Severe Storm Outlook Narrative (AC)
Issued by NWS
Issued by NWS
912 ACUS02 KWNS 180507 SWODY2 SPC AC 180505 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1205 AM CDT Sat Jul 18 2026 Valid 191200Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTHERN PLAINS...AND PARTS OF NORTH CAROLINA INTO SOUTHEAST VIRGINIA... ...SUMMARY... Isolated to widely scattered strong to severe thunderstorms may pose a risk for damaging wind gusts across portions of the southern Appalachians to the coastal Carolinas/southeast Virginia vicinity on Sunday. Strong to severe storms may also develop across parts of eastern Montana into North Dakota and Minnesota. ...Southern Appalachians to the Coastal Carolinas/Southern VA... An upper trough over the eastern U.S. will persist on Sunday. At the surface, a cold front will develop southward across VA toward the NC/VA border. Near and south of this front, a very moist airmass will be in place (70s F dewpoints), and strong heating will foster a corridor of moderate instability. Deep-layer flow will remain modest, with effective shear values typically only around 20-25 kt. However, steep low-level lapse rates and PW values near/above 2 inches are present in forecast soundings. Storms that develop will pose a risk for wet microbursts, and a greater wind risk may evolve closer to the cold front where sufficient clustering occurs. ...Northern Plains into northern MN... A compact upper low/shortwave trough over Alberta will develop east/southeast on Sunday, emerging over the Canadian Prairies and northern Plains. As this occurs, a belt of strengthening west/northwesterly mid/upper flow will overspread the region. A surface cold front will develop southeast across eastern/southern MT during the afternoon, and the Dakotas during the evening/overnight hours. Southerly low-level flow ahead of this feature will transport modest moisture northward into the area. Steep midlevel lapse rates will support 1000-2000 J/kg MLCAPE amid 40+ kt effective shear magnitudes. Initial convection may be cellular, posing a risk for isolated large hail. Given steep low-level lapse rates, strong outflow winds also will be possible, and some potential for a bowing cluster of storms is possible if sufficient storm coverage occurs ahead of the cold front from southern/eastern MT into the Dakotas through evening. Overnight storms may persist eastward into northern MN, though severe potential is less certain across this area given stronger capping. ..Leitman.. 07/18/2026 $$