SPC MD 684

MD 0684 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF THE CENTRAL HIGH PLAINS Mesoscale Discussion 0684 NWS Storm Prediction Center Norman OK 0110 PM CDT Sat May 09 2026 Areas affected...portions of the central High Plains Concerning...Severe potential...Watch unlikely Valid 091810Z - 092045Z Probability of Watch Issuance...20 percent SUMMARY...High-based thunderstorms will bring a risk for isolated severe wind gusts and small to perhaps marginally severe hail this afternoon from southeastern Wyoming into the Nebraska Panhandle and northeastern Colorado. DISCUSSION...Latest GOES water vapor imagery depicts a mid-level shortwave trough embedded within broad northwesterly flow moving southeastward from southern Montana into northwestern Wyoming. While low-level moisture remains very limited (dewpoints in the 30s F), cooling temperatures aloft downstream of this shortwave and continued insolation are yielding steepening low- and mid-level lapse rates per latest mesoanalysis. Model forecast soundings suggest that this will be sufficient for the development of weak buoyancy (250-500+ J/kg MLCAPE) by early-to-mid afternoon. Expectation is for ongoing, high-based convection across northern Wyoming to progress southeastward, with additional development likely across the high terrain areas of central/southeastern Wyoming over the next couple of hours. Despite the aforementioned limited low-level moisture, steep low-level lapse rates and dry, well-mixed boundary layer profiles will support the potential for isolated severe wind gusts. 30-40 kts of effective bulk shear and steep mid-level lapse rates may also promote some risk for small to perhaps marginally severe hail with any stronger updrafts. With time, convection will spread southeastward into the Nebraska Panhandle and northeastern Colorado, with some potential for upscale growth into linear segments should cold pools coalesce. Given the forecast limited coverage/magnitude of the severe threat, watch issuance is unlikely at this time. ..Chalmers/Gleason.. 05/09/2026 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BOU...CYS...RIW... LAT...LON 41680678 42020741 42170765 42450766 42810725 43020649 43130584 43030532 42640451 41910321 41510269 40970269 40450309 40310397 40880518 41680678 MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN Read more