ZCZC SPCSWOMCD ALL ACUS11 KWNS 091956 SPC MCD 091956 MNZ000-NDZ000-092200- Mesoscale Discussion 1452 NWS Storm Prediction Center Norman OK 0256 PM CDT Mon Aug 09 2021 Areas affected...Portions of central and eastern North Dakota. Concerning...Severe potential...Watch likely Valid 091956Z - 092200Z Probability of Watch Issuance...80 percent SUMMARY...Severe thunderstorm development is expected within the next 1 to 2 hours. Large hail, damaging winds, and perhaps a tornado are all possible. DISCUSSION...19Z surface analysis shows a ~1006mb surface low near Sheridan, North Dakota. Extending east front this surface low is a stationary front which extends into northwest Minnesota. This boundary has been reinforced by precipitation for much of the morning, but now that convection is waning, may begin to lift north as a warm front through the afternoon and evening. In addition, a cold front extends from near this surface low southward to central South Dakota. Deep-layer ascent has started to spread eastward ahead of an approaching upper-level low with expanding cloud cover and some elevated convection across northwest North Dakota. In the last 30 minutes, some low-level cumulus has started to develop near the low-pressure center and extending southward along the cold front. Vertical development currently appears limited, and SPC mesoanalysis still shows inhibition across the region. However, expect this inhibition to erode over the next 1 to 2 hours as stronger ascent arrives. The environment is favorable for supercells given around 1500 J/kg MLCAPE (forecast to increase above 2000 J/kg) and effective shear around 40 to 50 knots per SPC mesoanalysis. Large hail will likely be the primary threat given the storm mode, steep mid-level lapse rates, and storm motion which will likely cause storms to move to the cool side of the stationary front and perhaps become elevated. However, there will also be a threat for severe wind and perhaps a tornado or two. The best tornado potential would likely be along or maybe slightly on the northern side of the stationary front where enough warming has occurred for surface based storm development in a region with significantly backed surface winds. Weak winds (<20 knots) in the lowest 2km per regional RAOBs will also be a limiting factor to a greater tornado threat. A watch is likely within the hour. ..Bentley/Thompson.. 08/09/2021 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...FGF...BIS... LAT...LON 48110124 49020053 49089718 48499716 47079698 46599706 46319920 46650051 48110124 NNNN