666
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