MESOSCALE DISCUSSION 1664 NWS STORM PREDICTION CENTER NORMAN OK 0744 PM CDT THU SEP 08 2016 AREAS AFFECTED...PARTS OF S CNTRL SOUTH DAKOTA AND ADJACENT N CNTRL NEBRASKA CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY VALID 090044Z - 090245Z PROBABILITY OF WATCH ISSUANCE...20 PERCENT SUMMARY...FURTHER STORM INTENSIFICATION...INCLUDING AN ISOLATED SUPERCELL OR TWO...APPEARS POSSIBLE ACROSS SOUTH CENTRAL SOUTH DAKOTA DURING THE NEXT COUPLE OF HOURS. HOWEVER...THIS MAY NOT PERSIST MUCH BEYOND 03-04Z AND...GIVEN A RELATIVELY LIMITED AREAL EXTENT...A WATCH IS NOT CURRENTLY ANTICIPATED. DISCUSSION...SOUTHEAST OF A SURFACE LOW WITHIN LEE SURFACE TROUGHING ACROSS THE NORTHERN HIGH PLAINS...LARGE-SCALE FORCING FOR ASCENT APPEARS TO BE AIDING A SOMEWHAT CONFINED AREA OF INTENSIFYING THUNDERSTORM DEVELOPMENT...WEST NORTHWEST OF WINNER SD AND VALENTINE NEB. THIS IS WHERE THE INTERSECTION OF AN AXIS OF STRONGER SURFACE HEATING WITH LOW-LEVEL MOISTURE RETURN IS CONTRIBUTING TO A FAIRLY LOCALIZED AREA OF MODERATE INSTABILITY CHARACTERIZED BY CAPE ON THE ORDER OF 1500 J/KG. IN THE PRESENCE OF STRONG VERTICAL SHEAR BENEATH 50 KT WESTERLY 500 MB FLOW...AND ALONG A 30 KT SOUTHERLY 850 MB JET...THERE STILL APPEARS A WINDOW OF OPPORTUNITY FOR FURTHER STORM INTENSIFICATION ACROSS SOUTH CENTRAL SOUTH DAKOTA THROUGH THE 01-03Z TIME FRAME. THIS MAY INCLUDE A SUSTAINED SUPERCELL OR TWO BEFORE BOUNDARY LAYER INSTABILITY...AND PERHAPS AN AREA OF ENHANCED MID-LEVEL FORCING...WEAKEN. GIVEN SIZABLE BOUNDARY LAYER TEMPERATURE/DEW POINT SPREADS...LARGE HAIL AND LOCALLY STRONG SURFACE GUSTS APPEAR THE PRIMARY SEVERE HAZARDS. ..KERR/GUYER.. 09/09/2016 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...FSD...ABR...UNR... LAT...LON 43889966 44349925 44099850 43059918 43000043 43889966Read more
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