What you need to know

The NOAA Storm Prediction Center (SPC) has issued a Marginal Risk for severe thunderstorms today across portions of the Midwest and Ohio Valley, as well as Utah into far northwest Colorado. Isolated strong to severe storms are expected this afternoon and early evening, with locally damaging winds the primary concern. Yesterday's severe weather produced 53 wind reports and 13 hail reports, but no tornadoes.

Where is the highest risk today?

The Marginal Risk area covers two separate regions today. The primary zone stretches across parts of Indiana into Ohio and vicinity, where a mid-level vorticity maximum currently over Illinois and northwest Indiana will track eastward through the day. A secondary Marginal Risk area includes portions of Utah and far northwest Colorado on the periphery of an upper low centered over northern California.

The SPC's 0745 AM CDT outlook notes that "isolated strong to severe thunderstorms appear possible today across parts of the Midwest/Ohio Valley and Utah/far northwest Colorado."

When will storms develop?

Midwest and Ohio Valley: Thunderstorm development is expected this afternoon across Indiana into Ohio as the moist low-level airmass gradually destabilizes with daytime heating. Activity should continue through the early evening before weakening after sunset.

Later tonight—mainly after 10 PM CDT (03Z)—additional thunderstorms may develop over portions of Iowa and northern Illinois in a low-level warm advection regime. However, the SPC notes these storms "will remain elevated and well north of a stalled surface front," limiting severe potential.

Utah and Northwest Colorado: Ongoing thunderstorms this morning are occurring in a strongly sheared but weakly unstable environment. Renewed development is expected later this afternoon as filtered diurnal heating allows the moist low-level airmass to destabilize further.

What are the main threats?

Damaging winds are the primary hazard across the Midwest and Ohio Valley today. According to the SPC, "poor lapse rates aloft should tend to limit overall updraft strength, but locally damaging winds may occur with any loosely organized clusters that can form and spread eastward through the early evening."

In the Great Basin, isolated severe hail and wind gusts are possible with any cells or small clusters that develop this afternoon. The SPC notes that around 35-45 knots of southwesterly mid-level flow will persist across the region, providing sufficient shear for organized storms—though limited heating and instability will temper the overall severe risk.

Yesterday's severe weather recap

Tuesday brought widespread severe weather across the central United States, with 53 wind reports and 13 hail reports spanning Colorado, Illinois, Indiana, Kansas, Missouri, New Mexico, Oklahoma, Texas, and Utah. No tornadoes were reported.

Notable wind events included:

  • A 75 mph gust measured at McConnell Air Force Base in Kansas at 1942 UTC
  • Large panels ripped from a 70-foot wall at a Boeing/Spirit plant near McConnell AFB
  • Several railroad cars overturned near Avard, Oklahoma
  • An RV flipped along Highway 114 east of Smyer, Texas

The largest hail report was 2.00 inches (golf ball size) in Edgerton, Kansas at 2308 UTC. Multiple reports of quarter-size (1.00 inch) and half dollar-size (1.25 inch) hail were received from Kansas, Missouri, Illinois, and Texas.

Power outages and tree damage were widespread across western Missouri, with Richmond reporting multiple downed power poles, trees, and wires throughout the evening.

What about Thursday and beyond?

SPC Day 2 (Thursday, September 17) shows no severe weather risk categories at this time, with the outlook covering portions of Missouri, Ohio, the Midwest, Southeast, Northeast, Great Lakes, and Ohio Valley. Conditions are expected to remain relatively quiet as the mid-level vorticity maximum continues tracking eastward.

Looking ahead to Day 3 (Friday, September 18), a Marginal Risk returns to portions of Kansas, Nebraska, Missouri, Mississippi, Tennessee, Florida, Ohio, Iowa, and South Dakota. The Mississippi Valley and Tennessee Valley will be the primary focus areas as a new weather system approaches from the west.

Staying alert during Marginal Risk days

While Marginal Risk days represent the lowest category on the SPC's five-tier scale, they still warrant attention—especially for outdoor activities and travel. Isolated severe storms can produce localized damaging winds, large hail, and frequent lightning with little advance warning.

Third-party weather apps are silenced by Do Not Disturb, though Wireless Emergency Alerts for tornado warnings still break through on most phones. For severe thunderstorm warnings—which cover damaging wind and hail threats—most notification systems remain silent during sleep hours unless you've taken specific steps to enable alerts.

VORTEX is a free web app at vortexintel.app that monitors severe weather nationwide. Pro ($4.99/month) places phone calls to your phone when a tornado or flash flood warning is issued for a location you care about — calls can ring through Do Not Disturb once you enable Emergency Bypass for the number, unlike most third-party app notifications.