882 ACUS11 KWNS 282344 SWOMCD SPC MCD 282343 NDZ000-SDZ000-290145- Mesoscale Discussion 1369 NWS Storm Prediction Center Norman OK 0643 PM CDT Sun Jun 28 2026 Areas affected...parts of northwestern North Dakota Concerning...Severe potential...Watch unlikely Valid 282343Z - 290145Z Probability of Watch Issuance...20 percent SUMMARY...Isolated to widely scattered strong thunderstorm development with potential to produce large hail and localized strong downbursts is possible into the 7-9 PM CDT time frame, before rapidly weakening. DISCUSSION...In the wake of one notable mid-level short wave trough, pivoting north-northwestward across Saskatchewan/Manitoba, around the northeastern periphery of an occluded cyclone centered over far southeastern Alberta, mid/upper support for convective development across the region is weak. Low-level flow is also weak within broad weak lingering surface troughing centered over the western Dakotas, but convergence has become strong enough in locations to contribute to the initiation of isolated thunderstorms. Boundary-layer destabilization has maximized, and mid-level inhibition associated with a plume of warm elevated mixed-layer air has been suppressed southeastward. Despite the weak low-level flow and shear, deep-layer shear beneath 40-50 kt southwesterly 500 mb flow is strong and supportive of supercells with potential to produce large hail, as likely was the case with one initial storm which evolved across the international border to the east-northeast of Williston earlier. It is possible ongoing convection may persist and intensify further the next couple of hours, particularly the cell developing to the south-southwest of Bismarck, which appears likely to have the most prolonged access to updraft inflow of moist air characterized by CAPE on the order of 3000 J/kg. However, with the onset diurnal cooling and increasing inhibition for boundary-layer parcels, weakening and dissipation of storms may be rapid. ..Kerr/Thompson.. 06/28/2026 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...FGF...ABR...BIS... LAT...LON 48920251 49060203 48849924 48479885 47669903 46460049 45900148 46320191 47210140 47470187 48250278 48920251 MOST PROBABLE PEAK WIND GUST...55-70 MPH MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN