Day 4-8 Convective Outlook

Issued: 2026-08-04 09:02 UTC  ·  Valid: 2026-08-07 12:00 – 2026-08-12 12:00 UTC

Summary

Potential for damaging winds may occur across the Great Lakes and Northeast regions from Saturday through the end of the period.

Product Text

000 ACUS48 KWNS 040902 SWOD48 SPC AC 040900 Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0400 AM CDT Tue Aug 04 2026 Valid 071200Z - 121200Z ...DISCUSSION... An upper high will remain over the southwestern states through much of the period, with a deep upper low gradually shifting eastward across Ontario Canada. In between, a zone of moderate northwest flow aloft will exist from the northern Plains/Upper MS Valley across the Great Lakes. At the surface, low pressure will exist over the central High Plains, with an east-west boundary roughly along I-80 from Nebraska eastward. Stronger cyclonic flow aloft will move out of the northern Plains on Fri/D4 and increase across the Great Lakes and into the Northeast from Sat/D5 through the end of the period, with midlevel winds around 30-40 kt possibly overspreading the surface front. A large area of upper 60s to lower 70s F dewpoints will remain along and south of the boundary, which may shift north/south as disturbances rotate around the Canadian upper low. Predictability remains low for denoting precise MCS corridors, but timing of the upper wave amplifications will be monitored in subsequent forecast cycles, with possible risk areas mainly for damaging wind potential. ..Jewell.. 08/04/2026