Severe Storm Outlook Narrative (AC)
Issued by NWS
Issued by NWS
680 ACUS48 KWNS 130908 SWOD48 SPC AC 130906 Day 4-8 Convective Outlook CORR 1 NWS Storm Prediction Center Norman OK 0406 AM CDT Thu Aug 13 2026 Valid 161200Z - 211200Z CORRECTED FOR TEXT ...DISCUSSION... ...D4/Sunday... Strong to potentially severe thunderstorms are expected to develop in association with a cold front that will move across parts of the Midwest, Ohio Valley, and northern Mid-Atlantic on Sunday. Deep-layer shear is generally forecast to remain weak, but moderate unidirectional westerly flow (potentially 30-40 kt in the 850-500 mb layer) within a favorably moist and unstable environment will support potential for multiple storm clusters with wind-damage potential. Uncertainty remains regarding frontal timing and the influence (if any) of MCVs emanating from the Plains and Midwest. Also, given the generally weak deep-layer shear, the magnitude of the severe threat will be strongly influenced by the extent of pre-convective heating and steepening of low-level lapse rates. Confidence is too low to add a 15% area at this time, though severe probabilities will likely be needed later in the outlook cycle. ...D5/Monday... The front will move southeastward on Monday into parts of the mid-MS/lower Ohio Valleys and Mid-Atlantic/Carolinas. Scattered storms are again expected along/ahead of the front. Some weakening of low/midlevel flow is expected and deep-layer shear will remain modest at best, so the severe threat may remain rather isolated. Farther west, increasing moisture and instability within a modest west-northwesterly flow regime could result in some severe-storm potential from the central High Plains into the Dakotas. ...D6/Tuesday - D8/Thursday... Predictability regarding the upper-level pattern begins to wane by early/mid next week. In general, periodic bouts of severe storms may continue across parts of the central/northern Plains and Upper Midwest, along the periphery of a persistent upper ridge. A less-organized severe threat may also persist near the remnant frontal zone across parts of the Southeast/Carolinas. ..Dean.. 08/13/2026