Day 4-8 Convective Outlook

Issued: 2026-08-14 07:55 UTC  ·  Valid: 2026-08-17 12:00 – 2026-08-22 12:00 UTC

Summary

Severe thunderstorms capable of producing damaging wind gusts may develop ahead of a cold front in the Lower Ohio and Tennessee Valleys on Monday. Increased severe weather potential across parts of the Plains, Midwest, and Northeast is possible from Tuesday through Thursday.

Product Text

000 ACUS48 KWNS 140755 SWOD48 SPC AC 140754 Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0254 AM CDT Fri Aug 14 2026 Valid 171200Z - 221200Z ...DISCUSSION... ...Day 4/Mon... A cold front is forecast to extend from the Lower OH/TN Valleys toward the southern Mid-Atlantic Monday morning. Some severe risk could develop ahead of the boundary as it impinges on a seasonally moist and unstable airmass. However, vertical shear is expected to remain modest (20-30 kt 0-6 km shear). Thunderstorm clusters could pose a risk for locally damaging wind gusts, especially if sufficient clustering occurs given moderate to strong downstream instability. Severe probabilities may be needed in subsequent outlooks if a more organized severe risk appears more likely. ...Days 5-8/Tue-Fri... Low-amplitude westerly flow aloft will strengthen some around Day 5 or 6/Tue or Wed as a series of upper shortwave troughs move across the northern Plains to the Great Lakes and Northeast through Day 7/Thu. This could result in increase severe potential across portions of the Plains, Midwest, and perhaps the Northeast as the upper troughs pivot eastward. Given a prior cold frontal passage and surface high pressure across the Midwest through at least parts of Tuesday, it is uncertain how low-level moisture/thermodynamic recovery will evolve ahead of the upper feature. Depending on trends, severe probabilities may become necessary in later outlooks. ..Leitman.. 08/14/2026