Day 4-8 Convective Outlook
Issued: · Valid: –
Summary
Severe storms with the potential for damaging winds are expected to impact the Upper Midwest, Great Lakes, Ohio Valley, Northeast, and Mid-Atlantic from Monday through Wednesday.
Product Text
000 ACUS48 KWNS 170756 SWOD48 SPC AC 170755 Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0255 AM CDT Fri Jul 17 2026 Valid 201200Z - 251200Z ...DISCUSSION... ...Days 4-6/Mon-Wed -- Great Lakes/Midwest to the Mid-Atlantic/Northeast... A shortwave upper trough initially over the Canadian Prairies and northern Plains will develop east/southeast across the Upper Midwest/Great Lakes on Monday, then the Ohio Valley and Mid-Atlantic vicinity on Tuesday. Meanwhile, another upper shortwave trough will develop across the Great Lakes to the Northeast/Mid-Atlantic on Wednesday. These features will support enhancement of mid/upper level flow as a surface low tracks across Ontario/Quebec and New England during this time. A trailing cold front will likewise progress east/southeast over this three day period, with a very moist and unstable airmass present ahead of the front. This overall pattern will likely bring multiple days of severe storm potential from the Upper Midwest/Great Lakes to portions of the Ohio Valley, Northeast and Mid-Atlantic vicinity Monday through Wednesday, necessitating severe probabilities. While these areas may shift some over the coming day as the timing of mesoscale features and influence of prior days convection becomes more clear, these general regions are most likely to see at least isolated to widely scattered damaging wind potential as the upper trough and surface cold front sweep across the area. ...Days 7-8/Thu-Fri... Surface high pressure building behind the aforementioned surface cold front will become centered over the Midwest late in the forecast period. Upper troughing will persist across the East while an amplified upper ridge remains oriented from TX to MT. Overall, severe potential appears low late in the forecast period. ..Leitman.. 07/17/2026