490
ACUS48 KWNS 090841
SWOD48
SPC AC 090838

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0338 AM CDT Tue Jun 09 2026

Valid 121200Z - 171200Z

...DISCUSSION...
...Day 4/Friday...

The last several deterministic model runs have consistently shown
the progression of a short-wave trough and associated 50 kt jet
streak from the OH Valley into the St. Lawrence Valley, with
meaningful height falls as far south as the Mid-Atlantic. At the
surface, the northern portion of a cold front initially from
southwest Ontario to near the confluence of the MS and OH Rivers and
into the southern Plains will progress southeast and eventually
merge with a trough stretching from southern New England to the
Carolina Piedmont. Ahead of the front, boundary-layer dewpoints in
the 60s to low/mid 70s will combine with modestly steep mid-level
lapse rates, especially across the lower Great lakes, to yield a
moderately unstable air mass by afternoon.

Initial storms are anticipated across the lower Great Lakes into
upper OH Valley by early afternoon, with activity advancing east
toward the Hudson Valley, and southeast into the central
Appalachians and Mid-Atlantic through the remainder of the afternoon
into evening. The strongest vertical shear is forecast from the
lower OH Valley to the lee of the lower Great Lakes, where organized
storm modes capable of damaging winds and large hail appear most
probable.

Elsewhere, a more isolated severe-weather threat may materialize
within a low-level upslope regime in eastern NM.


...Day 5/Saturday...

The models are in generally good agreement in depicting a
mid/upper-level low over Ontario, and a positively tilted trough
from the northern Plains into the northern Rockies. A belt of
enhanced, westerly winds in the mid levels will reside to the south
of those features, from the northern and central Plains through the
Great Lakes. At the surface, the various ensemble members
consistently show the clustering of low centers over the central
High Plains with an associated surface front extending into the
upper Great Lakes.

Moderate to strong instability is forecast ahead of the surface
front from the central Plains into upper Great Lakes with more than
sufficient deep-layer to support higher-order storm modes. Highest
confidence in storm development Saturday afternoon and evening is
across the central Plains into mid/lower MO Valley from the vicinity
of the surface low northeast along the surface front.

Other more isolated severe storms appear possible along a weakening
front in the Carolinas.


...Day 6/Sunday...

The ensemble mean solutions depict lowering mid-level heights from
the central Plains into Great Lakes and OH Valley, in conjunction
with the gradual amplification of a long-wave trough located east of
the North American Rockies. More specifically, a number of the
deterministic models suggest a short-wave trough moving from the
northern into central Rockies, with another potentially more intense
mid-level system moving through the Northeast.  An associated
surface front preceding both features may serve as the focus for
some severe-weather threat from the Northeast through the OH Valley
into the Southern Plains. However, there is considerable uncertainty
in finer-scale details, so no area will be highlighted.


...Days 7-8/Monday and Tuesday...

Further amplification of the long-wave trough is forecast with an
associated belt of mid-level flow extending from the central Plains
through the mid MS Valley into New England and the Mid-Atlantic.
Despite growing spread across the deterministic models, there is a
modest signal that the Day 6/Sunday central Rockies short-wave
trough will progress through the central Plains into  mid MS Valley.
Some severe-weather threat could develop ahead of that disturbance
in the vicinity of the surface frontal system, should that scenario
unfold as advertised.

..Mead.. 06/09/2026