ACUS48 KWNS 090902
SWOD48
SPC AC 090900

Day 4-8 Convective Outlook  
NWS Storm Prediction Center Norman OK
0400 AM CDT Thu Jul 09 2026

Valid 121200Z - 171200Z

...DISCUSSION...
Medium-range models continue to indicate that the center of strong
mid-level ridging building northeast of the Four Corners states will
shift across the middle Missouri Valley early next week, where it
may reach peak intensity by about Tuesday, before becoming
suppressed.  Even as this commences, mid-level ridging in the
westerlies may be maintained near and north/northeast of the
international border, from the Great Plains through the Great Lakes,
while large-scale downstream troughing amplifies southeastward
across the Northeast.

Associated with this evolution, a plume of very warm elevated
mixed-layer air still appears likely to advect on the southern
fringe of a belt of strengthening flow around the northern through
northeastern periphery of this ridging.  As the nose of the warmer
air overspreads the Great Lakes region early next week, forcing for
ascent associated with warm advection could begin supporting
organizing thunderstorm clusters potentially impacting portions of
New England, and/or the lower Great Lakes through Mid Atlantic.

As guidance suggests that the westerlies will initially remain split
downstream of the ridge, and a potentially notable short wave trough
(and associated cold front) migrating around its periphery and
eventually suppressing it, it remains unclear how potential frontal
and pre-frontal convection will pan out on any particular day.  Due
to both synoptic and sub-synoptic predictability issues, severe
probabilities remain at less than 15 percent in the day 6-8 time
frame.  However, this probably will change in later outlooks closer
to this time period, when the potential for introducing unduly large
forecast false alarm decreases.

..Kerr.. 07/09/2026