ZCZC SPCSWOMCD ALL ACUS11 KWNS 212040 COR SPC MCD 212040 COR WYZ000-MTZ000-IDZ000-UTZ000-NVZ000-212230- Mesoscale Discussion 1575 NWS Storm Prediction Center Norman OK 0340 PM CDT Sat Aug 21 2021 Areas affected...portions of the Intermoutnain West Concerning...Severe potential...Watch unlikely Valid 212040Z - 212230Z CORRECTED FOR TYPO Probability of Watch Issuance...20 percent SUMMARY...Scattered thunderstorm development ongoing across portions of NV, ID, UT and WY will continue through this evening with a risk for hail and damaging wind gusts with the strongest storms. DISCUSSION...As of 2030 UTC, Regional WV imagery showed a well-developed mid-level low across the northwestern US. Forecast to move east this afternoon and evening, ascent from the low will continue to slowly overspread much of the central Rockies and Great Basin where a cold front lies from southwestern Wyoming into northeastern Nevada. Radar and satellite trends show weak convection has emerged across the area with additional development likely over the next several hours. Driven by steep mid-level lapse rates beneath the cold pocket aloft, RAP soundings indicate around 500 J/kg of MLCAPE is present. A mid-level speed max of 40-50 kt around the base of the trough will support moderately strong shear profiles supportive of organized multicells and perhaps weak supercells. While buoyancy will be limited, low-level inverted v profiles will support strong downdrafts with the potential for damaging wind gusts. Cooling 500 mb temperatures (-12 to -14 C) will also support the risk of hail, especially with the stronger cells. Hi-res guidance and observational trends suggest the greatest risk for organized severe potential may be associated with storms currently developing near the cold front from eastern NV, into northern UT and western WY. Here, greater lift and buoyancy in proximity to the front may contribute to stronger convection and better potential for organization. Convective trends will be monitored, but uncertainty on the longevity of any organized severe threat suggests a watch is unlikely. ..Lyons/Guyer.. 08/21/2021 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...RIW...TFX...SLC...PIH...BOI...LKN... LAT...LON 40091347 39801430 39661559 40111589 41581476 43111341 43981261 44721193 44961132 44871075 44271011 43181001 42291030 41801065 41381114 40651231 40431276 40091347 NNNN