Day 4-8 Outlook
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0358 AM CDT Thu Jul 24 2025
Valid 271200Z - 011200Z
...DISCUSSION...
Models indicate substantive amplification within an initially zonal
belt of westerlies across the northern mid-latitude Pacific during
the coming days, with several embedded closed lows evolving,
including one by the beginning of the period across the northeastern
Pacific, on the leading edge of an increasingly blocked regime.
Downstream, as another significant low, emerging from the Arctic
latitudes, turns across the eastern Northwest Territories into and
through Hudson Bay, mid/upper ridging is forecast to build through
much of the Canadian Prairies. Gradually, models indicate that
amplified ridging will encompass much of interior North America,
across and east of the Rockies through the mid to latter portions of
next week, while amplified troughing evolves further downstream,
across the eastern Canadian provinces, the Great Lakes and
Northeast.
The evolution of this regime appears likely to be accompanied by a
plume of steepening mid-level lapse rates overspreading the northern
U.S. Great Plains and adjacent portions of southern Canada, toward
the Upper Midwest/Great Lakes, during the early to middle portion of
next week, before becoming suppressed southwestward. Aided by the
return of seasonably high boundary layer moisture content to areas
near and northeast of the lower through middle Missouri Valley, it
appears that this will contribute to a broad area of moderate to
large potential instability.
This environment may become conditionally supportive of the
evolution of longer-lived organized thunderstorm clusters, with
potential to produce swaths of damaging wind gusts across parts of
the northern Great Plains, Upper Midwest and Great Lakes into the
Ohio Valley and perhaps parts of the Northeast. However, prior to
more substantive mid/upper trough amplification, and the southward
advancement of a cold front into much of the northeastern U.S. by
the middle of next week, the evolution of any such cluster, south of
the international border, will likely largely depend on subtle short
wave perturbations progressing through the larger scale ridging.
Given the low predictability of these features at this extended
range, and the uncertain impacts of their associated convection and
outflow on subsequent destabilization, severe probabilities remain
low due to the uncertainties.
Read more
