922 
ACUS48 KWNS 130755
SWOD48
SPC AC 130753

Day 4-8 Convective Outlook  
NWS Storm Prediction Center Norman OK
0253 AM CDT Sat Jun 13 2026

Valid 161200Z - 211200Z

...DISCUSSION...
...Days 5-6/Wed-Thu -- Lower MO/Mid-MS Valley to Ohio Valley and Mid-Atlantic...


An upper trough is forecast to deepen over the Upper Midwest/Great Lakes on Wednesday. As this occurs, an intensifying 500 mb jet streak will develop across the central Plains and increase to 80-100 kt as it moves into the Mid-MS Valley Wednesday night, and spreads eastward across the Ohio Valley and Northeast on Thursday.  

At the surface, low pressure will develop over the northern/central Plains late Tuesday night into early Wednesday. As this occurs, increasing southerly low-level flow will quickly transport rich Gulf moisture northward into the Lower MO/Mid-MS Valley by Wednesday afternoon as the surface low moves across IA and a trailing cold front moves eastward in tandem with the low across portions of the central Plains and Mid-MS Valley. Strong to extreme instability is forecast across the strongly sheared warm sector. An all-hazards severe thunderstorm event appears likely. An intense southwesterly low-level jet is expected to develop during the evening. This could support upscale growth into an MCS moving across portions of the Midwest Wednesday night, posing a risk for swaths of damaging winds. 

This system will spread east on Thursday across parts of the Ohio Valley into the Mid-Atlantic/Northeast. A continued risk for all severe hazards, and possible MCS with damaging winds, will persist as the mid/upper jet streak is forecast to remain quite strong as it overspreads a seasonally moist airmass. 

While some timing differences of aforementioned features is evident in various NWP guidance, overall medium range consensus and mean calibrated ML/AI guidance suggests a multi-day severe episode is likely as this system overspreads portions of the Midwest to the Mid-Atlantic/Northeast, though the 15 percent risk areas may shift in the coming days as details become better resolved, and higher probabilities are possible in subsequent outlooks. The southern extent of severe potential is more uncertain across parts of the Plains toward the TN Valley as these areas will remain further removed from stronger flow aloft. 

..Leitman.. 06/13/2026