MD 1999 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF THE BLACK HILLS IN SOUTHWESTERN SOUTH DAKOTA INTO FAR NORTHERN NEBRASKA Mesoscale Discussion 1999 NWS Storm Prediction Center Norman OK 0203 PM CDT Sun Aug 16 2026 Areas affected...portions of the Black Hills in southwestern South Dakota into far northern Nebraska Concerning...Severe potential...Watch unlikely Valid 161903Z - 162100Z Probability of Watch Issuance...20 percent SUMMARY...Isolated thunderstorms are forecast to evolve southeastward out of the Black Hills through this evening. The primary hazards will be isolated large hail and damaging wind gusts. DISCUSSION...Convective development is ongoing across portions the Black Hills in southwestern South Dakota and adjacent areas of Montana/Wyoming. Expectation is for at least an isolated thunderstorm or two to eventually evolve southeastward out of the Black Hills. While available buoyancy remains weak as of 1900 UTC, further insolation should result in additional destabilization through the afternoon to around 1000-1500 J/kg MLCAPE. Effective shear of 30-40 kts and steepening mid-level lapse rates may promote a supercell or two capable of isolated large hail, with steep low-level lapse rates and the possibility of eventual clustering also supporting a risk for occasional damaging/severe wind gusts. Current expectations are for thunderstorm/severe coverage to remain too isolated for watch issuance; however, a targeted Severe Thunderstorm Watch could be considered should convective coverage/severe risk trend greater than anticipated. ..Chalmers/Guyer.. 08/16/2026 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LBF...UNR... LAT...LON 42840195 43010273 43410329 43900377 44210398 44500403 44680385 44650321 44340258 43720168 43490148 43210137 43050144 42890164 42840195 MOST PROBABLE PEAK WIND GUST...55-70 MPH MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN Read more

Full outlook from NOAA / Storm Prediction Center.

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