563
ACUS48 KWNS 180855
SWOD48
SPC AC 180854

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0354 AM CDT Fri Jul 18 2025

Valid 211200Z - 261200Z

...DISCUSSION...
Medium-range guidance suggests that mid/upper ridging may remain a
prominent influence across much of the central and southeastern U.S.
through this period.  Beneath its northern periphery, across parts
of the northern Great Plains into Upper Midwest and Great Lakes/Ohio
Valley, it appears that a seasonably moist boundary-layer may become
characterized by moderate to strong diurnal destabilization each
day.  However, forcing for ascent to support convective development
remains unclear, and might be largely dependent on sub-synoptic
features with low predictability, particularly at this extended
range.

Sizable spread exists among the output concerning synoptic features
within the westerlies, as well.  However, there appears some signal
that a short wave perturbation, emerging either from the Pacific
Northwest or northwestern Canadian provinces early next week, could
be accompanied by an eastward advecting plume of elevated
mixed-layer air, low-level moistening and strengthening
lower/mid-tropospheric wind fields across parts of the Upper
Midwest/Great Lakes toward the St. Lawrence Valley/Northeast late
next Wednesday into Friday.  It might not be out of the question
that this regime could become supportive of one or two sustained,
organized clusters of storms capable of producing swaths of damaging
winds and some hail.

..Kerr.. 07/18/2025