WILL SUPPORT A RISK FOR ISOLATED STRONG/DAMAGING DOWNBURSTS AND MARGINALLY SEVERE HAIL THIS AFTERNOON.

..THOMPSON/HURLBUT.. 05/24/2010

Return to Chase Report May 24, 2010 by William Hark