USA Weather — Severe Weather Division
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF NORTHWESTERN KANSAS...
...SUMMARY...
SEVERE THUNDERSTORMS ARE LIKELY THIS AFTERNOON INTO TONIGHT ACROSS THE CENTRAL AND SOUTHERN GREAT PLAINS. VERY LAGRE TO GIANT HAIL, A FEW STRONG TORNADOES, AND DAMAGING WINDS WILL ALL BE POSSIBLE.
...SOUTHERN/CENTRAL GREAT PLAINS...
A NEGATIVELY TILTED SHORTWAVE CURRENTLY LOCATED OVER THE SOUTHERN GREAT BASIN WILL EJECT NORTHEASTWARD INTO THE CENTRAL PLAINS THROUGH THE END OF THE PERIOD. AHEAD OF THE TROUGH, A BROAD AREA OF MODERATE TO STRONG SOUTHWESTERLY MID-LEVEL FLOW WILL OVERSPREAD A BROAD WARM/MOIST SECTOR, ALONG WITH INCREASING HEIGHT FALLS AND COOLING MID-LEVEL TEMPERATURES. LEE CYCLOGENESIS IS EXPECTED TO TAKE PLACE THIS MORNING AND BEYOND OVER THE CENTRAL HIGH PLAINS IN RESPONSE TO THESE HEIGHT FALLS. A DRYLINE EXTENDING SOUTHWARD THROUGH THE HIGH PLAINS SLOWLY MIXES EASTWARD. A BROAD WARM SECTOR AHEAD OF THIS DRYLINE IS ALREADY DEVELOPING WITH 60S DEWPOINTS EXTENDING INTO SOUTHWEST KANSAS. AS THE WARM FRONT RAPIDLY LIFTS NORTHWARD AND A SOUTHERLY LOW-LEVEL JET STRENGTHENS TODAY, MID 60S DEWPOINTS SHOULD EXTEND WELL NORTHWARD INTO FAR SOUTHERN NEBRASKA BY THIS EVENING, ALONG WITH MODERATE TO STRONG BUOYANCY AND INCREASING DEEP-LAYER SHEAR. ONGOING STORMS THIS MORNING ACROSS EASTERN KANSAS AND OKLAHOMA WILL PRODUCE WESTWARD-ADVANCING OUTFLOW, WHICH WILL LIMIT THE EASTWARD EXTENT OF THE WARM SECTOR.
FORCING FOR ASCENT AND SURFACE CONVERGENCE INCREASES THIS AFTERNOON WHICH SHOULD ALLOW FOR ISOLATED SUPERCELL DEVELOPMENT OFF OF THE DRYLINE BY MID TO LATE AFTERNOON, INITIALLY NEAR THE SURFACE LOW ACROSS WESTERN KANSAS. WITHIN THE WARM SECTOR, MODEL SOUNDINGS INDICATE STEEP LOW AND MID-LEVEL LAPSE RATES CONTRIBUTING TO 2500-300 J/KG MLCAPE CLOSER TO THE DRYLINE/SURFACE LOW. AN INITIAL THREAT FOR VERY LARGE TO GIANT HAIL IS EXPECTED THIS AFTERNOON WITH TORNADOES BECOMING AN INCREASING THREAT THIS EVENING AS THE LOW LEVEL JET STRENGTHENS. THE MAGNITUDE OF HELICITY WITH LARGE, CLOCKWISE-CURVING HODOGRAPHS MAY SUPPORT THE THREAT FOR A COUPLE OF STRONG TORNADOES, PARTICULARLY NEAR THE EFFECTIVE WARM FRONT CLOSER TO THE SURFACE LOW, WHERE SURFACE WINDS ARE MOST BACKED. MULTIPLE INTENSE SUPERCELLS APPEAR INCREASINGLY LIKELY ACROSS NORTHWESTERN KANSAS NEAR THE SURFACE LOW, WITH SOME AREAS RECEIVING MULTIPLE ROUNDS OF VERY LARGE TO GIANT HAIL. A MODERATE RISK DRIVEN BY HAIL HAS BEEN OUTLINED FOR THIS AREA.
FURTHER SOUTH LATER THIS EVENING, AN ADDITIONAL ROUND OF STRONG TO SEVERE STORMS APPEARS PROGGED TO DEVELOP AS THE UPPER TROUGH APPROACHES. THIS DEVELOPMENT SHOULD BE BIMODAL IN NATURE GIVEN LONGER HODOGRAPHS, WITH A MIX OF STORM CLUSTERS AND A FEW SUPERCELLS. STILL, A STRONG LOW-LEVEL JET SHOULD SUPPORT A THREAT FOR A FEW TORNADOES WITH A CONDITIONAL STRONG TORNADO THREAT IF AN INTENSE SURFACE-BASED SUPERCELL CAN DEVELOP. STORM CLUSTERS WILL ALSO POSE A THREAT FOR DAMAGING WINDS AND LARGE HAIL AS THEY PROPAGATE NORTHEASTWARD OVERNIGHT.
...CENTRAL/NORTHERN HIGH PLAINS...
SCATTERED HIGH-BASED STORMS SHOULD DEVELOP ACROSS THE CENTRAL TO NORTHERN HIGH PLAINS/BLACK HILLS REGION THIS AFTERNOON. LOW TO MID 50S DEWPOINTS WITH ROBUST SURFACE HEATING SHOULD SUPPORT DEVELOPMENT OF 1000-1500 J/KG WITH A DEEPLY MIXED BOUNDARY LAYER. MODERATE SHEAR SHOULD SUPPORT A MIX OF STORM CLUSTERS AND A FEW SUPERCELLS CAPABLE OF PRODUCING LARGE TO VERY LARGE HAIL AND DAMAGING WINDS. AN ISOLATED INTENSE WIND GUST CANNOT BE RULED OUT WITH THE MORE INTENSE HIGH-BASED STORMS GIVEN THE DEEP MIXING LAYER AND HIGH DCAPE.