Day 4-8 Convective Outlook
Issued: · Valid: –
Summary
Severe storms capable of producing large hail and damaging winds are expected across northeast Iowa and near the central Plains on Tuesday afternoon and evening. Isolated severe weather may also occur across the Mid-South and Tennessee Valley through Wednesday and Thursday.
Product Text
000 ACUS48 KWNS 150754 SWOD48 SPC AC 150752 Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0252 AM CDT Sat Aug 15 2026 Valid 181200Z - 231200Z ...DISCUSSION... ...Day 4/Tue - NE/IA and vicinity... An upper trough over the Great Lakes/Midwest will deepen on Tuesday, with increasing northwesterly flow aloft overspreading portions of the northern/central Plains to the Mid/Upper MS Valley. Rich boundary layer moisture will be in place ahead of a south/southeastward-developing surface front. There is some uncertainty regarding possible early-day convection of cloud debris across parts of the region. However, most guidance suggests a corridor of strong instability will develop by afternoon. Supercell wind profiles will support organized cells, possibly growing upscale with time along the surface front. Initially, a large hail risk could transition toward more of a damaging wind risk, particularly if upscale growth does occur as storms develop southeast through the evening. ...Days 5-8... Upper trough will deepen across the eastern U.S. and persist into the weekend. Meanwhile, an amplified upper ridge will remain in place across the western U.S. A surface front will sag south and east on Wednesday and Thursday as upper trough deepens and surface high pressure builds over the Great Lakes. Some isolated severe risk could emerge over the Mid-South/TN valley toward the Eastern Seaboard in response, but deep-layer flow will remain weak and low-level winds mostly parallel to the surface front, limiting a more substantial/organized risk. ..Leitman.. 08/15/2026